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Cook SJ, Li G, Zheng Y, Willand ZA, Issel CJ, Cook RF. Molecular Characterization of the Major Open Reading Frames (ORFs) and Enhancer Elements From Four Geographically Distinct North American Equine Infectious Anemia Virus (EIAV) Isolates. J Equine Vet Sci 2019; 85:102852. [PMID: 31952638 DOI: 10.1016/j.jevs.2019.102852] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/01/2019] [Accepted: 11/08/2019] [Indexed: 02/05/2023]
Abstract
Although the equine lentivirus (equine infectious anemia virus [EIAV]) poses a major threat to equid populations throughout most regions of the world, detailed knowledge concerning its molecular epidemiology is still in its infancy. Such information is important because the few studies conducted to date suggest there is extensive genetic variation between viral isolates that if confirmed has significant implications for future vaccine design and development of newer diagnostic procedures. Here, we avoid potential assembly artifacts inherent in composite sequencing techniques by using long-range PCR in conjunction with next-generation sequencing for the rapid molecular characterization of all major open reading frames (ORFs) and known transcription factor binding motifs within the long terminal repeats (LTRs) of four North American EIAV isolates from Pennsylvania (EIAVPA), Tennessee (EIAVTN), North Carolina (EIAVNC), and Florida (EIAVFL). These were compared with complete published EIAV field strain genomic sequences from Asia (EIAVLIA, EIAVMIY), Europe (EIAVIRE), and North America (EIAVWY) plus EIAVUK a laboratory variant of EIAVWY. Phylogenetic analysis using the long-range PCR products suggested all the New World EIAV isolates comprised a single monophyletic group associated with EIAVIRE. This is distinct from the Asian isolates and so consistent with known historical details concerning the reintroduction of equids into North America by European settlers. Nonetheless nucleotide sequence identity for example between EIAVPA and EIAVTN, EIAVNC, EIAVFL, EIAVWY, EIAVUK plus EIAVIRE was limited to 84.6%, 81.0%, 82.1%, 80.4%, 80.1%, and 77.6%, respectively, with some of these values being not too dissimilar to those between EIAVPA and EIAVLIA or EIAVMIY at 78.0% and 75.4%, respectively. Overall, these results suggest substantial genetic diversity exists even within North American EIAV isolates. Comparative alignment of predicted amino acid sequences from all strains provides increased understanding concerning the extent of permitted substitutions in each viral ORF and known transcriptional LTR control elements.
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Affiliation(s)
- Sheila J Cook
- Department of Veterinary Science, Maxwell-Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - Ganwu Li
- NGS Unit, Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Ying Zheng
- NGS Unit, Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Zachary A Willand
- Department of Veterinary Science, Maxwell-Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - Charles J Issel
- Department of Veterinary Science, Maxwell-Gluck Equine Research Center, University of Kentucky, Lexington, KY
| | - R Frank Cook
- Department of Veterinary Science, Maxwell-Gluck Equine Research Center, University of Kentucky, Lexington, KY.
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Cook RF, Barrandeguy M, Lee PYA, Tsai CF, Shen YH, Tsai YL, Chang HFG, Wang HTT, Balasuriya UBR. Rapid detection of equine infectious anaemia virus nucleic acid by insulated isothermal RT-PCR assay to aid diagnosis under field conditions. Equine Vet J 2018; 51:489-494. [PMID: 30353944 DOI: 10.1111/evj.13032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/24/2018] [Indexed: 12/24/2022]
Abstract
BACKGROUND Control of equine infectious anaemia (EIA) currently depends on serological diagnosis of infected equids. However, recently infected equids may not produce detectable anti-EIAV antibodies up to 157 days post infection and so present a high transmission risk. Therefore, direct nucleic acid detection methods are urgently needed to improve EIAV surveillance and management programs in counties where the disease is endemic. OBJECTIVES To evaluate a field-deployable, reverse transcription-insulated isothermal PCR (RT-iiPCR) assay targeting the conserved 5' untranslated region (5' UTR)/exon 1 of the tat gene of EIAV. STUDY DESIGN The analytical and clinical performance of the newly developed EIAV RT-iiPCR was evaluated by comparison with a EIAV real-time RT-PCR (RT-qPCR) along with the AGID test. METHODS Analytical sensitivity was determined using in vitro transcribed RNA containing the target area of the 5' UTR/tat gene and samples from two EIAV-positive horses. Specificity was verified using nine common equine viruses. Clinical performance was evaluated by comparison with EIAV RT-qPCR and AGID using samples derived from 196 inapparent EIAV carrier horses. RESULTS EIAV RT-iiPCR did not react with other commonly encountered equine viruses and had equivalent sensitivity (95% detection limit of eight genome equivalents), with a concordance of 95.41% to conventional EIAV RT-qPCR. However, the RT-qPCR and RT-iiPCR had sensitivities of 43.75 and 50.00%, respectively, when compared to the AGID test. MAIN LIMITATIONS Low viral loads commonly encountered in inapparent EIAV carriers may limit the diagnostic sensitivity of RT-PCR-based tests. CONCLUSIONS Although EIAV RT-iiPCR is not sufficiently sensitive to replace the current AGID test, it can augment control efforts by identifying recently exposed or "serologically silent" equids, particularly as the latter often represent a significant transmission risk because of high viral loads. Furthermore, the relatively low cost and field-deployable design enable utilisation of EIAV RT-iiPCR even in remote regions.
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Affiliation(s)
- R F Cook
- Louisiana Animal Disease Diagnostic Laboratory and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA
| | - M Barrandeguy
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Virología, Argentina
| | - P-Y A Lee
- GeneReach USA, Lexington, Massachusetts, USA
| | - C-F Tsai
- GeneReach USA, Lexington, Massachusetts, USA
| | - Y-H Shen
- GeneReach USA, Lexington, Massachusetts, USA
| | - Y-L Tsai
- GeneReach USA, Lexington, Massachusetts, USA
| | - H-F G Chang
- GeneReach USA, Lexington, Massachusetts, USA
| | - H-T T Wang
- GeneReach USA, Lexington, Massachusetts, USA
| | - U B R Balasuriya
- Louisiana Animal Disease Diagnostic Laboratory and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA
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Horses naturally infected with EIAV harbor 2 distinct SU populations but are monophyletic with respect to IN. Virus Genes 2016; 52:71-80. [PMID: 26739458 DOI: 10.1007/s11262-015-1280-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 12/19/2015] [Indexed: 10/22/2022]
Abstract
Equine infectious anemia virus (EIAV) causes lifelong infections ranging from acutely fatal, to chronic, to asymptomatic. Within infected animals, EIAV is found as a quasispecies. Many experimental studies on EIAV, carried out in the U.S. over the past 70 years, have used either the highly virulent Wyoming (EIAVWYO) field strain or various derivatives of that strain. These infections have provided insights into the variety of genetic changes that accumulate in the env gene and LTR in experimentally infected horses. In the current study, we obtained EIAV sequences from blood samples collected from naturally infected Texas horses between 2000 and 2002. We found surface (SU) and long terminal repeat (LTR) sequences clearly related to EIAVWYO and its cell culture-adapted derivatives. Some blood samples yielded SU or LTR sequences belonging to 2 discrete clusters. In these cases, SU and LTR variation between animals was no greater than sequence variation within animals. In contrast, a portion of integrase (IN) was more homogeneous within animals than between animals. These results suggest that specific selective pressures are applied to SU and LTR sequences, potentially driving generation of two distinct sequence clusters within a horse. We speculate that viruses in one cluster may be more highly expressed and easily transmitted while those in the second cluster support long-term inapparent infection. The presence of homogeneous IN sequences within a horse supports the hypothesis that SU and LTR sequences diverged after the initial infection.
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Comparative analysis of LTR and structural genes in an equine infectious anemia virus strain isolated from a feral horse in Japan. Arch Virol 2014; 159:3413-20. [DOI: 10.1007/s00705-014-2206-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 08/17/2014] [Indexed: 11/25/2022]
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Cook R, Leroux C, Issel C. Equine infectious anemia and equine infectious anemia virus in 2013: A review. Vet Microbiol 2013; 167:181-204. [DOI: 10.1016/j.vetmic.2013.09.031] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 09/16/2013] [Accepted: 09/21/2013] [Indexed: 10/26/2022]
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Molecular detection, epidemiology, and genetic characterization of novel European field isolates of equine infectious anemia virus. J Clin Microbiol 2010; 49:27-33. [PMID: 21084503 DOI: 10.1128/jcm.01311-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The application of molecular diagnostic techniques along with nucleotide sequence determination to permit contemporary phylogenetic analysis of European field isolates of equine infectious anemia virus (EIAV) has not been widely reported. As a result, of extensive testing instigated following the 2006 outbreak of equine infectious anemia in Italy, 24 farms with a history of exposure to this disease were included in this study. New PCR-based methods were developed, which, especially in the case of DNA preparations from peripheral blood cells, showed excellent correlation with OIE-approved agar gel immunodiffusion (AGID) tests for identifying EIAV-infected animals. In contrast, the OIE-recommended oligonucleotide primers for EIAV failed to react with any of the Italian isolates. Similar results were also obtained with samples from four Romanian farms. In addition, for the first time complete characterization of gag genes from five Italian isolates and one Romanian isolate has been achieved, along with acquisition of extensive sequence information (86% of the total gag gene) from four additional EIAV isolates (one Italian and three Romanian). Furthermore, in another 23 cases we accomplished partial characterization of gag gene sequences in the region encoding the viral matrix protein. Analysis of this information suggested that most Italian isolates were geographically restricted, somewhat reminiscent of the "clades" described for human immunodeficiency virus type 1 (HIV-1). Collectively this represents the most comprehensive genetic study of European EIAV isolates conducted to date.
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Genetic variation in the long terminal repeat associated with the transition of Chinese equine infectious anemia virus from virulence to avirulence. Virus Genes 2009; 38:285-8. [PMID: 19130201 DOI: 10.1007/s11262-008-0317-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2008] [Accepted: 12/18/2008] [Indexed: 10/21/2022]
Abstract
A highly virulent strain of equine infectious anemia virus (EIAV) lost its fatal virulence but retained the desired antigens during serial passage over 130 generations in leukocytes in vitro. We compared the long terminal repeat (LTR) sequences of the different generations and found that three stable genetic variations occurred in the transcriptional start site, the initial base of TAR, and the pre-mRNA cleavage site at the R-U5 boundary, respectively. These three mutations happened at the inflexion of virus pathogenicity loss; therefore, the function of these mutations needs to be further addressed.
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Fidalgo-Carvalho I, Craigo JK, Barnes S, Costa-Ramos C, Montelaro RC. Characterization of an equine macrophage cell line: application to studies of EIAV infection. Vet Microbiol 2008; 136:8-19. [PMID: 19038510 DOI: 10.1016/j.vetmic.2008.10.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 10/06/2008] [Accepted: 10/13/2008] [Indexed: 11/26/2022]
Abstract
EIAV is a monocyte/macrophage tropic virus. To date, even though EIAV has been under investigation for numerous years, very few details have been elucidated about EIAV/macrophage interactions. This is largely due to the absence of an equine macrophage cell line that would support viral replication. Herein we describe the spontaneous immortalization and generation of a clonal equine macrophage-like (EML) cell line with the functional and immunophenotype characteristics of differentiated equine monocyte derived macrophage(s) (eMDM(s)). These cells possess strong non-specific esterase (NSE) activity, are able to phagocytose fluorescent bioparticles, and produce nitrites in response to LPS. The EML-3C cell line expresses the EIAV receptor for cellular entry (ELR1) and supports replication of the virulent EIAV(PV) biological clone. Thus, EML-3C cells provide a useful cell line possessing equine macrophage related properties for the growth and study of EIAV infection as well as of other equine macrophage tropic viruses.
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Affiliation(s)
- Isabel Fidalgo-Carvalho
- Iron Genes and the Immune System, Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, Oporto, Portugal
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Zhou T, Yuan XF, Hou SH, Tu YB, Peng JM, Wen JX, Qiu HJ, Wu DL, Chen HC, Wang XJ, Tong GZ. Long terminal repeat sequences from virulent and attenuated equine infectious anemia virus demonstrate distinct promoter activities. Virus Res 2007; 128:58-64. [PMID: 17499380 DOI: 10.1016/j.virusres.2007.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 03/31/2007] [Accepted: 04/03/2007] [Indexed: 11/29/2022]
Abstract
In the early 1970s, the Chinese Equine Infectious Anemia Virus (EIAV) vaccine, EIAV(DLA), was developed through successive passages of a wild-type virulent virus (EIAV(L)) in donkeys in vivo and then in donkey macrophages in vitro. EIAV attenuation and cell tropism adaptation are associated with changes in both envelope and long terminal repeat (LTR). However, specific LTR changes during Chinese EIAV attenuation have not been demonstrated. In this study, we compared LTR sequences from both virulent and attenuated EIAV strains and documented the diversities of LTR sequence from in vivo and in vitro infections. We found that EIAV LTRs of virulent strains were homologous, while EIAV vaccine have variable LTRs. Interestingly, experimental inoculation of EIAV(DLA) into a horse resulted in a restriction of the LTR variation. Furthermore, LTRs from EIAV(DLA) showed higher Tat transactivated activity than LTRs from virulent strains. By using chimeric clones of wild-type LTR and vaccine LTR, the main difference of activity was mapped to the changes of R region, rather than U3 region.
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Affiliation(s)
- Tao Zhou
- Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China
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Fagerness AJ, Flaherty MT, Perry ST, Jia B, Payne SL, Fuller FJ. The S2 accessory gene of equine infectious anemia virus is essential for expression of disease in ponies. Virology 2006; 349:22-30. [PMID: 16503341 DOI: 10.1016/j.virol.2005.12.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2005] [Revised: 11/12/2005] [Accepted: 12/22/2005] [Indexed: 10/25/2022]
Abstract
Equine infectious anemia virus (EIAV) is a macrophage-tropic lentivirus that persistently infects horses and causes a disease that is characterized by periodic episodes of fever, thrombocytopenia, and viremia. EIAV encodes only four regulatory/accessory genes, (tat, rev, ttm, and S2) and is the least genetically complex of all known lentiviruses. We sought to determine the role of the EIAV S2 accessory gene of EIAV by introducing mutations that would prevent S2 expression on the p19/wenv17 infectious molecular clone. Virus derived from the p19/wenv17 molecular clone is highly virulent and routinely fatal when given in high doses (J. Virol. 72 (1998) 483). In contrast, an S2 deletion mutant on the p19/wenv17 background is unable to induce acute disease and plasma virus loads were reduced by 2.5 to 4.0 logs at 15 days post-infection. The S2 deleted virus failed to produce any detectable clinical signs during a 5-month observation period. These results demonstrate that S2 gene expression is essential for disease expression of EIAV.
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Affiliation(s)
- Angela J Fagerness
- Department of Public Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606-8401, USA.
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Lim WS, Payne SL, Edwards JF, Kim I, Ball JM. Differential effects of virulent and avirulent equine infectious anemia virus on macrophage cytokine expression. Virology 2005; 332:295-306. [PMID: 15661161 DOI: 10.1016/j.virol.2004.11.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 09/08/2004] [Accepted: 11/19/2004] [Indexed: 11/21/2022]
Abstract
Equine infectious anemia virus (EIAV) causes rapid development of acute disease followed by recurring episodes of fever, thrombocytopenia, and viremia. Most infected equid eventually bring the virus under immunological control. We recently reported the development of an equine-specific ribonuclease protection assay (RPA) to quantitate mRNA levels of 10 cytokines. Using this newly developed RPA, we now show significant differences in cytokine induction in equine monocyte-derived macrophages (EMDM) exposed to virulent and avirulent EIAV. Virulent EIAV17 induced significant increases in interleukin (IL)-1alpha, IL-1beta, IL-6, IL-10, and tumor necrosis factor (TNF)-alpha by 0.5-1 h postinfection (hpi). In contrast, the avirulent virus failed to induce any of the tested cytokines above that of control levels. These data show a direct correlation between cytokine dysregulation and EIAV pathogenesis.
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Affiliation(s)
- W-S Lim
- Department of Pathobiology, College of Veterinery Medicine, Texas A and M University, 4467 TAMU, TVMC, College Station, TX 77843-4467, USA
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Ball JM, Swaggerty CL, Pei X, Lim WS, Xu X, Cox VC, Payne SL. SU proteins from virulent and avirulent EIAV demonstrate distinct biological properties. Virology 2005; 333:132-44. [PMID: 15708599 DOI: 10.1016/j.virol.2004.12.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Revised: 10/11/2004] [Accepted: 12/17/2004] [Indexed: 10/25/2022]
Abstract
Biologic activity of equine infectious anemia virus (EIAV) surface (SU) glycoprotein was assayed in a mouse model. Recombinant SU from virulent EIAV17 (SU17), administered intraperitoneally to mouse pups, induced dose-dependent diarrheal responses similar to those reported for SIV SU (Virology 277 (2000) 250). SU17 caused fluid accumulation without histological lesions in mouse intestinal loops, induced chloride secretory currents in Ussing chambers and increased inositol 1,4,5 triphosphate (IP3) levels in HT29 cells. An SU17 peptide, SU17(299-330), provoked a dose-dependent diarrheal response akin to enterotoxic peptides from SIV. In contrast, SU from an avirulent EIAV strain failed to induce a dose response in mouse pups and produced lower levels of activity than SU17 in Ussing chambers and IP3 assays. These results demonstrate that a mouse pup model is useful to monitor EIAV SU biologic activity, showing clear differences between the activities of SU derived from virulent and avirulent viruses, and may provide a useful screen of EIAV virulence.
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Affiliation(s)
- J M Ball
- Department of Pathobiology, Texas A&M University, Texas Veterinary Medical Center, MS4467, College Station, TX 77843, USA
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Gould SJ, Hildreth JEK, Booth AM. The Evolution of Alloimmunity and the Genesis of Adaptive Immunity. QUARTERLY REVIEW OF BIOLOGY 2004; 79:359-82. [PMID: 15669770 DOI: 10.1086/426088] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Infectious agents select for host immune responses that destroy infectious nonself yet maintain tolerance to self. Here we propose that retroviruses and other host-antigen associated pathogens (HAAPs) select for the genetic, biochemical, and cell biological properties of alloimmunity, also known as the histocompatibility or tissue rejection response. This hypothesis predicts the major observations regarding histocompatibility responses, including: (i) their existence in animals as diverse as sponges and humans; (ii) extreme polymorphism and balanced allele frequencies at histocompatibility loci, including the human MHC and blood group loci; (iii) the frequency dependent selection of histocompatibility alleles; (iv) the ancient age of many alloantigenic polymorphisms; (v) the high ratio of nonsynonymous mutations to synonymous mutations at histocompatibility loci; (vi) disassortative mating based on MHC alleles; (vii) the inability to explain the existence and continuing selection of histocompatibility alleles by other more conventional biochemical and genetic paradigms; and (viii) the susceptibility of HAAPs, particularly retroviruses such as HIV (human immunodeficiency virus), to histocompatibility reactions. In addition, the hypothesis that HAAPs select the forms and molecules of alloimmunity offers simple explanations for the evolution of histocompatibility systems over time, the initial selection of hypervariable immune mechanisms, and the genesis of adaptive immunity.
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Affiliation(s)
- Stephen J Gould
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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Payne SL, Pei XF, Jia B, Fagerness A, Fuller FJ. Influence of long terminal repeat and env on the virulence phenotype of equine infectious anemia virus. J Virol 2004; 78:2478-85. [PMID: 14963146 PMCID: PMC369206 DOI: 10.1128/jvi.78.5.2478-2485.2004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The molecular clones pSPeiav19 and p19/wenv17 of equine infectious anemia virus (EIAV) differ in env and long terminal repeats (LTRs) and produce viruses (EIAV(19) and EIAV(17), respectively) of dramatically different virulence phenotypes. These constructs were used to generate a series of chimeric clones to test the individual contributions of LTR, surface (SU), and transmembrane (TM)/Rev regions to the disease potential of the highly virulent EIAV(17). The LTRs of EIAV(19) and EIAV(17) differ by 16 nucleotides in the transcriptional enhancer region. The two viruses differ by 30 amino acids in SU, by 17 amino acids in TM, and by 8 amino acids in Rev. Results from in vivo infections with chimeric clones indicate that both LTR and env of EIAV(17) are required for the development of severe acute disease. In the context of the EIAV(17) LTR, SU appears to have a greater impact on virulence than does TM. EIAV(17SU), containing only the TM/Rev region from the avirulent parent, induced acute disease in two animals, while a similar infectious dose of EIAV(17TM) (which derives SU from the avirulent parent) did not. Neither EIAV(17SU) nor EIAV(17TM) produced lethal disease when administered at infectious doses that were 6- to 30-fold higher than a lethal dose of the parental EIAV(17). All chimeric clones replicated in primary equine monocyte-derived macrophages, and there was no apparent correlation between macrophage tropism and virulence phenotype.
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Affiliation(s)
- Susan L Payne
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas 77843-4467, USA.
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Abstract
A novel strain of equine infectious anemia virus (EIAV) called vMA-1c that rapidly and specifically killed infected equine fibroblasts (ED cells) but not other infectible cell lines was established. This strain was generated from an avirulent, noncytopathic strain of EIAV, MA-1. Studies with this new cytolytic strain of virus have permitted us to define viral parameters associated with EIAV-induced cell killing and begin to explore the mechanism. vMA-1c infection resulted in induction of rapid cell death, enhanced fusogenic activity, and increased rates of spread in equine fibroblasts compared to other strains of EIAV. The highly cytolytic nature of vMA-1c suggested that this strain might be superinfecting equine fibroblasts. Receptor interference studies demonstrated that prior infection of equine fibroblasts with EIAV did not alter the ability of vMA-1c to infect and kill these cells. In similar studies in a canine fibroblast cell line, receptor interference did occur. vMA-1c infection of equine fibroblasts was also associated with large quantities of unintegrated viral DNA, a well-established hallmark of retroviral superinfection. Cloning of the vMA-1c genome identified nucleotide changes that would result in at least one amino acid change in all viral proteins. A chimeric infectious molecular clone containing the vMA-1c tat, S2, and env open reading frames recapitulated most of the characteristics of vMA-1c, including superinfection, fibroblast killing, and fusogenic activity. In summary, in vitro selection for a strain of EIAV that rapidly killed cells resulted in the generation of a virus that was able to superinfect these cells, presumably by the use of a novel mechanism of cell entry. This phenotype mapped to the 3' half of the genome.
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Affiliation(s)
- Wendy Maury
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA.
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Cook RF, Cook SJ, Li FL, Montelaro RC, Issel CJ. Development of a multiplex real-time reverse transcriptase-polymerase chain reaction for equine infectious anemia virus (EIAV). J Virol Methods 2002; 105:171-9. [PMID: 12176154 DOI: 10.1016/s0166-0934(02)00101-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A single-tube reverse transcriptase-polymerase chain reaction (RT-PCR) using a fluorogenic real-time PCR detection method is described for the quantitation of equine infectious anemia virus (EIAV) RNA in the plasma of equids. To compensate for variations inherent in sample preparation a multiplex real-time RT-PCR system was developed that permitted the simultaneous calculation of the nucleic acid recovery rate along with the copy number of viral RNA molecules. Detection of EIAV RNA was linear from 10(9) to 10(1) molecules with intra- and inter-assay variability of less than 1% at 10(8), 10(6), 10(4) and 10(2) molecules.
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Affiliation(s)
- R Frank Cook
- Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546-0099, USA.
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Hines R, Maury W. DH82 cells: a macrophage cell line for the replication and study of equine infectious anemia virus. J Virol Methods 2001; 95:47-56. [PMID: 11377712 DOI: 10.1016/s0166-0934(01)00288-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In vivo, tissue macrophages have been implicated as an important cell for the replication of equine infectious anemia virus (EIAV). Laboratory investigations of EIAV/macrophage interactions, however, have been hampered by the laborious blood monocyte isolation procedures. In addition, adherent equine macrophage cultures generally have poor long-term viability and are resistant to transfection. This report describes an adherent canine macrophage-like cell line, DH82, that supports the replication of EIAV. This cell line was easily transfectable and supported EIAV Tat transactivation of the LTR. Electrophoretic mobility shift assays were carried out to determine which transcription factor binding sites within the LTR enhancer region were bound by DH82 nuclear extracts. It was found that five different motifs were occupied. The ets motifs that are bound by PU.1 in primary macrophage nuclear extracts specifically interacted with DH82 nuclear extracts. In addition, the PEA-2, Lvb and Oct motifs that are occupied by fibroblast nuclear extracts were also bound by DH82 nuclear extracts. Finally, the methylation-dependent binding protein (MDBP) site that is bound by all nuclear extracts investigated to date demonstrated specific interactions with DH82 nuclear extracts. The observation that both macrophage-specific and fibroblast-specific motifs were utilized by DH82 nuclear extracts suggested that both macrophage-adapted and fibroblast-adapted EIAV could replicate in DH82 cells. Indeed, infectivity studies demonstrated that strains of virus that exclusively replicate in macrophages can replicate in DH82 cells and fibroblast-adapted strains of virus can also replicate in these cells. Finally, these cells could be transfected readily with the EIAV molecular clone, pSPeiav19-2, and virus spread was detected within the culture. In conclusion, this study has identified a useful cell line that should facilitate the study of EIAV expression and replication.
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Affiliation(s)
- R Hines
- University of South Dakota, Lee Medical Building, 414 E Clark St., Vermillion, SD 57069, USA
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Abstract
Equine infectious anemia virus (EIAV) is an ungulate lentivirus that is related to human immunodeficiency virus (HIV). Much of the understanding of lentiviral gene regulation comes from studies using HIV. HIV studies have provided insights into molecular regulation of EIAV expression; however, much of the regulation of EIAV expression stands in stark contrast to that of HIV. This review provides an overview of the current state of knowledge of EIAV regulation by comparing and contrasting EIAV gene regulation to HIV. The role of EIAV gene regulation is discussed in relation to EIAV pathogenesis.
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Affiliation(s)
- W Maury
- Department of Microbiology, University of South Dakota School of Medicine, Vermillion 57069, USA.
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Maury W, Bradley S, Wright B, Hines R. Cell specificity of the transcription-factor repertoire used by a lentivirus: motifs important for expression of equine infectious anemia virus in nonmonocytic cells. Virology 2000; 267:267-78. [PMID: 10662622 DOI: 10.1006/viro.1999.0144] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The equine infectious anemia virus (EIAV) long-terminal repeat (LTR) has been identified as highly variable, both in infected horses and in cell culture. This nucleotide hypervariation is localized to the LTR enhancer region. The EIAV LTR has been implicated in controlling both the cell tropism and virulence of the virus and it is postulated that the enhancer-region hypervariation may be responsible for the LTR effects. Our previous studies have demonstrated that the presence of DNA motifs bound by the ets transcription-factor family member PU.1 are critically important for EIAV expression in equine macrophages. Here we identify and characterize the EIAV LTR enhancer motifs PEA-2, Lvb, Oct, and CRE, that bind to fibroblast nuclear extracts. Three of these four motifs, PEA-2, Oct, and CRE, were determined to be important for expression of the LTR in a fibroblast cell line that supports productive infection of EIAV. These motifs that are important for expression of the LTR in fibroblasts were found to be interdigitated between the PU.1 sites. We hypothesize that the combination of motif interdigitation and cell-specific usage of these motifs may be responsible for the observed EIAV LTR enhancer-region hypervariation.
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MESH Headings
- Animals
- Base Sequence
- Binding Sites
- Cell Line
- Chloramphenicol O-Acetyltransferase/genetics
- Chloramphenicol O-Acetyltransferase/metabolism
- DNA, Viral/chemistry
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Enhancer Elements, Genetic
- Fibroblasts/cytology
- Fibroblasts/metabolism
- Gene Expression Regulation, Viral
- Horses
- Infectious Anemia Virus, Equine/chemistry
- Infectious Anemia Virus, Equine/genetics
- Infectious Anemia Virus, Equine/metabolism
- Molecular Sequence Data
- Mutation
- Nuclear Proteins/metabolism
- Protein Binding
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Repetitive Sequences, Nucleic Acid/genetics
- Sequence Homology, Nucleic Acid
- Transcription Factors/metabolism
- Transcription, Genetic
- Transcriptional Activation
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Affiliation(s)
- W Maury
- Division of Basic Biomedical Sciences, University of South Dakota, Vermillion, South Dakota 57069, USA.
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Zheng YH, Sentsui H, Sugita M, Nakaya T, Kishi M, Hagiwara K, Inoshima Y, Ishihara C, Kono Y, Lu JL, Ikuta K. Replication ability in vitro and in vivo of equine infectious anemia virus avirulent Japanese strain. Virology 2000; 266:129-39. [PMID: 10612667 DOI: 10.1006/viro.1999.0076] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An attenuated equine infectious anemia virus (EIAV), V26, was previously prepared by 50 passages of the Japanese virulent strain V70 in primary horse macrophage culture. The horses inoculated with this V26 virus were shown to raise neutralizing antibodies against V70 without any viremia. Here, we investigated the in vitro and in vivo replication ability of V26. Comparison of the long-terminal repeat (LTR) sequences between V26 and V70 revealed a large insertion within the LTR U3 hypervariable region of V26. V26 with the mutation in the LTR showed much higher promoter activity in vitro than V70. This is consistent with the much higher replication rate of V26 in horse primary macrophage cultures compared with V70. In sharp contrast, we failed to identify the V26-specific LTR sequence by PCR, at least in sequential samples of plasma or peripheral blood mononuclear cells derived from three horses until day 62 after V26 inoculation. In contrast, antibody responses to EIAV were observed in all horses. The results suggest that the replication ability of V26 in vivo is extremely low. When one of the horses was subsequently challenged with cell-associated V70, it was found that the horse became PCR positive for EIAV. There was no LTR mutation in EIAV genome in samples periodically prepared from the V70-challenged horse. Thus it was suggested that the LTR mutation in EIAV, which occurs during serial passage in vitro, affects EIAV replication in vitro and in vivo.
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Affiliation(s)
- Y H Zheng
- Institute of Immunological Science, Hokkaido University, Sapporo, Kita-ku, Japan
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21
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Russell KE, Perkins PC, Hoffman MR, Miller RT, Walker KM, Fuller FJ, Sellon DC. Platelets from thrombocytopenic ponies acutely infected with equine infectious anemia virus are activated in vivo and hypofunctional. Virology 1999; 259:7-19. [PMID: 10364485 DOI: 10.1006/viro.1999.9737] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Thrombocytopenia is a consistent finding and one of the earliest hematological abnormalities in horses acutely infected with equine infectious anemia virus (EIAV), a lentivirus closely related to human immunodeficiency virus. Multifactorial mechanisms, including immune-mediated platelet destruction and impaired platelet production, are implicated in the pathogenesis of EIAV-associated thrombocytopenia. This study was undertaken to investigate whether regenerative thrombopoiesis and platelet destruction occurred in ponies acutely infected with EIAV. Circulating large, immature platelets were increased in ponies acutely infected with EIAV late in the infection when platelet count was at a nadir. Morphometric analysis of bone marrow from acutely infected ponies revealed significant increased in megakaryocyte area and megakaryocyte nuclear area. A trend toward increased numbers of megakaryocytes was also observed. Platelets from acutely infected ponies had increased surface-bound fibrinogen and ultrastructural changes consistent with in vivo platelet activation. Platelets also had hypofunctional aggregation responses to three agonists in vitro. We conclude that thrombocytopenia in ponies acutely infected with EIAV is regenerative and suggest that bone marrow platelet production is not severely compromised in these ponies. Our findings reveal that in vivo platelet activation occurs in ponies acutely infected with EIAV, and as a result platelets are hypofunctional in vitro. Activation of platelets in vivo may cause platelet degranulation or formation of platelet aggregates, which would result in removal of these damages platelets from circulation. This may represent a form of nonimmune-mediated platelet destruction in ponies acutely infected with EIAV.
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Affiliation(s)
- K E Russell
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA
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