Journal of virology2000;
74(7);
3112-3121; doi: 10.1128/jvi.74.7.3112-3121.2000
Tissue sites of persistent infection and active replication of equine infectious anemia virus during acute disease and asymptomatic infection in experimentally infected equids.
Abstract: Equine infectious anemia virus (EIAV) infection of horses is characterized by recurring cycles of disease and viremia that typically progress to an inapparent infection in which clinical symptoms are absent as host immune responses maintain control of virus replication indefinitely. The dynamics of EIAV viremia and its association with disease cycles have been well characterized, but there has been to date no comprehensive quantitative analyses of the specific tissue sites of EIAV infection and replication in experimentally infected equids during acute disease episodes and during asymptomatic infections in long-term inapparent carriers. To characterize the in vivo site(s) of viral infection and replication, we developed a quantitative competitive PCR assay capable of detecting 10 copies of viral DNA and a quantitative competitive reverse transcription-PCR assay with a sensitivity of about 30 copies of viral singly spliced mRNA. Animals were experimentally infected with one of two reference viruses: the animal-passaged field isolate designated EIAV(Wyo) and the virulent cell-adapted strain designated EIAV(PV). Tissues and blood cells were isolated during the initial acute disease or from asymptomatic animals and analyzed for viral DNA and RNA levels by the respective quantitative assays. The results of these experiments demonstrated that the appearance of clinical symptoms in experimentally infected equids coincided with rapid widespread seeding of viral infection and replication in a variety of tissues. During acute disease, the predominant cellular site of viral infection and replication was the spleen, which typically accounted for over 90% of the cellular viral burden. In asymptomatic animals, viral DNA and RNA persisted in virtually all tissues tested, but at extremely low levels, a finding indicative of tight but incomplete immune control of EIAV replication. During all disease states, peripheral blood mononuclear cells (PBMC) were found to harbor less than 1% of the cellular viral burden. These quantitative studies demonstrate that tissues, rather than PBMC, constitute the predominant sites of virus replication during acute disease in infected equids and serve as resilient reservoirs of virus infection, even in the presence of highly effective immune responses that maintain a stringent control of virus replication in long-term inapparent carriers. Thus, these observations with EIAV, a predominantly macrophage-tropic lentivirus, highlight the role of tissues in sequestering lentiviral infections from host immune surveillance.
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This study investigates the specific sites in horses’ bodies where the Equine infectious anemia virus (EIAV) thrives and replicates during both acute outbreaks and periods of asymptomatic infection. The researchers used advanced methods to detect and quantify the virus in various tissues and blood cells, identifying the spleen as the primary site of infection and replication during acute disease while virtually all tissues harbored low virus levels in asymptomatic animals.
Objective and Methodology
The primary aim of the research was to identify the explicit tissue sites of EIAV infection and replication as this was overlooked in prior research. The researchers sought clarity on these areas to understand the virus better and potentially develop targeted treatment methods.
Two distinct quantitative assays were established by the researchers for the study, a quantitative competitive PCR assay and a quantitative competitive reverse transcription-PCR assay. These assays were created to detect the presence and quantity of viral DNA and RNA.
The subjects of the experiment, equids (horses and alike), were infected with two different versions of the virus for the experiment, namely EIAV(Wyo) and EIAV(PV).
Various tissues and blood cells were then isolated from the animals during the periods of acute disease and asymptomatic illness. These samples were analyzed for viral DNA and RNA levels using the two quantitative assays developed.
Key Findings
During the phase of acute disease, the research found that the virus efficiently spread and replicated in various tissues. The spleen was identified as the most common site, accounting for over 90% of the viral burden in cells. This indicates that the spleen is a primary site for EIAV infection and replication during periods of acute disease.
In the case of asymptomatic animals, the researchers found that the virus’ DNA and RNA persisted in practically all examined tissues, though at extremely low levels, suggesting a strong but not entirely perfect immune control of EIAV replication.
The study emphasized that tissues serve as the dominant sites for virus replication during acute disease and seemingly resilient reservoirs of virus infection, even amidst highly effective immune responses. In contrast, the role of peripheral blood mononuclear cells (PBMCs) in harboring the virus was determined to be minimal, accounting for less than 1% of the cellular viral burden.
Conclusion and Implications
The research, therefore, deduced that, similar to other lentiviruses that primarily target macrophages, EIAV uses tissues to hide from the host’s immune responses. This highlights the significant role tissues play in sustaining lentiviral infections despite the host’s robust immune reaction.
The evidence generated through this study can potentially guide future efforts towards the development of more targeted treatment strategies for EIAV. By understanding where the virus hides and thrives in the host body, scientists and clinicians can develop methods to specifically target these areas, enhancing the effectiveness of treatment options.
Cite This Article
APA
Harrold SM, Cook SJ, Cook RF, Rushlow KE, Issel CJ, Montelaro RC.
(2000).
Tissue sites of persistent infection and active replication of equine infectious anemia virus during acute disease and asymptomatic infection in experimentally infected equids.
J Virol, 74(7), 3112-3121.
https://doi.org/10.1128/jvi.74.7.3112-3121.2000
Department of Molecular Genetics and Biochemistry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Cook, S J
Cook, R F
Rushlow, K E
Issel, C J
Montelaro, R C
MeSH Terms
Animals
Base Sequence
DNA Primers
DNA, Viral / analysis
Equine Infectious Anemia / virology
Horses
Infectious Anemia Virus, Equine / genetics
Infectious Anemia Virus, Equine / physiology
RNA Splicing
RNA, Viral / analysis
RNA, Viral / genetics
Reverse Transcriptase Polymerase Chain Reaction
Virus Replication
Grant Funding
R01 CA049296 / NCI NIH HHS
T32 AI007487 / NIAID NIH HHS
R01 CA49296 / NCI NIH HHS
5T32 AI07487 / NIAID NIH HHS
P41 RR006009 / NCRR NIH HHS
2 P41 RR06009 / NCRR NIH HHS
References
This article includes 48 references
Bagnarelli P, Menzo S, Valenza A, Manzin A, Giacca M, Ancarani F, Scalise G, Varaldo PE, Clementi M. Molecular profile of human immunodeficiency virus type 1 infection in symptomless patients and in patients with AIDS.. J Virol 1992 Dec;66(12):7328-35.
Bagnarelli P, Valenza A, Menzo S, Sampaolesi R, Varaldo PE, Butini L, Montroni M, Perno CF, Aquaro S, Mathez D, Leibowitch J, Balotta C, Clementi M. Dynamics and modulation of human immunodeficiency virus type 1 transcripts in vitro and in vivo.. J Virol 1996 Nov;70(11):7603-13.
Chong YH, Payne SL, Issel CJ, Montelaro RC, Rushlow KE. Characterization of the antigenic domains of the major core protein (p26) of equine infectious anemia virus.. J Virol 1991 Feb;65(2):1007-12.
Cunningham TP, Montelaro RC, Rushlow KE. Lentivirus envelope sequences and proviral genomes are stabilized in Escherichia coli when cloned in low-copy-number plasmid vectors.. Gene 1993 Feb 14;124(1):93-8.
Embretson J, Zupancic M, Ribas JL, Burke A, Racz P, Tenner-Racz K, Haase AT. Massive covert infection of helper T lymphocytes and macrophages by HIV during the incubation period of AIDS.. Nature 1993 Mar 25;362(6418):359-62.
Gendelman HE, Narayan O, Kennedy-Stoskopf S, Kennedy PG, Ghotbi Z, Clements JE, Stanley J, Pezeshkpour G. Tropism of sheep lentiviruses for monocytes: susceptibility to infection and virus gene expression increase during maturation of monocytes to macrophages.. J Virol 1986 Apr;58(1):67-74.
Gendelman HE, Narayan O, Molineaux S, Clements JE, Ghotbi Z. Slow, persistent replication of lentiviruses: role of tissue macrophages and macrophage precursors in bone marrow.. Proc Natl Acad Sci U S A 1985 Oct;82(20):7086-90.
Lifson JD, Nowak MA, Goldstein S, Rossio JL, Kinter A, Vasquez G, Wiltrout TA, Brown C, Schneider D, Wahl L, Lloyd AL, Williams J, Elkins WR, Fauci AS, Hirsch VM. The extent of early viral replication is a critical determinant of the natural history of simian immunodeficiency virus infection.. J Virol 1997 Dec;71(12):9508-14.
Michael NL, Vahey M, Burke DS, Redfield RR. Viral DNA and mRNA expression correlate with the stage of human immunodeficiency virus (HIV) type 1 infection in humans: evidence for viral replication in all stages of HIV disease.. J Virol 1992 Jan;66(1):310-6.
Pantaleo G, Graziosi C, Demarest JF, Butini L, Montroni M, Fox CH, Orenstein JM, Kotler DP, Fauci AS. HIV infection is active and progressive in lymphoid tissue during the clinically latent stage of disease.. Nature 1993 Mar 25;362(6418):355-8.
Piatak M Jr, Saag MS, Yang LC, Clark SJ, Kappes JC, Luk KC, Hahn BH, Shaw GM, Lifson JD. High levels of HIV-1 in plasma during all stages of infection determined by competitive PCR.. Science 1993 Mar 19;259(5102):1749-54.
Saltarelli MJ, Hadziyannis E, Hart CE, Harrison JV, Felber BK, Spira TJ, Pavlakis GN. Analysis of human immunodeficiency virus type 1 mRNA splicing patterns during disease progression in peripheral blood mononuclear cells from infected individuals.. AIDS Res Hum Retroviruses 1996 Oct 10;12(15):1443-56.
Sambrook J, Fritsch E F, Maniatis T. Molecular cloning: a laboratory manual. 2nd ed. Cold Spring Harbor, N.Y: Cold Spring Harbor Laboratory Press; 1989.
Simmonds P, Balfe P, Peutherer JF, Ludlam CA, Bishop JO, Brown AJ. Human immunodeficiency virus-infected individuals contain provirus in small numbers of peripheral mononuclear cells and at low copy numbers.. J Virol 1990 Feb;64(2):864-72.
Du C, Ma J, Liu Q, Li YF, He XJ, Lin YZ, Wang XF, Meng QW, Wang X, Zhou JH. Mice transgenic for equine cyclin T1 and ELR1 are susceptible to equine infectious anemia virus infection. Retrovirology 2015 Apr 28;12:36.
Craigo JK, Ezzelarab C, Montelaro RC. Development of a high throughput, semi-automated, infectious center cell-based ELISA for equine infectious anemia virus. J Virol Methods 2012 Nov;185(2):221-7.
Cappelli K, Capomaccio S, Cook FR, Felicetti M, Marenzoni ML, Coppola G, Verini-Supplizi A, Coletti M, Passamonti F. Molecular detection, epidemiology, and genetic characterization of novel European field isolates of equine infectious anemia virus. J Clin Microbiol 2011 Jan;49(1):27-33.
Craigo JK, Barnes S, Cook SJ, Issel CJ, Montelaro RC. Divergence, not diversity of an attenuated equine lentivirus vaccine strain correlates with protection from disease. Vaccine 2010 Nov 29;28(51):8095-104.
Fraser DG, Mealey RH, McGuire TC. Selecting peptides to optimize Th1 responses to an equine lentivirus using HLA-DR binding motifs and defined HIV-1 Th peptides. Immunogenetics 2003 Oct;55(7):508-14.