Allergy-Immunology Glossary

A retrovirus is any virus belonging to the viral family Retroviridae. The family Retroviridae comprises a variety of enveloped RNA viruses, such as endogenous retroviruses, leukemia viruses, and HIV-1, the replicative strategy of which includes as essential steps reverse transcription of the virion RNA into linear double-stranded DNA and the subsequent integration of this DNA into the genome of the cell[1]. It is a DNA polymerase that is able to make genetic transcriptase information flow in the reverse [RNA ->DNA] of its normal [RT] direction [DNA -> RNA][3], HIV-1 RT is responsible for the production of a double stranded DNA copy of the single stranded RNA genome that is contained in the HIV- 1 virus particle. HIV-1 RT is of tremendous medical interest as it is the target enzyme for the best known of anti-AIDS drugs, zidovudine, which acts by causing chain termination of the polymerase reaction[4]. CD4 [cluster of differentiation 4] is a glycoprotein expressed on the surface of T helper cells, regulatory T cells, monocytes, macrophages, and dendritic cells. CD4 is also a primary receptor used by HIV-1 to gain entry into host T cells. The CD4 gene is on chromosome 12. CD4 functions to initiate or augment the early phase of T-cell activation[5. Human CD4 may function as an important mediator of indirect neuronal damage in infectious and immune-mediated diseases of the central nervous system[6]