Humans and chimpanzees are the natural hosts for HIV. Non-human primate models of SIV/SHIV
infection in rhesus, cynomologus and pigtail macaques have been used extensively as excellent model systems for pathogenesis and
vaccine studies. However, owing to the variability of
disease progression in infected macaques, a phenomenon identical to humans, coupled with their prohibitive costs, there exists a critical need for the development of small-animal models in which to study the untoward effects of HIV-1
infection. Owing to the fact that rodents are not the natural permissive hosts for lentiviral
infection, development of small animal models for studying
virus infection has used strategies that circumvent the steps of viral entry and
infection. Such strategies involve overexpression of toxic
viral proteins, SCID mice engrafted with the human PBLs or macrophages, and EcoHIV chimeric virus wherein the gp120 of HIV-1 was replaced with the gp80 of the ecotropic murine leukemia virus. Additional strategy that is often used by investigators to study the toxic effect of
viral proteins involves direct stereotactic injection of the
viral protein(s) into specific brain regions. The present report is a compilation of the applications of direct administration of Tat into the striatum to mimic the effects of the viral
neurotoxin in the CNS. Added advantage of this model is that it is also amenable to repeated intraperitoneal
cocaine injections, thereby allowing the study of the additive/synergistic effects of both the
viral protein and
cocaine. Such a model system recapitulates aspects of HAND in the context of
drug abuse.