HIV Virus Structure
The Human Immunodeficiency Virus (HIV) is a complex retrovirus with a unique structure that plays a crucial role in its ability to infect human cells and cause AIDS.
Genome and Proteins
HIV’s genome is composed of two strands of positive-sense single-stranded RNA (ssRNA). The complete sequence of the HIV-1 genome has been solved to single-nucleotide resolution. The genome encodes a small number of viral proteins, which establish cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries.
Viral Proteins
HIV is composed of 15 types of viral proteins. These proteins play essential roles during the HIV life cycle. They allow the virus to infect cells of the immune system and force them to build new copies of the virus.
Viral Structure
The HIV virion is approximately 100 nm in diameter. Its innermost region consists of a cone-shaped core that includes two copies of the ssRNA genome, the enzymes reverse transcriptase, integrase and protease, some minor proteins, and the major core protein. This core is enclosed by a capsid, which is further enclosed by a viral envelope and associated matrix.
Lipid Bilayer Membrane
urrounding the virus is a lipid bilayer membrane. This membrane contains a few proteins from the last host cell it infected. These proteins, along with the viral proteins, allow the virus to infect cells of the immune system and force them to build new copies of the virus.
Role of the RNA Genome
The two copies of RNA are often identical, yet they are not independent, but form a compact dimer within the virion. The dimeric nature of the RNA genome of the virus may play a structural role in viral replication. Having two copies of RNA would allow the reverse transcriptase to switch templates when encountering a break in the viral RNA, thus completing the reverse transcription without loss of genetic information.
Conclusion
The structure of HIV is a testament to its evolutionary success as a pathogen. Its unique structure allows it to effectively invade host cells and replicate, leading to the progression of AIDS in humans. Understanding the structure of HIV is crucial for the development of effective treatments and vaccines against this devastating virus.
