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The genome and proteins of HIV (human immunodeficiency virus) have been the subject of extensive research since the discovery of the virus in 1983. [1] [2] "In the search for the causative agent, it was initially believed that the virus was a form of the Human T-cell leukemia virus (HTLV), which was known at the time to affect the human immune system and cause certain leukemias.
A reverse transcriptase (RT) is an enzyme used to convert RNA genome to DNA, a process termed reverse transcription.Reverse transcriptases are used by viruses such as HIV and hepatitis B to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, and by eukaryotic cells to extend the telomeres at the ends of their linear chromosomes.
Reverse transcription of the HIV genome into double-stranded DNA. Shortly after the viral capsid enters the cell, an enzyme called reverse transcriptase liberates the positive-sense single-stranded RNA genome from the attached viral proteins and copies it into a complementary DNA (cDNA) molecule. [69]
HIV is a retrovirus, which comprise a large and diverse family of RNA viruses that make a DNA copy of their RNA genome after infection of a host cell. An essential step in the replication cycle of HIV-1 and other retroviruses is the integration of this viral DNA into the host DNA.
Fusion: HIV replication cycle begins when HIV fuses with the surface of the host cell. The capsid containing the virus’s genome and proteins then enters the cells. Reverse transcription : The capsid ensures the secure transport of the viral genome and reverse-transcription machinery from the cytoplasm's periphery to transcriptionally active ...
Reverse transcriptase possesses [RNase H] activity for destruction of the RNA-template. Integrase binds both the viral cDNA generated by reverse transcriptase and the host DNA. It then processes the LTRs before inserting the viral genome into the host DNA. Tat acts as a trans-activator during transcription to enhance initiation and elongation.
Without Tat activity, HIV transcription is restricted and often results in abortive transcripts. [8] Tat activates the LTR through interactions with the elongation factor P-TEFb; [9] Tat binds to cyclin T1, which is a unit of P-TEFb. [9] [10] Tat:P-TEFb directs RNA polymerases to the provirus genome by binding the HIV transactivation response ...
Like other lentiviruses, HIV-1 encodes a trans-activating regulatory protein (Tat), which is essential for efficient transcription of the viral genome. [7] [8] Tat acts by binding to an RNA stem-loop structure, the trans-activation response element (TAR), found at the 5′ ends of nascent HIV-1 transcripts.