Publications

subolesin expression in response to pathogen infection in ticks.	ticks (acari: ixodidae) are vectors of pathogens worldwide that cause diseases in humans and animals. ticks and pathogens have co-evolved molecular mechanisms that contribute to their mutual development and survival. subolesin was discovered as a tick protective antigen and was subsequently shown to be similar in structure and function to akirins, an evolutionarily conserved group of proteins in insects and vertebrates that controls nf-kb-dependent and independent expression of innate immune res ...	2010	20170494
differential expression of genes in salivary glands of male rhipicephalus (boophilus)microplus in response to infection with anaplasma marginale.	bovine anaplasmosis, caused by the rickettsial tick-borne pathogen anaplasma marginale (rickettsiales: anaplasmataceae), is vectored by rhipicephalus (boophilus)microplus in many tropical and subtropical regions of the world. a. marginale undergoes a complex developmental cycle in ticks which results in infection of salivary glands from where the pathogen is transmitted to cattle. in previous studies, we reported modification of gene expression in dermacentor variabilis and cultured ixodes scapu ...	2010	20298599
pyrosequencing and characterization of immune response genes from the american dog tick, dermacentor variabilis (l.).	ticks continue to be a threat to animal and human health, and new and novel control strategies are needed for ticks and tick-borne pathogens. the characterization of the tick-pathogen interface and the tick immune response to microbial infections is fundamental toward the formulation of new control strategies for ticks and the pathogens they transmit. our overall hypothesis for this research is that the tick immune system manages the maintenance of pathogens. therefore, discovery of tick immune ...	2010	20698900
silencing of genes involved in anaplasma marginale-tick interactions affects the pathogen developmental cycle in dermacentor variabilis.	the cattle pathogen, anaplasma marginale, undergoes a developmental cycle in ticks that begins in gut cells. transmission to cattle occurs from salivary glands during a second tick feeding. at each site of development two forms of a. marginale (reticulated and dense) occur within a parasitophorous vacuole in the host cell cytoplasm. however, the role of tick genes in pathogen development is unknown. four genes, found in previous studies to be differentially expressed in dermacentor variabilis ti ...	2009	19607704
silencing expression of the defensin, varisin, in male dermacentor variabilis by rna interference results in reduced anaplasma marginale infections.	antimicrobial peptides, including defensins, are components of the innate immune system in ticks that have been shown to provide protection against both gram-negative and gram-positive bacteria. varisin, one of the defensins identified in dermacentor variabilis, was shown to be produced primarily in hemocytes but transcript levels were also expressed in midguts and other tick cells. in this research, we studied the role of varisin in the immunity of ticks to the gram-negative cattle pathogen, an ...	2008	18523848
differential expression of the tick protective antigen subolesin in anaplasma marginale- and a. phagocytophilum-infected host cells.	subolesin was recently shown in vaccine and rna interference (rnai) studies to protect against tick infestations and to affect tick feeding, reproduction, and development as well as infection of host cells by anaplasma marginale and a. phagocytophilum. recent experiments provided evidence that infection of both tick and vertebrate host cells with these two pathogens modified gene expression. we therefore hypothesized that infection of host cells with a. marginale and a. phagocytophilum affects e ...	2008	19120168
conservation of transmission phenotype of anaplasma marginale (rickettsiales: anaplasmataceae) strains among dermacentor and rhipicephalus ticks (acari: ixodidae).	before the eradication of boophilus ticks from the united states, rhipicephalus (boophilus) microplus (canestrini) and rhipicephalus (boophilus) annulatus (say) were important biological vectors of the cattle pathogen anaplasma marginale theiler. in the absence of boophilus ticks, a. marginale continues to be transmitted by dermacentor ticks. however, a few u.s. strains are not transmissible by dermacentor andersoni stiles, dermacentor variabilis (say), or both, raising the question of how these ...	2007	17547235
experimental transmission of bovine anaplasmosis (caused by anaplasma marginale) by means of dermacentor variabilis and d. andersoni (ixodidae) collected in western canada.	canadian cattle are free of bovine anaplasmosis, with the exception of 4 isolated incursions since 1968, which were eradicated. it is not known why the disease has not become established in regions of canada adjacent to the united states where it is endemic. to assess the vector competence of wild-caught ticks in cattle-rearing regions, dermacentor variabilis and d. andersoni were collected in western canada and fed on calves experimentally infected with anaplasma marginale (st. maries strain). ...	2007	17955901
reduction of tick infections with anaplasma marginale and a. phagocytophilum by targeting the tick protective antigen subolesin.	subolesin was recently shown by both gene silencing and immunization with the recombinant protein to protect against tick infestations, and to cause reduced tick survival and degeneration of gut and salivary gland tissues. in this research, we extended these studies by testing whether targeting subolesin by rnai or vaccination interfered with the ability of ticks to become infected with two tick-borne pathogens, anaplasma marginale which causes bovine anaplasmosis and anaplasma phagocytophilum, ...	2006	16816958
distribution, seasonality, and hosts of the rocky mountain wood tick in the united states.	anaplasma marginale theiler is a tick-borne pathogen that causes anaplasmosis in cattle. there are approximately 20 tick species worldwide that are implicated as vectors of this pathogen. in the united states, dermacentor andersoni stiles and dermacentor variabilis (say) are the principal vectors. the risk of transmission of anaplasmosis to cattle has been largely based on the distribution of d. andersoni in the united states. we developed a centralized geographic database that incorporates coll ...	2006	16506443
capillary tube feeding system for studying tick-pathogen interactions of dermacentor variabilis (acari: ixodidae) and anaplasma marginale (rickettsiales: anaplasmataceae).	a capillary tube feeding (ctf) system was adapted for studying the interaction between dermacentor variabilis (say) and the rickettsial cattle pathogen anaplasma marginale theiler. a. marginale undergoes a complex developmental cycle in ticks that begins in midguts and ends by transmission from salivary glands. in this ctf system, male d. variabilis were fed a. marginale-infected blood or cultured tick cells. ticks that fed on highly rickettsemic calves developed midgut and salivary gland infect ...	2005	16366000
recent studies on the characterization of anaplasma marginale isolated from north american bison.	anaplasma marginale (rickettsiales: anaplasmataceae), a tick-borne pathogen of cattle, is endemic in tropical and subtropical regions of the world. many geographic isolates of a. marginale occur worldwide that have been identified by major surface protein (msp) 1a, which varies in sequence and molecular weight owing to different numbers of tandem 28-29 amino acid repeats. although serologic tests have identified american bison, bison bison, as being infected with a. marginale, the present studie ...	2004	15604478
co-feeding studies of ticks infected with anaplasma marginale.	ticks often cluster at preferred feeding sites on hosts, and the co-feeding of ticks at the same site has been shown to increase feeding success and the transmission of some pathogens. while the major route of infection of ticks with pathogens is via the bloodmeal during feeding on a parasitemic host, non-systemic transmission of viruses and spirochetes has been shown to occur from infected to uninfected ticks at common feeding sites on uninfected hosts. in this research, two separate studies we ...	2003	12623209
infection exclusion of the rickettsial pathogen anaplasma marginale in the tick vector dermacentor variabilis.	anaplasma marginale is a tick-borne, rickettsial cattle pathogen that is endemic in several areas of the united states. recent studies (j. de la fuente, j. c. garcia-garcia, e. f. blouin, j. t. saliki, and k. m. kocan, clin. diagn. lab. immunol. 9:658-668, 2002) demonstrated that infection of cultured tick cells and bovine erythrocytes with one genotype of a. marginale excluded infection with other genotypes, a phenomenon referred to as infection exclusion. the present study was undertaken to co ...	2003	12522060
vaccination of cattle with anaplasma marginale derived from tick cell culture and bovine erythrocytes followed by challenge-exposure with infected ticks.	anaplasmosis, a hemolytic disease of cattle caused by the tick-borne pathogen anaplasma marginale (rickettsiales: anaplasmataceae) has been controlled using killed vaccines made with antigen harvested from infected bovine erythrocytes. we recently developed a cell culture system for propagation of a. marginale in a continuous tick cell line. in this study, we performed a cattle trial to compare the bovine response to vaccination with a. marginale harvested from tick cell culture or bovine erythr ...	2002	12243900
conservation of major surface protein 1 genes of anaplasma marginale during cyclic transmission between ticks and cattle.	bovine anaplasmosis is a rickettsial disease of world-wide economic importance caused by anaplasma marginale. several major surface proteins with conserved gene sequences have been examined as potential candidates for vaccines and/or diagnostic assays. major surface protein 1 (msp1) is composed of polypeptides msp1a and msp1b. msp1a is expressed from the single copy gene msp1 alpha and msp1b is expressed by members of the msp1 beta multigene family. in order to determine if the msp1 genes are co ...	2002	11814681
major surface protein 1a effects tick infection and transmission of anaplasma marginale.	anaplasma marginale, an ehrlichial pathogen of cattle and wild ruminants, is transmitted biologically by ticks. a developmental cycle of a. marginale occurs in a tick that begins in gut cells followed by infection of salivary glands, which are the site of transmission to cattle. geographic isolates of a. marginale vary in their ability to be transmitted by ticks. in these experiments we studied transmission of two recent field isolates of a. marginale, an oklahoma isolate from wetumka, ok, and a ...	2001	11730800
expression of anaplasma marginale major surface protein 2 variants in persistently infected ticks.	anaplasma marginale, an intraerythrocytic ehrlichial pathogen of cattle, establishes persistent infections in both vertebrate (cattle) and invertebrate (tick) hosts. the ability of a. marginale to persist in cattle has been shown to be due, in part, to major surface protein 2 (msp2) variants which are hypothesized to emerge in response to the bovine immune response. msp2 antigenic variation has not been studied in persistently infected ticks. in this study we analyzed msp2 in a. marginale popula ...	2001	11447197
molecular phylogeny and biogeography of north american isolates of anaplasma marginale (rickettsiaceae: ehrlichieae).	anaplasma marginale (a. marginale) is a tick-borne ehrlichial pathogen of cattle that causes the disease anaplasmosis. six major surface proteins (msps) have been identified on a. marginale from cattle and ticks of which three, msp1a, msp4 and msp5, are from single genes and do not vary within isolates. the other three, msp1b, msp2 and msp3, are from multigene families and may vary antigenically in persistently infected cattle. several geographic isolates have been identified in the united state ...	2001	11337128
differential adhesion of major surface proteins 1a and 1b of the ehrlichial cattle pathogen anaplasma marginale to bovine erythrocytes and tick cells.	anaplasma marginale is a tick-borne ehrlichial pathogen of cattle for which six major surface proteins (msps) have been described. the msp1 complex, a heterodimer composed of msp1a and msp1b, was shown to induce a protective immune response in cattle and both proteins have been identified as putative adhesins for bovine erythrocytes. in this study the role of msp1a and msp1b as adhesins for bovine erythrocytes and tick cells was defined. msp1alpha and msp1beta1 genes from the oklahoma isolate of ...	2001	11239934
transstadial and attempted transovarial transmission of anaplasma marginale by dermacentor variabilis.	transstadial and transovarial transmission of anaplasma marginale by dermacentor variabilis were attempted with with ticks exposed to the organism once by feeding as larvae or nymphs, and twice by feeding as larvae and nymphs. typical colonies of a marginale were in gut tissues of adults that were infected as larvae, larvae and nymphs, and as nymphs; repeated exposure of ticks did not appear to result in an increase in the number of colonies in the gut of subsequently molted adults nor did it af ...	1989	2782719
anaplasma marginale in tick cell culture.	anaplasma marginale was propagated in a tick cell line derived from dermacentor variabilis embryos. the rickettsial organism was identified and monitored in culture by transmission electron microscopy and the indirect immunofluorescence technique, using specific monoclonal antibodies. inoculation of the embryonic tick cell line with midguts of infected adult ticks (culture 1), nymphal ticks (culture 2) and adult ticks that were infected as nymphs and dissected as adults (culture 3) resulted in 3 ...	1989	2692483
infectivity and antigenicity of anaplasma marginale from tick cell culture.	the infectivity and immunogenicity of anaplasma marginale grown in a tick cell culture from embryonic dermacentor variabilis ticks were assessed in splenectomized and intact calves, respectively. culture 1 consisted of the cell line inoculated with midguts of adult ticks infected with the mississippi isolate of a marginale and dissected 5 to 10 days after repletion and detachment from an experimentally infected calf. cultures 2 and 3 consisted of the cell line inoculated with midguts of ticks in ...	1989	2610428
cultivation of anaplasma marginale from cattle in a dermacentor cell line.	a tick cell line derived from dermacentor variabilis (rml-15) was inoculated with bovine rbc infected with anaplasma marginale. two hours after inoculation, numerous rbc were phagocytized by the tick cells. after one passage of the cell culture, numerous groups of anaplasma-like particles were seen in the tick cell cytoplasm. increased numbers of anaplasma-like particles also were present. seemingly, anaplasma can multiply in tick cells.	1988	3348535
persistence of colonies of anaplasma marginale in overwintering dermacentor variabilis.	dermacentor variabilis were infected as nymphs with anaplasma marginale by allowing the ticks to feed on a single infected donor calf. two weeks after molting to the adult stage, the ticks were allotted into 1 of 3 groups and were allowed to overwinter at room temperature (25 c) in the laboratory (group 1), cold storage (4.5 c) in the laboratory (group 2), or outdoors in leaf litter (group 3). persistence of a marginale was assessed by determining density of colonies (number of colonies/0.1 mm2 ...	1987	3592362
isolate of anaplasma marginale not transmitted by ticks.	the tick-borne transmissibility of 2 isolates of anaplasma marginale was compared. dermacentor variabilis were exposed to a marginale as nymphs by feeding on 1 of 4 splenectomized calves during periods of ascending parasitemia (maximum 49% to 81% parasitized erythrocytes) induced by injection of a stabilate. tick-borne transmission was attempted, using 26 to 224 adult ticks within 30 to 220 days after molting. adult d variabilis did not transmit an illinois isolate of a marginale in 7 tick-borne ...	1986	3946891
transmission of anaplasma marginale theiler by dermacentor andersoni stiles and dermacentor variabilis (say).	cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles and d variabilis (say) nymphs. following a molt and subsequent feeding of adult ticks on susceptible cows, transstadial transmission of a marginale occurred from cattle with parasitemias ranging from undetectable (in a carrier cow) to a peak of 27% (in an acutely ill cow). homogenates of gut tissue from unfed, incubated, and feeding ad ...	1981	7224310
demonstration of anaplasma marginale theiler in dermacentor variabilis (say) by ferritin-conjugated antibody technique.	cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor variabilis (say) nymphs. transstadial transmission of a marginale was demonstrated by feeding the newly molted adult ticks on susceptible cattle and by inoculation of gut homogenates collected from adult ticks at postattachment day 6. a similar gut homogenate from the same group of ticks was caused to react with a marginale-bovine antisera that had bee ...	1980	7212431
ultrastructure of anaplasma marginale theiler in dermacentor andersoni stiles and dermacentor variabilis (say).	cattle were inoculated with a virginia isolate of anaplasma marginale theiler and served as an infective source for laboratory-reared dermacentor andersoni stiles and d variabilis (say) nymphs. anaplasma marginale was demonstrated by electron microscopy in gut tissues of replete nymphal ticks and in unfed, incubated, and feeding adult ticks that were exposed to the organism as nymphs when they fed on an infected cow. the a marginale organism in replete nymphs and adult feeding ticks were morphol ...	1980	7212430