Reserve transcriptase sequence in HIV is best described as -
Reverse transcription is an error-prone process and multiple mutations arise with ongoing replication, which results in considerable viral genetic heterogeneity. Viral DNA is transpoed into the nucleus and integrated within the host cell genome by the integrase enzyme. Integrated virus is known as proviral DNA and persists for the life of the cell. Cells infected with proviral HIV DNA produce new virions only if they undergo cellular activation, resulting in the transcription of viral messenger RNA (mRNA) copies, which are then translated into viral peptide chains. The precursor polyproteins are then cleaved by the viral protease enzyme to form new viral structural proteins and enzymes that migrate to the cell surface and are assembled using the host cellular apparatus to produce infectious viral paicles; these bud from the cell surface, incorporating the host cell membrane into the viral envelope. The mature virion then infects other CD4 cells and the process is repeated. CD4 lymphocytes that are replicating HIV have a very sho survival time of about 1 day. It has been estimated that in asymptomatic HIV-infected people, more than 1010 virions are produced and 109 CD4 lymphocytes destroyed each day. The CD4 lymphocytes are destroyed primarily by the host immune response rather than by cytopathic effects of HIV. A small percentage of T-helper lymphocytes enter a post- integration latent phase. Latently infected cells are impoant as sanctuary sites from antiretroviral drugs, which act only on replicating virus. Current A is unable to eradicate HIV infection due to the persistence of proviral DNA in long-lived latent CD4 cells. Ref Harrison 20th edition pg 978
RNA-DNA-RNA
DNA-RNA
DNA-RNA-DNA
RNA-DNA
Infection