The strain of HIV transmitted from those who possess the genetic advantages to control the virus (non-progressors) appears to be attenuated and results in improved survival, even when the newly infected person does not have the non-progressor genes, according to a South African study published in PLoS Pathogens. Essentially, the finding indicates that the HIV virus is mutated to a less virulent form when it is passed-on by a non-progressor.
The researchers, from CAPRISA (the Centre for the AIDS Program of Research in South Africa), said that it was significant that the mutations to HIV which occur in a person with advantageous genes lead to a lower viral load. "Low viral load is a goal of several HIV vaccines as it means that these HIV infected people will be clinically well for longer and be less likely to spread the virus," said Professor Salim Abdool Karim, Director of CAPRISA.
Co-researcher Carolyn Williamson explained that HLA genes affect the rate of disease progression in HIV-infected individuals, alerting the immune system to HIV's presence. HIV can evade the immune system by mutating into forms unrecognizable by the HLA. However, it is known that some people (non-progressors) have versions of the HLA gene that can only be evaded by the virus if it mutates to a form that has a reduced replication rate.
The researchers identified two mutations that were associated with lower viral loads and higher CD4 counts post-infection. Both had been previously identified as immune evasion mutations that compromise viral replication capacity. This study indicates that even people who do not possess the beneficial genes and are infected by reproductively compromised viruses may have better survival prospects. "This study shows that genetic polymorphisms in the transmitted virus can offer survival advantage to a newly infected person," noted Williamson. The finding could profoundly influence our understanding of HIV and have implications for HIV vaccine design and immunotherapeutics, she concluded.
Read the full CAPRISA Paper
Natural Immunity Comes Under Spotlight In HIV Fight
Natural Gene Mutation Protects HIV-Infected Patients
Minor Mutations In HIV Virus Have Major Impact
Source: Public Library of Science