| 4s component of influenza virion rna represented by a set of trnas. | the aminoacceptor capacity of the 4s fraction of influenza virion rna--strain a/texas 1/77a (h3n2)--was studied in a cell-free system containing individual 3h-amino acids and rat liver ph 5-enzyme preparation. the presence of at least 5 species of active trna was demonstrated. there were differences in the composition of the trna populations of influenza virus and of the chick embryo chorioallantoic membrane cells in which the virus had cultivated. these differences point to the selectivity of t ... | 1983 | 6857988 |
| activity of cyclosporin a in experimental influenza virus infection in mice. | oral administration of the immunosuppressive fungal metabolite cyclosporin a increased the mortality of balb/c mice infected intranasally with influenza a/hong kong/1/68 (h3n2) virus. cyclosporin a also increased the amount of virus that could be recovered from the lungs of infected mice and delayed the rate at which it was eliminated. treatment with cyclosporin a did not, however, prevent the appearance of haemagglutination inhibiting antibody in the sera of animals that had been infected with ... | 1983 | 6858792 |
| recycling of h1n1 influenza a virus in man--a haemagglutinin antibody study. | sera from people born between 1883 and 1930 and collected in 1977 were tested for the presence of hi antibodies to a/fm/1/47 (h1n1) virus and three recently (1977 and 1978) isolated influenza a-h1n1 viruses. the highest frequency of high-titred antibody to the four h1n1 viruses was detected in sera from people born in 1903-4, i.e. 42, 54, 38, and 22% had antibody against a/fm/1/47, a/hong kong/117/77, a/brazil/11/78, and a/fukushima/103/78 respectively. the birthdate groups 1896-1907 showed a hi ... | 1983 | 6863911 |
| [oligopeptide mapping of the proteins of animal influenza virus nucleoproteins]. | oligopeptide mapping showed the viruses h1n1 and h3n2 isolated from animals, unlike the majority of animal viruses with "animal" subtypes of the surface antigens, to have np proteins typical of human h1n1 and h3n2 viruses which confirms their origin from human viruses. | 1983 | 6868550 |
| [procedures for estimating transmission parameters from influenza epidemics: use of serological data]. | a maximum likelihood procedure is given for estimating household and community transmission parameters from observed influenza infection data. the mathematical model used does not require the specification of infection onset times and, therefore, can be used with serological data which detect asymptomatic infections. infection data was derived by serology and virus isolation from the tecumseh respiratory illness study and the seattle flu study for the years 1975-1979. influenza a (h1n1), a (h3n2 ... | 1983 | 6868556 |
| [production of antibodies to influenza virus a by human lymphoid cells in vitro]. | the data are presented on studying the production of antibodies to influenza a (h3n2) virus by lymphoid cells of the amygdaline tonsils and mediastinal lymph nodes in vitro during stimulation of these cells with influenza virus or lipopolysaccharide of typhoid bacteria. | 1983 | 6871460 |
| investigation on the monsoon outbreak of influenza a (h3n2) virus strain in pune, india, 1981. | | 1983 | 6874028 |
| hemagglutinin-specific antibody responses in immunoglobulin g, a, and m isotypes as measured by enzyme-linked immunosorbent assay after primary or secondary infection of humans with influenza a virus. | the isotype-specific antibody responses to purified hemagglutinin of adults undergoing either primary or secondary infection with an influenza a virus were characterized by using an enzyme-linked immunosorbent assay. twenty-eight military recruits undergoing primary infection with a/ussr/92/77 (h1n1)-like virus had serum antibody rises in the immunoglobulin m (igm) (86%), igg (100%), and iga (96%) isotypes. in contrast, 19 adult volunteers undergoing secondary infection with a/peking/2/79 (h3n2) ... | 1983 | 6874068 |
| the similar interaction of ferret alveolar macrophages with influenza virus strains of differing virulence at normal and pyrexial temperatures. | the possibility that ferret lung macrophages may be one factor operating in vivo to prevent infection of susceptible alveolar cells (as demonstrated by organ cultures) by both virulent and attenuated strains of influenza virus has been investigated. phagocytosis of four strains of influenza virus [a/pr/8/34 (h1n1) and clone 64d (attenuated for ferrets) and clones 64c and 7a (virulent for ferrets) of the recombinant virus a/pr/8/34-a/england/939/69 (h3n2)] by ferret alveolar macrophages in vitro ... | 1983 | 6875518 |
| [isolation of spontaneous mutants from influenza a virus recombinants after several plaque passages in embryonic chicken cells]. | clones with larger plaques (2.5-4 mm in diameter) could be isolated after sequential passages of influenza virus recombinants a/greifswald 6/74 x a/pr8/34 (h3n1) and a/bangkok 1/79 x a/pr8/34 (h3n1 and h3n2) in chick embryo cells. in addition to the large plaques, very small ones (1-1.5 mm in diameter) could be regularly observed in a proportion of about 10% at subsequent passages of these variants. the clones exhibited a constant size of the plaques, and there were no large-plaque forming rever ... | 1983 | 6880027 |
| [production and properties of inhibitor-resistant mutants of influenza a virus recombinants]. | inhibitor-resistant (ir) mutants could be selected from recombinants between influenza virus a/pr8/34 (h1n1) and a/greifswald 6/74, a/greifswald, 1/76, a/erfurt 8/77 (all (h3n2)). spontaneous mutants were selected by cultivation on chorioallantoic membrane fragments in roller tubes, in the presence of 10% inactivated rabbit serum. the ir-mutants thus obtained were cloned during two successive plaque-to-plaque passages. the appearance of resistance to heat-stable rabbit serum inhibitors was conco ... | 1983 | 6880028 |
| [comparative study of the effectiveness of inactivated influenza vaccine preparations]. | the reactogenicity, safety, immunogenicity and epidemiological effectiveness of inactivated virion vaccinal preparations from strains a (h3n2) texas 1/77a, a (h1n1) and split adsorbed influenza chemical vaccine, as well as the character of local and systemic reactions to these vaccines were studied. the vaccinees showed a high percentage of seroconversions (42-69.4%) with antibody titers increasing 5 times and more. at the period of the epidemic outbreak of influenza in january 1980, caused by i ... | 1983 | 6880484 |
| different virulence of influenza a virus strains and susceptibility to pneumococcal otitis media in chinchillas. | we have previously shown that chinchillas infected with a multiply passaged laboratory strain of influenza a/nws/33 (h1n1) develop negative middle-ear pressure; polymorphonuclear leukocyte oxidative, bactericidal, and chemotactic dysfunction; and increased susceptibility to pneumococcal otitis media. because influenza a virus strains show different virulence in humans, three such strains were compared in the chinchilla model. negative middle-ear pressure and tympanic membrane inflammation develo ... | 1983 | 6885170 |
| ts p1 and p3 genes are responsible for satisfactory level of attenuation of ts-1a2 recombinants bearing h1n1 or h3n2 surface antigens of influenza a virus. | | 1980 | 6893373 |
| [subtypes h1n1 and h3n2 of influenza virus isolated from the same patient]. | | 1980 | 6927787 |
| a study of acute respiratory disease in the community of port chalmers. iii. efficacy of influenza virus subunit vaccines in 1973, 1974 and 1975. | an evaluation of the efficacy of influenza virus subunit vaccine was undertaken during a study of acute respiratory disease in the semi-isolated community of port chalmers, new zealand. in 1973, the administration of a vaccine containing a/england/42/72(h3n2) and b/roma/1/67 stains was found to produce hi antibody titres greater than or equal to 1:40 to the a and b components in 50 percent of 32 subjects. there was no significant ni antibody response to the a component. during an epidemic of a/p ... | 1980 | 6935541 |
| study of several genetic markers of two recombinants derived from autochthonous influenza virus type a strains. | two recombinants derived from autochthonous influenza virus type a strains were studied as regards neuraminidase activity, the rate of elution from chicken rbc and the sensitivity to nonspecific horse serum inhibitors. neuraminidase activity was lower in the a(h1n1) recombinant and in its collection and wild-type parents belonging to the same subtype than in the a(h3n2) recombinant and parental strains; the elution rate was much higher in the former than in the latter. in contrast to the parenta ... | 1982 | 6959412 |
| the replication of type a influenza viruses in the infant rat: a marker for virus attenuation. | twenty recombinant influenza virus strains bearing hsw1n1, h1n1 or h3n2 surface antigens, together with their respective wild-type or laboratory-propagated parent viruses, were inoculated into 2 day-old infant rats and their replication in the turbinates and lungs of these animals observed over a period of 5 days. in addition, the ability of each of the recombinant and parent viruses to enhance a subsequent infection of these infant rats by haemophilus influenzae type b was determined. the resul ... | 1980 | 6969291 |
| the human cytotoxic t cell response to influenza a vaccination. | the human cytotoxic t lymphocyte (ctl) response to challenge with influenza a vaccine was studied. six of eight volunteers given killed whole influenza virus a/ussr (h1n1) vaccine showed substantial increases on the level of ctl memory 1 month after immunization. the ctl measured at this time showed complete cross-reactivity in their specificity for influenza a/ussr (h1n1) and a/x31 (h3n2) infected cells and also showed hla restriction. the level of ctl memory increased in only three out of nine ... | 1981 | 6974066 |
| cord blood lymphocyte in vitro responses to influenza a antigens after an epidemic of influenza a/port chalmers/73 (h3n2). | samples of cord blood from 46 deliveries were collected between 2 and 8 mo after an epidemic of influenza caused by a/port chalmers/73 (h3h2) virus. of 10 samples with hai antibody titers against a/port chalmers of 1:16 or greater, one had 2-mercaptoethanol-sensitive igm class antibodies against the virus. lymphocyte proliferative responses with the use of a/port chalmers antigens were increased in six of 46 samples. these results provide immunologic evidence that certain neonates have igm antib ... | 1981 | 6974500 |
| specific anti-influenza virus antibody production in vitro by human peripheral blood mononuclear cells. | cultures of human peripheral blood mononuclear cells stimulated in vitro with influenza virus were found to produce anti-influenza virus antibody. an enzyme-linked immunosorbent assay was used to measure cumulative antibody secretion into culture supernatants. optimal antibody production was obtained with 2 x 10(6) peripheral blood mononuclear cells cultured in flat-bottomed wells for 12 days in 2 ml of rpmi 1640 medium supplemented with 10% fetal calf serum, antibiotics, and 4 mm l-glutamine. a ... | 1981 | 6975330 |
| evaluation of live and inactivated influenza a virus vaccines in a mouse model. | induction of cross-protective immunity against serologically distinct subtypes of influenza a virus in mice was examined in an attempt to correlate cross-protection with heterotypic lymphocyte responses. live and inactivated virus vaccines protected against the homologous subtype, but only whole virus protected against heterologous subtypes. live virus vaccines provided better cross-protection than inactivated virus vaccines. a weak defense against heterotypic challenge generated by live h0n1 vi ... | 1982 | 6977595 |
| the ecology of influenza viruses: a who memorandum. | influenza a viruses continue to be isolated from man, pigs, horses, and a wide range of avian species, especially ducks. the recent isolation of an influenza a virus from seals has added an additional mammal to the list of natural hosts for these viruses. in contrast, influenza b viruses have been isolated only from man.the haemagglutinin of a virus isolated from gulls in the united states of america could not be identified with reference antisera and may constitute a new haemagglutinin subtype. ... | 1981 | 6978194 |
| epidemiological, clinical, and virological features of influenza outbreaks in pune, india, 1980. | during the course of continuous surveillance of influenza in 1980 in pune, india, which has a tropical monsoon climate, three outbreaks of acute respiratory infection (ari) were investigated in march (hot season), in july-september (rainy season), and in november (cold season); sporadic cases during the interepidemic months were also studied. the first outbreak was associated with influenza a virus (h3n2), the second with influenza a viruses (h3n2) and (h1n1) and influenza b virus, but fewer inf ... | 1982 | 6982785 |
| characterization of human serum strain-specific antihemagglutinin antibody to a/port chalmers/73 (h3n2) influenza virus by radioimmunoprecipitation assays. | we performed radioimmunoprecipitation assays in which iodinated preparations of a/port chalmers/73 (a/pc/73) hemagglutinin were used as the test antigens and high concentrations of unlabeled a/hong kong/68 viral protein were used to inhibit the binding of cross-reactive antibodies to quantitate strain-specific antibody responses in postvaccination sera. strain-specific antibodies comprised 8 to 48% (mean, 20%) of the total a/pc/73 antigen-binding capacity of the sera tested. competition radioimm ... | 1982 | 6985298 |
| sensitivity and specificity of enzyme immunoassay for serodiagnosis of influenza a virus infections. | antibodies to influenza virus in sera from 40 patients infected with influenza a/ussr/90/77h1n1-like virus were measured by an enzyme immunoassay (eia), and results were compared with those obtained by complement-fixation (cf) and hemagglutination-inhibition (hai) tests. the sensitivity of eia in detecting an increase in influenza antibody in sera from these 40 patients was intermediate (27 of 40) between the cf test (19 of 40) and the hai test (35 of 40) when an ether-treater influenza a/ussr/7 ... | 1980 | 6989932 |
| use of the enzyme-linked immunosorbent assay to detect serum antibody responses of volunteers who received attenuated influenza a virus vaccines. | sera from volunteers who received live influenza a wild-type or ts recombinant virus were tested by hemagglutination inhibition (hi) assay, neuraminidase inhibition (ni) assay, and the enzyme-linked immunosorbent assay (elisa) to determine which assay system was the most sensitive in detecting an immunological response to infection. the elisa was performed with inactivated whole virus antigen, and the optical density at each of five serial twofold dilutions of pre- and postimmunization sera was ... | 1980 | 7011972 |
| infection with influenza a/victoria virus in houston families, 1976. | in 1976, an epidemic caused by infections with an influenza virus antigenically similar to a/victoria/75 (h3n2) occurred in houston, texas. during this outbreak, 37 families (155 members) enrolled in the houston family study were under observation. the families lived throughout the metropolitan area (houston, texas), and were representative of low income groups. the overall frequency of infection in family members was 27.7%. the frequency of infection was the highest for infants under one year o ... | 1981 | 7016989 |
| the antigenicity of whole virus versus subunit trivalent influenza vaccines -- a field trial in the israel defence forces, 1978. | a single dose of a commercial trivalent influenza subunit vaccine (sv) and two whole virus vaccines (wvv) were compared in a randomized, placebo-controlled field trial of subjects under 23 years of age in the israel defence forces. sixty percent of sv recipients and 29% and 37% of wvv recipients showed no measurable response to the h1n1 subtype (a/ussr). when the prevaccination titer to h1n1 was less than 10, sv did not differ significantly from the placebo, and when greater than or equal to 10, ... | 1981 | 7029236 |
| antigenicity in hamsters of inactivated vaccines prepared from recombinant influenza viruses. | inactivated vaccines prepared form influenza virus strains obtained by the recombination of a/pr/8/34 (h1n1) or a/fm/1/47 (h1n1) viruses with a/victoria/3/75 (h3n2) virus, were tested for their antigenicity in hamsters. the parental origin of the genes of each cloned recombinant virus was determined by polyacrylamide gel electrophoresis, and vaccines prepared from each strain by concentration, purification on sucrose density gradients and inactivation with formalin. all the recombinant strains u ... | 1981 | 7031128 |
| a clearance test in mice using non-adapted viruses to determine the immunogenicity of influenza strains. | a test for the immunogenicity of influenza viruses is described, which is based upon the intranasal vaccinating dose required to induce inhibition of multiplication of unadapted influenza viruses in the lungs of mice. this test is more sensitive than an antigen extinction procedure, in which immunogenicity is measured according to the dose required to induce the formation of hemagglutination-inhibition antibody. the clearance test has been used to demonstrate that a) influenza a/northern territo ... | 1981 | 7036956 |
| cold-adapted recombinant influenza a virus vaccines in seronegative young children. | two live, attenuated, intranasally administered influenza virus vaccines were evaluated in 21 seronegative young children at vanderbilt children's hospital (nashville, tennessee). the vaccines were derivatives of a cold-adapted master strain, influenza a/ann arbor/6/60 virus, containing the hemagglutinin and neuraminidase of one of two contemporary strains, influenza a/hong kong/123/77 (h1n1) or a/alaska/6/77 (h3n2) virus. both vaccine strains replicated in seronegative young children without ev ... | 1982 | 7045254 |
| pneumonia and influenza deaths during epidemics: implications for prevention. | pneumonia and influenza (p&i) deaths among adults during epidemics of influenza a (h3n2) virus are reviewed and risks of such deaths according to age and presence of chronic disease are estimated from medical records of a large group practice. thirty-eight deaths occurred among 310 persons hospitalized with p&i. flu-like symptoms occurred in 30 patients (79%), 26 patients (68%) were older than 65 years, 36 patients (95%) had chronic disease, and approximately half were medically stable before th ... | 1982 | 7053739 |
| responses of elderly subjects to a new subunit influenza virus vaccine. | the serologic responses and the side effects resulting from the administration of a new subunit vaccine against influenza were compared with those of a currently available whole-virus vaccine in an elderly population. the subunit vaccine is prepared by cleavage of the hemagglutinin and neuraminidase surface antigens from the virus with a cationic detergent, cetyltrimethylammonium bromide. the resulting vaccine is more selectively reduced to these primary antigens than are the available subunit v ... | 1982 | 7054332 |
| possible waterborne transmission and maintenance of influenza viruses in domestic ducks. | two duck farms in hong kong were examined monthly for 1 year for the occurrence and persistence of influenza viruses within the duck communities. the predominant virus in one community was h3n2, a virus antigenically related to the pandemic hong kong strain. this virus was isolated monthly throughout the year from feces or pond water or both, indicating a cycle of waterborne transmission. viruses of the same antigenic combination were isolated 1 and 2 years after the last sampling occasion, impl ... | 1982 | 7055370 |
| impact of influenza a in a nursing home. | outbreaks of influenza a in the institutionalized elderly have been reported only rarely. such an outbreak occurred in a nursing home in the period dec 12, 1980, through jan 21, 1981. thirty (25%) of the 120 residents had onset of influenza-like illness during the outbreak. influenza a/bangkok/79-like (h3n2) virus was isolated from throat swab specimens from five of eight acutely ill patients. thirteen persons were hospitalized; nine persons died (case-fatality ratio, 30%). this outbreak documen ... | 1982 | 7057536 |
| the binding of staphylococcal protein a by the sera of different animal species. | the capacity of purified immunoglobulin or serum to bind (125i)-labeled staphylococcal protein a (spa) was measured by means of an immunofiltration assay that facilitated the examination of large numbers of sera and required only a minute quantity of each. sera from 80 species, including humans, laboratory animals, domestic animals, and a variety of african mammals were examined. a wide interspecies variation in the spa-binding capacity of serum immunoglobulins was confirmed. only small variatio ... | 1982 | 7061862 |
| genetic composition and virulence of influenza virus: differences in facets of virulence in ferrets between two pairs of recombinants with rna segments of the same parental origin. | facets of virulence for ferrets of 16 recombinant clones of two parent viruses a/finland/4/74 (h3n2) and a/okuda/57 (h2n2) were determined and viewed in relation to their genetic composition. of the five pairs of recombinant clones with rna segments of the same parental origin, differences in facets of virulence were detected between members of two of the pairs. one pair differed in ability to produce fever, and another pair in ability to infect the lower respiratory tract. subsequent analyses i ... | 1982 | 7061993 |
| temperature-sensitive mutants of influenza a/udorn/72 (h3n2) virus. i. isolation of temperature-sensitive mutants some of which exhibit host-dependent temperature sensitivity. | | 1982 | 7064353 |
| temperature-sensitive mutants of influenza a/udorn/72 (h3n2) virus. ii. genetic analysis and demonstration of intrasegmental complementation. | | 1982 | 7064354 |
| studies on neuraminidase from influenza virus a(h3n2) obtained by two procedures. | 1. neuraminidase was obtained by (a) bromelain solubilization or (b) by treatment with n-lauroylsarcosine. 2. 5-n-acetyl-2-o-(3-methoxyphenyl)-alpha-d-neuraminic acid, employed as substrate, avoids the interference produced by the thiobarbituric acid method, and is not interfered by the ampholytes. 3. only about 20% of original enzyme activity was lost after electrofocusing. the sample from procedure a showed two peaks, corresponding to pis 4.4 and 5.6. the sample from procedure b, having a high ... | 1982 | 7067910 |
| elevation of nasal viral levels by suppression of fever in ferrets infected with influenza viruses of differing virulence. | the effect of suppression of fever on viral levels in nasal washes of ferrets infected with either of two clones (7a, virulent; 64d, attenuated) of the recombinant influenza virus a/puerto rico/8/34-a/england/939/69 (h3n2) was studied. the febrile response was reduced by shaving the ferrets or by treating them with sodium salicylate, which had no noticeable effect on the inflammatory response. for both clones, significantly more virus was shed in the nasal washes of ferrets whose febrile respons ... | 1982 | 7069233 |
| clinical reactions and serologic responses after vaccination with whole-virus or split-virus influenza vaccines in children aged 6 to 36 months. | the reactogenicity and immunogenicity of whole-virus and split-product influenza vaccines were studied in 77 children between the ages of 6 and 36 months. subjects initially received monovalent vaccine containing either a/ussr/77 (h1n1) antigen in 1978 or a/brazil/78 (h1n1) antigen in 1979. one month later a trivalent preparation was given which contained the respective h1n1 antigen plus a/texas/77 (h3n2) and b/hong kong/72 antigens. temperatures of greater than or equal to 37.8 c (greater than ... | 1982 | 7070886 |
| analysis of specific interactions influenza virus and cells of different sensitivity. note 2. characteristics of influenza virus-host cell interaction in persistent infection. | molecular hybridization was used for the demonstration of virus-specific rna synthesis in the latent phase of influenza virus replication in the sensitive mdck cell cultures and for its investigation in the persistent system represented by nonpermissive ao cells and influenza a/victoria 35/72 (h3n2). | 1982 | 7072150 |
| prevalence of hemagglutination inhibition antibody to current strains of the h3n2 and h1n1 subtypes of influenza a virus in sera collected from the elderly in 1976. | sera were collected in 1976 from 182 individuals born between 1876-1935, who included patients in a large local nursing home in orange county, california, and patients and staff at the university of california, irvine medical center. sera were treated with receptor-destroying enzyme and assayed for hemagglutination inhibition (hi) antibody to recent strains of influenza a virus. the antigens tested were: a/victoria/3/76 and a/texas/1/77 for subtype h3n2; a/new jersey/8/76, a/x53 and a/swine/1976 ... | 1982 | 7072705 |
| occurrence of temperature-sensitive influenza a viruses in nature. | the origin and characteristics of the first naturally occurring temperature-sensitive (ts) strain of influenza a virus identified in 1973, xia-ts, are described. natural ts strains were found to occur in the early egg passage material of all influenza a subtypes examined, but the proportion of ts virus varied from 8.3% for old h1n1 virus (1949 to 1957) to 82.4% for recent h3n2 virus (1979 to 1980). a number of strains were found to be composed of a mixture of ts and wild-type (ts+) particles. si ... | 1982 | 7077746 |
| sequence of the influenza a/udorn/72 (h3n2) virus neuraminidase gene as determined from cloned full-length dna. | | 1982 | 7080447 |
| estimating household and community transmission parameters for influenza. | a maximum likelihood procedure is given for estimating household and community transmission parameters from observed influenza infection data. the estimator for the household transmission probability is an improvement over the classical secondary attack rate calculations because it factors out community-acquired infections from true secondary infections. the mathematical model used does not require the specification of infection onset times and, therefore, can be used with serologic data which d ... | 1982 | 7081204 |
| [level of antibodies to influenza viruses a and b in the blood sera of children under 13]. | the level of antibodies to influenza a (h1n1), a (h2n2), a (h3n2), and b viruses in the blood sera collected in october and november, 1980, from 224 children under 13 resident in moscow and its suburbs was studied the results of the study showed convincingly the influenza a (h2n2) viruses did not circulate at that time among the population of moscow and its suburbs. the 4 positive (not exceeding 1 : 40 findings in sera from younger children were due to the presence in them of the antibodies cros ... | 1982 | 7090338 |
| [course of influenza in cyclophosphane suppression of cellular and humeral immunity]. | under conditions of immunosuppression of b- and t-cell functions with cyclophosphane, experimental influenza in mice infected with a/aichi/2/68 (h3n2) runs early in the infection a much milder course than in mice given no such treatment. the mortality among immunosuppressed mice was 5 times as low as in the controls; the virus could be isolated from the lung tissue earlier and in higher titres; cyclophosphane inhibited the synthesis of antibodies and nonspecific thermolabile and thermostable tis ... | 1982 | 7090340 |
| [characteristics of the degree and spectrum of antiviral activity of 2-(1'-aminoethyl)-bicyclo[2.2.1]heptane hydrochloride]. | a high activity of a bicycloheptane derivative against influenza viruses, poor activity against venezuelan equine encephalomyelitis and parainfluenza type 3 viruses, and the lack of activity against herpes simplex, vaccinia, echo 6, adenovirus type 3 replicating in tissue cultures were demonstrated. the efficacy of the drug in orthomyxovirus infection of tissue culture includes the viruses with the antigenic formula a (h3n2) and a (h1n1), is poor with the a/pr8/34 (h0n1) virus, and lacking with ... | 1982 | 7090343 |
| [parent and recombinant influenza virus a strains differing in the degree of remantadine sensitivity]. | the pattern of inheritance in recombination of various degrees of sensitivity of influenza viruses to remantadine was studied and the genes responsible for the manifestation of this character with regard to the degree of the strain sensitivity to the inhibitor were determined. the results suggest that resistance to 10 microgram/ml remantadine in most cases was determined by the inheritance of the gene coding for the membrane protein, whereas the sensitivity to 10 microgram/ml remantadine most fr ... | 1982 | 7090347 |
| secretory and systemic immunological response in children infected with live attenuated influenza a virus vaccines. | an enzyme-linked immunosorbent assay was used to measure isotype-specific antibody to purified hemagglutinin (ha) of influenza a virus, using serum and nasal-wash specimens from young children undergoing primary infection with live cold-adapted influenza a/alaska/77 (h3n2) or a/hong kong/77 (h1n1) candidate vaccine virus. the serum antibody response followed the pattern expected for a primary viral infection. each of 17 vaccinated children had a serum immunoglobulin g (igg) ha antibody response, ... | 1982 | 7095844 |
| influenza virus replication in human alveolar macrophages. | studies with animal models suggest that alveolar macrophages may be important cells in some respiratory virus infections, but little is known about the role of these cells in virus infections in man. in this study human alveolar macrophages were obtained by fibreoptic bronchoscopy and infected in vitro with a variety of influenza viruses. after infection with the nws strain of influenza virus the haemagglutinin and nucleoprotein viral antigens were demonstrated in greater than 90% of cells at 24 ... | 1982 | 7097255 |
| identification of naturally occurring temperature-sensitive strains of influenza a virus and location of their genetic lesions. | influenza a viruses of different subtypes isolated in different years and from different parts of china were examined for temperature-sensitiveness (ts) in their early egg passages. the validity of ts character has been confirmed by the results of parallel tests in chick embryos and in cell cultures. from 12 strains of the old h1n1 subtype isolated between 1949 and 1957, no ts strain was detected. two out of 6 strains of new h1n1 isolated after february 1979 were found to be ts. for the h3n2 sub ... | 1982 | 7100902 |
| the possible origin of h3n2 influenza virus. | | 1982 | 7101733 |
| anti-influenza a virus activity of amantadine hydrochloride and rimantadine hydrochloride in ferret tracheal ciliated epithelium. | the activities and toxicities of amantadine hydrochloride and rimantadine hydrochloride against influenza a/alaska/6/77 (h3n2) and a/bangkok/1/79 (h3n2) viruses were compared in organ cultures and ferret tracheal ciliated epithelium. pretreatment of cultures with concentrations (0.5 and 1 micrograms/ml) comparable to those found in human serum after oral administration of amantadine revealed that rimantadine produced significantly longer protection than amantadine against virus-induced cytopathi ... | 1982 | 7103458 |
| influenzavirus infections in seattle families, 1975-1979. i. study design, methods and the occurrence of infections by time and age. | intensive surveillance of seattle, washington, families with school-age children for influenzavirus infections during 1975-1979 encompassed 639 family- and 2732 person-seasons of observation, covering four influenzavirus epidemic seasons: type b (1975-1979), type a/h3n2 (1975-1976 and 1977-1978) and type a/h1n1 (1978-1979). late spring "herald" waves of infection occurred in 1977 (a/h3n2), 1978 (a/h1n1) and 1979 (type b), the latter presaging an epidemic in 1979-1980. out-of-season infections, r ... | 1982 | 7114033 |
| [antibody response to trivalent anti-influenza vaccination (inactivated virus) a/texas/1/77 h3n2), a/urss/90/77 (h1n1), b/hong kong/8/73]. | seventy-five young recruits received an intramuscular dose of anti-influenza virus vaccine containing 300 u.i. of a/texas/1/77 (h3n2), a/urss/90/77 (h1n1), b/hong kong/8/73 strains. antibody responses were detected by hi and srh tests: immunogenicity of the preparation was different for the individual vaccine strain in spite of the similar amount of antigenic content, and the immunity conferred by vaccine strains did not significantly extend to new influenza virus strains which prevailed in 1979 ... | 1982 | 7126342 |
| [antibody response to an anti-influenza vaccine of inactivated whole virus, titrated in micrograms, used in the 1980/81 season]. | antibody response of 68 healthy young-adult volunteers to a/bangkok/1/79 (h3n2), a/brazil/11/78 (h1n1), b/singapore/222/79 trivalent anti-influenza virus vaccine was studied by haemagglutination inhibition and single radial haemolysis techniques. the results of this study indicate that immunogenicity of the individual components of the vaccine (10 micrograms each) varied significantly, the highest frequence of antibody response occurring for a/brazil influenza virus strain and the lowest for b/s ... | 1982 | 7126343 |
| [retrospective identification of time of isolation of variants of a/bangkok/1/79 and a/beijing/2/79 group of h3n2 influenza virus]. | | 1982 | 7128321 |
| virulence of avian influenza a viruses for squirrel monkeys. | ten serologically distinct avian influenza a viruses were administered to squirrel monkeys and hamsters to compare their replication and virulence with those of human influenza a virus, a/udorn/307/72 (h3n2). in squirrel monkeys, the 10 avian influenza a viruses exhibited a spectrum of replication and virulence. the levels of virus replication and clinical response were closely correlated. two viruses, a/mallard/ny/6874/78 (h3n2) and a/pintail/alb/121/79 (h7n8), resembled the human virus in thei ... | 1982 | 7129631 |
| cellular response in humans following vaccination with gripax influenza virus. | cellular response of peripheral blood lymphocytes to influenza antigens was measured in a group of young nurse-student volunteers (17-24 years old), following vaccination with a formol-inactivated trivalent influenza vaccine (gripax). cord blood lymphocytes (controls) did not react with any of the antigens. this excluded the possibility of any nonspecific mitogenicity of viral antigens. viability of the cells was indicated by their responsiveness to phytohemagglutinin (pha). prior to immunizatio ... | 1982 | 7130968 |
| [variability of the virulent properties of influenza a viruses in recombination]. | the pattern of redistribution of human virulence in epidemic strains of influenza viruses in recombination with human avirulent strains was studied. in the course of recombination of epidemic and attenuated influenza virus strains variants with different human virulence were obtained. some recombinants manifested enforced reactogenic properties as compared with the epidemic strain (x/28, m/35, and 0/26--h1n1, and 2p--h3n2). at the same time, recombinants no 19 (h1n1) and 1p (h3n2) with a similar ... | 1982 | 7135925 |
| live influenza a/victoria/75 (h3n2) virus vaccines: reactogenicity, immunogenicity, and protection against wild-type virus challenge. | four live influenza a/victoria/75 (h3n2) recombinant virus vaccines were administered intranasally to a total of 50 volunteers who had little or no detectable serum neutralizing antibody. a recombinant with ts-1[e] having a 38 degrees c shut-off temperature caused febrile reactions or systemic reactions or both in 21% of the volunteers, but one with ts-1a2 having a 37 degrees c shut-off temperature caused no illness. two recombinants prepared with cold-adapted a/ann arbor/6/60 caused 9% febrile ... | 1982 | 7141686 |
| oligopeptide mapping of np proteins of influenza a viruses. | oligopeptide mapping of nucleoproteins (np proteins) of 54 strains of influenza a virus showed the presence of both common and individual oligopeptides. using the distribution of variable oligopeptides as the criterion, np proteins were subdivided into four groups (np0, np1, np2 and np3). the np0 group is composed of h0n1 influenza viruses and the majority of animal influenza viruses. the np1 group contains h1n1 (except a/california/78) and h2n2 influenza viruses isolated from man as well as h1n ... | 1982 | 7142966 |
| [neuraminidase of influenza virus]. | neuraminidase or sialidase (ec 3.2.1.18, acylneuraminyl hydrolase) from a strain of the influenza virus a (h3n2), identical to the a/hong kong/68 (h3n2) strain, has been purified and characterized by electrofocusing; only about 20% of the previous enzymic activity was lost after electrofocusing. the enzyme activity was measured by the peryodate-thiobarbiturate procedure, by the methoxyphenol-antipyrine method, and by spectrophotometry at 340 nm of the nadh produced in the oxidation of the beta-g ... | 1982 | 7146596 |
| demonstration of influenza virus reproduction stages sensitive to remantadine. | the antiviral action of remantadine was studied in bovine embryo kidney cells infected with influenza virus a/victoria 35/72(h3n2-3). the drug was administered at different stages of influenza virus reproduction. remantadine at a concentration of 50 micrograms/ml did not inhibit the activities of nuclear dna-dependent rna polymerase and of virion and virus-induced polymerases. remantadine was found to inhibit the synthesis of influenza virus rna at the stages of transcription and replication. | 1980 | 7189620 |
| serologic responses to nonprevalent influenza a viruses during intercyclic periods. | sera collected at different times in the course of the tecumseh study of respiratory illness have been tested for the presence of antibodies to a variety of nonprevalent human and animal type a influenza viruses. in sera collected during the 1966-1968 period of h2n2 prevalence, rises in antibody titer were detected against the h3 antigen. the frequency of these rises in titer increased gradually and significantly as the time of emergence of the h3n2 virus approached. occasional rises in hsw1 ant ... | 1981 | 7193408 |
| neuraminidase from influenza virus a (h3n2): specificity towards several substrates and procedure of activity determination. | neuraminidase (acylneuraminyl hydrolase, ec 3.2.1.18) from the influenza virus a/hong kong/68 (h3n2) was purified after treatment of the purified virus with sarcosyl (sodium laurylsarcosinate), centrifugation at 110 000 x g, and chromatography on deae-sephadex and sephadex g-200. it migrated as a single component during electrophoresis on polyacrylamide gel, and its molecular weight was estimated about 270 000. the enzyme was thermolabile, the activity being reduced to 60% in 10 min at 50 degree ... | 1980 | 7213637 |
| evaluation of influenza a/hong kong/123/77 (h1n1) ts-1a2 and cold-adapted recombinant viruses in seronegative adult volunteers. | two attenuated influenza a donor viruses, the a/udorn/72 ts-1a2 and the a/ann arbor/6/60 cold-adapted (ca) viruses, are being evaluated for their ability to reproducibly attenuate each new variant of influenza a virus to a specific and desired level by the transfer of one or more attenuating genes. each of these donor viruses has been able to attenuate influenza a viruses belonging to the h3n2 subtype by the transfer of one or more attenuating genes. to determine whether these two donor viruses ... | 1980 | 7216417 |
| outcome of influenza infection: effect of site of initial infection and heterotypic immunity. | an infection established throughout the total respiratory tract of mice with a highly lung adapted influenza virus (h0n1) led to death from viral pneumonia. the 50% lethal dose (ld(50)) was approximately the same as the 50% infectious dose (id(50)). an infection with the same virus initiated in the nasal mucosa spread to the trachea and lungs over a 3- to 5-day period but was not lethal except at very high infecting doses. the ld(50) was 30,000 times the id(50). mice that had recovered from a pr ... | 1980 | 7216433 |
| influenza and corona-virus antibodies in the newborns and their mothers in mali (1980). | in february 1980 blood samples from 91 women and their newborn babies (cord blood) from mali have been analysed for influenza and corona oc 43 hi antibodies. the titers of influenza hi antibodies were higher in blood samples collected from the mothers at delivery than in their newborns. considering the gmt values and percentage of persons with protective titers (greater than or equal to 1:40) we may assume that influenza a (h3n2) viruses had been highly active in mali. influenza a (h1n1) and b a ... | 1980 | 7233536 |
| [epidemic of influenza in antananarivo (with isolation of virus a/texas/77 (h3n2))]. | | 1980 | 7235771 |
| sequence of dna complementary to a small rna segment of influenza virus a/nt/60/68. | a small rna segment from the influenza virus strain a/nt/60/68 (h3n2) was converted to cdna and then to double-stranded dna using synthetic oligodeoxynucleotide primers. the double-stranded form was cloned into the bacteriophage m1 3mp7. clones yielding single-strand recombinant templates in opposite orientation were sequenced by the sanger dideoxynucleotide chain termination technique. the small viral rna was 422 nucleotides long and the evidence indicated that it was formed by internal deletio ... | 1981 | 7243594 |
| investigations on the risk of virus infection in dental surgery. preliminary data. | four virus strains -- influenza a/texas 1/77 (h3n2) an a/ussr 90/77 (h1n1), adenovirus and parainfluenza type 2 -- were isolated from different specimens collected in dental surgery rooms. high levels of antibodies to respiratory viruses (influenza, parainfluenza 1, 2 and 3), adeno-, cytomegalic and herpes viruses, as well as the presence of hbsag and anti-hbs could be detected in sera from patients hospitalized for dento-maxillofacial surgery. an epidemiological survey among dentists and dental ... | 1981 | 7245605 |
| evaluation of a/alaska/6/77 (h3n2) cold-adapted recombinant viruses derived from a/ann arbor/6/60 cold-adapted donor virus in adult seronegative volunteers. | the influenza a/ann arbor/6/60 (h2n2) cold-adapted (ca) virus was evaluated as a donor of attenuating genes to new variants of influenza a virus. this ca donor virus was mated with the a/alaska/6/77 (h3n2) wild-type virus, and three a/alaska/6/77 (h3n2) ca recombinant viruses were produced. the parental origin of the genes in the three ca recombinants had been determined previously (2), and their virulence for adult seronegative volunteers was assessed in the present study to identify the genes ... | 1981 | 7251144 |
| conservation of the influenza virus membrane protein (m1) amino acid sequence and an open reading frame of rna segment 7 encoding a second protein (m2) in h1n1 and h3n2 strains. | | 1981 | 7257189 |
| [grouping of influenza a virus np proteins]. | a comparative study of influenza a virus np proteins was carried out using peptide mapping. thirty-five strains of all main serotypes of human and animal viruses were tested. the greatest diversity was found in np proteins of human influenza viruses belonging to different serotypes, while within serotypes the variability is less pronounced. four main groups of np proteins were distinguished and designated np0, np1, np2, and np3. the np0 group includes proteins of viruses of hon1 serotype, np pro ... | 1981 | 7257320 |
| inactivated chromatographic influenza vaccine. | the characteristics of laboratory parameters of inactivated whole influenza virus vaccine, obtained by the purification of allantoic virus cultures on macroporous glass, are presented. the vaccine is characterized by small reactogenicity and safety, which allows it to be used in both adolescents and adults. seroconversions to hemagglutinin have been found in 80--95% of individuals vaccinated once during the test vaccination by the preparation containing various strains of influenza a/h3n2/virus. ... | 1981 | 7266085 |
| [comparative characteristics of influenza type a infection in adults and children during epidemics and interepidemic periods]. | parallel serological examinations by cft and hi test of paired sera from 18,557 patients and normal subjects in the period of influenza a/hong kong (h3n2) subtype virus in 1969-1976 revealed similar sensitivity of both methods for influenza diagnosis during epidemics, however in the interepidemic periods in these years the cft was found to be more sensitive than hi. this observation referred to all age groups of the examined subjects with manifest or asymptomatic forms of influenza infection. in ... | 1981 | 7269525 |
| principles of selective inactivation of viral genome. i. uv-induced inactivation of influenza virus. | photosensitivity of infectious, haemagglutinating and neuraminidase activities of influenza virus has been determined experimentally. the photosensitivity of infectious activity of type b (strain hongkong/8/73) influenza virus ws found to be higher than that of type a strains nib-4 (n3n2-3), leningrad/399/76 (h3n2-3) and nib-6 (h1n1). the data obtained may be used for the determination of conditions of uv-irradiation for preparation of uv-inactivated antiviral vaccines. | 1981 | 7271457 |
| a murine model for assessment of living attenuated influenza a vaccines. | the laboratory mouse was evaluated as a model to assess the genetic stability of influenza a mutants of potential use as living vaccine strains. the growth of three mutant recombinants, a/hong kong/68-ts-1e (h3n2), a/hk/123/77x-ts-1a2 (h1n1) and a2/aa/6/60-ca(h2n2) was studied in 15 g mice. yields of ts-1e from both lungs and turbinates were ten-fold less than that of a control virus with the same surface antigens. all ts-1e isolates showed evidence of loss of ts phenotype. ts-1a2 and ca recombi ... | 1980 | 7271601 |
| frequency of naturally occurring antibody to influenza virus antigenic variants selected in vitro with monoclonal antibody. | antigenic variants of a/texas/77 (h3n2) virus were selected in vitro using monoclonal antibody to virus haemagglutinin (ha). the antigenic variants and parental a/texas/77 viruses were used to to evaluate the frequency of anti-ha antibodies in the sera of children and adults using single-radial-haemolysis (srh) tests. twenty to 41% of selected sera from adults, which contained antibody to the parental a/texas/77 virus, failed to react with the different antigenic mutant viruses. a higher proport ... | 1981 | 7288173 |
| differential distribution of virus and histological damage in the lower respiratory tract of ferrets infected with influenza viruses of differing virulence. | the distribution of four strains of influenza virus [a/pr/8/34 (h0n1) and clone 64d (attenuated for ferrets) and clones 64c and 7a (virulent for ferrets) of the recombinant virus a/pr/8/34--a/england/939/69 (h3n2)] in the lower respiratory tract (trachea, bronchi and the hilar, intermediate and outer alveolar zones of the lung) of ferrets was monitored daily for 4 days after intranasal inoculation. on day 1, some animals had high virus titres in all the tissues but in other animals virus was und ... | 1981 | 7288401 |
| in vitro production of anti-influenza virus antibody after intranasal inoculation with cold-adapted influenza virus. | we have studied the production of anti-influenza virus antibody in vitro by peripheral blood mononuclear cells (pbmc) obtained from 7 normal volunteers at various times after intranasal inoculation with cold-adapted a/alaska/6/77 [h3n2] influenza virus. antibody released into culture supernatants was assayed by a 2-step enzyme-linked immunosorbent assay (elisa). cells obtained 6 days after intranasal inoculation spontaneously released both igg and iga anti-influenza antibody; this antibody produ ... | 1981 | 7299119 |
| study of recombinants derived from autochthonous influenza virus type a strains. | simultaneous inoculation of chick embryos with a standard laboratory influenza virus--a/pr8/34 (h0n1)--and with an autochthonous epidemic strain--belonging to the antigenic subtype a(h1n1) of a(h3n2), respectively--resulted in the isolation of two genetic recombinants, designated r1ivn (h1n1) and r2ivn (h3n2). each recombinant was antigenically identical to its wild-type parent and exhibited a hemagglutinating titer in chick embryos about 4-fold greater than that of the autochthonous parental st ... | 1981 | 7303494 |
| intratypic electrophoretic variation of structural and non-structural polypeptides of human influenza a viruses. | intratypic electrophoretic mobility differences in high resolution sds-polyacrylamide gels were detected between corresponding matrix (m) proteins, nucleoproteins (np), haemagglutinin (ha) and the non-structural polypeptides ns1 and ns2 induced in vero cells by human influenza a viruses of the antigenic subtypes h1n1 and h3n2. such phenotypic differences were distinguishable in both h1n1 and h3n2 viruses isolated in single school and city outbreaks. additional intratypic variation was detected i ... | 1981 | 7310381 |
| isolation and serological characterization of influenza a virus from a pig in thailand. | a hemagglutinating agent was isolated from a pig in thailand in 1978 during the early febrile stage of an influenza-like illness and identified as influenza a virus. the isolate contained hemagglutinin and neuraminidase antigens that were antigenically indistinguishable from those of a/tokyo/6/73 (h3n2), a port chalmers-like strain isolated in japan. serological tests also indicated that prevalence of h3n2 virus in the swine population in thailand. | 1981 | 7311111 |
| [role of mutations and recombinations in the epidemiology of influenza]. | influenza virus demonstrates several levels of antigenic variations, drifts and shifts, which help it to escape to herd immunity pressures. recent examples show the importance of such variations in the succession and continuity of epidemiological manifestations. during the last few years, simultaneous circulation of several subtypes of influenza a was observed while in the past, one subtype was replacing the other. thus in 1981, for the only subtype h3n2, a/texas, a/bangkok and a/intermediate te ... | 1981 | 7316613 |
| [epidemiological characteristics of influenza caused by the a(h3n2) virus in moldavia between 1969 and 1980]. | | 1981 | 7330563 |
| growth of avian and human influenza viruses in organ cultures of duck and chicken colons. | colons from ducks and chicken 1, 7, 14 and 28 days old maintained near-normal morphology up to 48 and 96 hours respectively in a system using nctc135 medium (a part) + dulbecco's modified eagle's medium (9 parts ), at 37 degrees c and 95 per cent o2/5 per cent co2. in the colon of 1 and 28 day-old ducks, duck influenza virus (hav7n2) and budgerigar influenza virus (hav4nav1) grew to peak titer by hour 72, whereas human influenza virus (h3n2) did not grow. in the colon of 1 day-old chicken, the t ... | 1981 | 7332490 |
| comparative immunogenicity of live influenza viruses and their solubilized neuraminidases: results of mouse protection experiments. | antigenicity and immunogenicity of three influenza virus strains a/pr/8/34 (h1n1). a/hong kong/1/68 (h3n2) and a/port chalmers/1/73 (h-3h2) were assayed comparatively with their corresponding neuraminidase isolated by proteolysis, and with the recombinant virus x-42 (heq1 n2). it was concluded that intranasal immunization of mice with live virus induced heterologous immunity. except in homologous neuraminidase-vaccinated mice, the subunit always was shown less effective and demonstrated a signif ... | 1981 | 7332493 |
| [comparative study of the polypeptide composition of influenza a viruses sensitive and resistant to remantadine]. | the polypeptide composition of influenza a fpv (hav1n1) and a/texas/1/77 (h3n2) viruses which had acquired resistance to remantadine after serial passages in cell cultures in the presence of the drug was studied. it was found that in parallel with the acquired resistance to remantadine the molecular weight of the heavy chain of hemagglutinin changed only in the course of cell culture passages. the influenza a/texas/1/77 virus passaged in chick embryos in the presence of remantadine exhibited no ... | 1981 | 7336680 |
| [results of a study of collective immunity to influenza a virus (h1n1) from 1976 to 1980]. | the time course of the levels of circulating antihemagglutinins to influenza a (h1n1) virus in the populations of the towns in different geographical zones of the ussr was shown to be similar. the intensity of herd immunity in some areas differed considerably, however. the population of older age groups most of whom had no clinically manifest diseases during the influenza a (h1n1) epidemic was shown to experience immunological changes upon exposure to this agent. the intensity and the rate of ch ... | 1981 | 7336683 |
| [grouping of the ns1 nonstructural proteins of influenza a viruses]. | peptide mapping was used for comparative analysis of nonstructural proteins (ns1) of 21 strains of human and animal influenza a viruses. at least 4 groups of ns1 proteins could be distinguished by the analysis of the peptide maps; we designated these groups as 0, 1, 2, and 3. group o includes ns1 proteins of human influenza virus serotype hon1, group 1 - ns1 proteins of viruses of serotypes h1n1 and h2n2, group 2 - ns1 proteins of viruses of serotype h3n2. ns1 proteins of avian influenza viruses ... | 1981 | 7336689 |
| [cross protection in mice immunized with different anti-influenza preparations]. | observations in white mice demonstrated the development of resistance to influenza type a virus (h3n2 and h0n1) after vaccination against influenza a (h1n1). the most marked cross protection between these serotypes developed after combined use of inactivated and live moderately attenuated vaccines. the resistance to the homologous influenza a (h1n1) virus after vaccination with different influenza vaccines used by various schedules was approximately similar. the role of common antigens and cellu ... | 1981 | 7336695 |
| [biological relations of selected influenza virus strains adapted to mouse lungs. i. h3n2 influenza virus study]. | | 1980 | 7340409 |
| influenza a antibodies in cervine animals. | in the haemagglutination inhibition (hi) test, 20 cervine sera, most of which came from northern germany, were treated with receptor destroying enzyme (rde) and 11 sera were found to contain antibodies against the h1n1 (a/ussr 90/77) and h3n2 (a/victoria 13/75, a/texas 1/77) influenza viruses. only two sera contained antibodies against h3n2 viruses, and seven sera were negative. evidence of the specificity of influenza antibodies was provided by the following findings: 1) the igg serum extracts ... | 1980 | 7390623 |
| human trials with wild-type h1n1 and recombinant h3n2-h1n1 influenza a viruses of 1977-1978. | a series of trials was conducted in which wild-type a/ussr/90/77 (h1n1) influenza a virus and a few of its antigenic variants were inoculated into volunteers. infections readily occurred in people of all ages who had initial low antibody titers, but clinical effects were generally mild in comparison with those of the previously tested subtypes, h0n1, h1n1, h2n2, h3n2. there was, however, an inverse relationship between severity of symptoms and age of volunteers, although the incidence of virus e ... | 1980 | 7399693 |