HIV Microbiological Characteristics
HIV is a single-stranded RNA retrovirus that uses reverse transcriptase to convert its RNA genome into double-stranded DNA, which then integrates into the host cell's nucleus.
Viral Structure and Classification
HIV is definitively classified as a retrovirus with the following key microbiological features:
- Single-stranded RNA genome: HIV carries two copies of positive-sense single-stranded RNA as its genetic material 1, 2
- Reverse transcriptase enzyme: The virus encodes reverse transcriptase (RT), which performs both RNA-dependent and DNA-dependent DNA synthesis to convert the viral RNA genome into double-stranded DNA 1, 2
- DNA integration: The newly synthesized double-stranded viral DNA is stably integrated into the host cell's chromosomal DNA, establishing the provirus 3, 1, 2
Replication Mechanism
The HIV replication cycle follows a distinct retroviral pattern:
- Reverse transcription process: Following cell entry, the single-stranded RNA genome undergoes reverse transcription by the viral RT enzyme, producing double-stranded DNA 4, 1, 5
- RT enzyme structure: HIV-1 RT consists of a heterodimer with two subunits (p66 and p51), with the p66 subunit containing both the reverse transcriptase and RNase H domains 1
- Integration and persistence: The double-stranded DNA integrates into host chromosomes and serves as the template for producing new viral generations 1, 2
- Proviral DNA characteristics: Once integrated, the proviral DNA can remain latent in quiescent cells or become transcriptionally active, producing viral RNA, proteins, and virions 3
Critical Distinction
HIV is NOT a double-stranded RNA virus and does NOT use RNA-dependent RNA polymerase. Instead, it uses reverse transcriptase (an RNA-dependent DNA polymerase) to synthesize DNA from its RNA template 1, 2. This fundamental characteristic distinguishes retroviruses from other RNA viruses and makes reverse transcriptase the primary target for antiretroviral therapy such as AZT and other nucleoside analogues 6, 2.