Characterization of a retravirus isolated from squirrel monkeys

Area of Science:

• Virology
• Molecular Biology
• Primate Research

Background:

• Retroviruses are RNA viruses that replicate through a DNA intermediate.
• Squirrel monkeys (Saimiri sciureus) are New World monkeys with limited research on their associated retroviruses.
• Previous retroviral isolates from primates include Mason-Pfizer monkey virus and baboon endogenous virus.

Purpose of the Study:

• To characterize a newly isolated retrovirus from squirrel monkeys.
• To determine if the new isolate is antigenically related to known retroviruses.
• To establish the unique characteristics of this novel retrovirus.

Main Methods:

• Isolation and propagation of the retrovirus in various cell lines (human, mink, canine).
• Biochemical characterization including reverse transcriptase activity, buoyant density, and polypeptide analysis using SDS-PAGE.
• Glycoprotein identification via [3H]glucosamine labeling.
• Antigenic cross-reactivity assays using species- and interspecies-specific tests.

Main Results:

• The new retrovirus, SMRV, exhibits Mg2+-dependent reverse transcriptase activity and specific buoyant densities.
• SDS-PAGE revealed a distinct polypeptide pattern for SMRV compared to other known retroviruses, with major polypeptides at 40,000, 20,000, 14,000, and 8,000 daltons.
• A major viral glycoprotein (gp73) was identified in infected human rhabdomyosarcoma cells.
• SMRV showed no antigenic relatedness to a panel of 10 other retroviruses, including Mason-Pfizer monkey virus and mouse mammary tumor virus.

Conclusions:

• Squirrel monkey retrovirus (SMRV) represents a new genus of retrovirus.
• SMRV is the first retroviral isolate identified from a New World monkey.
• The distinct biochemical and antigenic properties of SMRV highlight its novelty.