Previous Article | Next Article ![]()
Journal of Virology, April 2000, p. 3112-3121, Vol. 74, No. 7
Department of Molecular Genetics and
Biochemistry, School of Medicine, University of Pittsburgh,
Pittsburgh, Pennsylvania 15261,1 and
Gluck Equine Research Center, Department of Veterinary
Science, University of Kentucky, Lexington, Kentucky
405462
Received 9 August 1999/Accepted 20 December 1999
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
EIAVWyo and the virulent cell-adapted strain
designated EIAVPV. 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.
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Tissue Sites of Persistent Infection and Active Replication of
Equine Infectious Anemia Virus during Acute Disease and Asymptomatic
Infection in Experimentally Infected Equids

*
Corresponding author. Mailing address: Department of
Molecular Genetics and Biochemistry, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261. Phone: (412) 648-8869. Fax: (412)
383-8859. E-mail: rmont{at}pop.pitt.edu.
Present address: Ross Products Division, Abbott Laboratories,
Columbus, OH 43215.
This article has been cited by other articles:
| J. Bacteriol. | Mol. Cell. Biol. | Microbiol. Mol. Biol. Rev. |
|---|
| Clin. Vaccine Immunol. | ALL ASM JOURNALS |
|---|