Histopathological changes in simian immunodeficiency virus infection.

Area of Science:

• Veterinary Pathology
• Primate Immunology
• Infectious Diseases

Background:

• Simian immunodeficiency virus (SIV) is a lentivirus that infects non-human primates.
• SIV infection in rhesus and cynomolgus monkeys serves as a model for studying human immunodeficiency virus (HIV) pathogenesis.
• Understanding SIV-induced pathology is crucial for developing effective interventions.

Purpose of the Study:

• To characterize the histological lesions associated with SIV infection in rhesus and cynomolgus monkeys.
• To investigate the temporal progression of SIV-related pathology over 18 months.
• To identify potential mechanisms of SIV transmission and pathogenesis.

Main Methods:

• Histopathological examination of tissues from SIV-infected rhesus and cynomolgus monkeys.
• Analysis of lymphoreticular tissues, mucosa-associated lymphoid tissue, and central nervous system.
• Assessment of opportunistic infections and specific tissue transformations.

Main Results:

• Observed lymphoreticular changes include hyperplasia, follicular involution/depletion, and splenic amyloidosis.
• Hyperplasia in mucosa-associated lymphoid tissue and vaginal mucosal infiltrations suggest potential sexual transmission routes.
• Common findings include enterocolitis, brown adipose tissue transformation, and central nervous system lesions (glial activity, lymphocytic infiltration).
• Opportunistic infections were limited, with two cases of Pneumocystis carinii pneumonia noted.
• One monkey developed a lymphoma in the lumbar spinal cord.

Conclusions:

• SIV infection induces a spectrum of histological lesions in macaques, affecting multiple organ systems.
• The observed lesions, particularly in the lymphoid tissues and CNS, highlight the systemic impact of SIV.
• Findings provide insights into SIV pathogenesis and potential transmission dynamics relevant to HIV research.