Molecular Pathogens 2024, Vol.15, No.1, 9-16 http://microbescipublisher.com/index.php/mp 11 reduced drug sensitivity, leading to drug resistance. 2.2 Cause and mechanism of virus mutation The reasons and mechanisms of HIV mutation include the high error rate of reverse transcriptase, rapid reproduction and replication, as well as selection pressure and cross-infection. Reverse transcriptase is a key enzyme in the replication process of HIV, responsible for converting the virus's RNA into DNA. However, reverse transcriptase has a high error rate, which means mutations can occur during each replication process. These mutations can lead to errors or deletions in the genome, thereby affecting the survival and replication of the virus. HIV has the ability to rapidly reproduce and replicate, producing billions of virus particles every day. During this rapid replication process, viruses often experience replication errors. The accumulation of these errors due to the large number of viruses leads to frequent mutations. These mutations can be point mutations (changes in a single base pair), insertions or deletions (insertion or deletion of DNA fragments), or gene recombination (exchange of genes between different HIV strains). Selection pressure and cross-infection are also important factors in HIV mutation. The attack by the host immune system on the virus creates selection pressure, selecting for those mutant strains that can evade immune responses. These mutant strains gradually become dominant in the population, ultimately leading to immune escape. When different HIV strains infect the same host, their genomes can undergo recombination, forming new mutant virus strains. These mutations and variations make HIV complex and diverse, with the ability to evade the immune system and antiviral drugs. This poses a significant challenge to the treatment and prevention of the disease, and requires research and efforts to find effective strategies to combat HIV. 2.3 The impact of mutations on viruses Mutations have various impacts on HIV. Mutations make HIV highly variable, which means there is a large genetic difference between virus strains. This variability poses difficulties for antiviral treatment and vaccine development, as a specific drug or vaccine may be effective against one virus strain but not another. Mutations also lead to the development of drug resistance, rendering previously effective drugs ineffective. Mutations allow HIV to evade recognition and attack by the host immune system. Viral mutations can lead to changes in the structure of surface proteins (such as the HIV envelope protein gp120), enabling the virus to evade antibodies produced by the host. This antibody evasion mutation makes it difficult for the immune system to effectively fight the virus, increasing the severity and progression of the disease. Mutations can also affect the virulence and transmissibility of HIV. Some mutations may increase the infectiousness of the virus, making it more likely to spread through sexual or blood transmission to others. Mutations can also affect the replication rate and efficiency of the virus, thereby affecting its pathogenic potential and course of the disease. 3 Interaction between Host Antibody Response and AIDS Virus 3.1 Response mechanism of host immune system to AIDS virus infection The host immune system plays a crucial role in the response to HIV infection, and it employs multiple mechanisms to counteract the virus's attack. Firstly, the host immune system identifies and attacks cells infected with HIV. After infection, the virus releases some viral proteins that can be recognized as "foreign invaders" by immune system cells. The immune system tags these infected cells and destroys them through immune cells such as cytotoxic T cells (Mueller et al., 2018) (Figure 2). To combat HIV, the host immune system produces specific antibodies. After infection, the immune system activates B cells and prompts them to produce specific antibodies. These antibodies can recognize and bind to the surface proteins of the virus, thereby preventing further infection of host cells and prompting immune cells to clear the virus that is marked by antibodies. The host immune system can regulate and control immune responses
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