Asymptomatic Infection of the Central Nervous System by the Macaque Immunosuppressive Type D Retrovirus, SRV-1

Abstract

SUMMARYThe aetiological agent of spontaneously occurring simian acquired immune deficiency syndrome (SAIDS) in rhesus monkeys (Macaca mulatta) at the California Primate Research Center is a type D retrovirus designated SAIDS retrovirus serotype 1 (SRV-1). SRV-1 DNA and RNA have previously been detected in the brains of rhesus monkeys with SAIDS in the absence of viral antigen or neuropathological lesions. In this study we further define the relationship between SRV-1 and the central nervous system (CNS) in rhesus monkeys by examining the CNS for infectious SRV-1, viral antigen and anti-SRV-1 antibodies. In addition, cerebrospinal fluid (CSF) was assayed for alterations in IgG and albumin levels, IgG/albumin ratios and cell count in comparison to uninfected control animals. No differences in CSF parameters were detected between infected and uninfected animals except for the presence of infectious SRV-1 which was isolated from the CSF from 13 out of 19 (68%) viraemic rhesus monkeys. The probable source of this virus was the choroid plexus, where approximately 1 in 1000 surface epithelial cells were found to contain viral antigen by immunohistochemistry. Antibodies against SRV-1 were not detected in the CSF even when present in the serum. Neither infectious virus nor viral antigen were found in the brain parenchyma of any animal examined. Thus infection of the CNS by SRV-1 appears to be subclinical without an intrathecal immune response. This may be related to the apparent restriction of productive infection in the CNS to cells of the choroid plexus.

Detection of SRV/D shedding in body fluids of cynomolgus macaques and comparison of partial gp70 sequences in SRV/D-T isolates

“…Using anti-SRV/D-1 gp20 monoclonal antibody (F2-1), virus specific signals were observed at the end portion of the ducts in salivary glands similar to that reported in rhesus macaques infected with SRV/D-1 ( Fig. 2A) [16]. When a newly developed nucleic acid hybridization technology (ISH-AT-CSA) [15] was applied to another section of the same salivary gland sample, similar SRV/D-T signals were observed in the duct (Fig.…”

Molecular Localization Techniques in the Diagnosis and Characterization of Nonhuman Primate Infectious Diseases

“…Type D simian retroviruses (SRVs) were once common in domestically bred rhesus macaques and the most frequent cause of acquired immunodeficiency in this species. 31,41–43,86 Affected animals were viremic but variably seropositive, often developing progressive wasting, diarrhea, and opportunistic infections. Clinically, the disease overlaps with the condition caused by natural or experimental infection of rhesus macaques with SIVmac, but it differs in several important respects.…”

REVIEW ARTICLE: An updated review of simianbetaretrovirus(SRV) in macaque hosts

“…Serial titration assays suggested that during natural infection, SRV is detected in only 1 in 750 to 1 in 25,000 circulating lymphocytes [6]. Immunohistochemistry, Southern blot studies, and electron microscopy have revealed the presence of the virus in epithelial cells of the gastrointestinal tract, mouth, salivary glands, and choroid plexus, as well as in lymphoid cells in lymph nodes, spleen, and thymus [40–43]. Interestingly, SRV‐1 nucleic acids, in the absence of detectable antigens or neuropathy, have been detected in the choroid plexus epithelial cells and spinal fluid, suggesting viral latency in the central nervous system [42].…”