HIV: a new risk factor
Scientists have uncovered an unusual connection between the microflora of the penis and HIV
Virologists have uncovered an unusually strong connection between the microflora of the genitals and the immunodeficiency virus by discovering several strains of bacteria that increase the likelihood of HIV infection by 53-64%, according to an article published in the journal mBio (Liu et al., Penile Anaerobic Dysbiosis as a Risk Factor for HIV Infection).
"For the first time, we were able to find out that the microflora of the penis can influence how often men become infected with HIV. The more oxygen–intolerant bacteria were contained in the microflora of the genitals, the higher the risk of infection," says Cindy Liu from George Washington University (in a press release Study Points to Penile Microbiome as a Risk Factor for HIV in Men - VM).
Despite popular ideas in society about the super-contagious nature of HIV, sexual contact with a sick person quite rarely, in less than 1% of cases, leads to its penetration into the body and successful rooting of the immunodeficiency virus in the T-cells of its new victim. As scientists have found out in recent years, the probability of infection is influenced by many factors related to both the virus itself and the peculiarities of the human body.
For example, a few years ago, biologists discovered, observing the spread of the AIDS epidemic in Africa, that circumcision significantly reduces the likelihood of HIV infection, and the degree of risk reduction strongly depended on which type of virus was widespread in the region. In addition, the presence of certain mutations in genes associated with the work of immune cells can make a person "invulnerable" to infection, or almost not susceptible to it.
Liu and her colleagues discovered another factor affecting sexual transmission of HIV by observing the health of several hundred heterosexual men living in Uganda and actively changing their sexual partners. During two years of observation, 46 of them became infected with HIV, which allowed scientists to comprehensively study what factors could contribute to the successful rooting of the infection.
During these observations, scientists collected, in addition to blood samples and other tissues, samples of the microflora of the penis and studied its species composition. When virologists began to summarize the results of this monitoring, they noticed that the infected men had a fundamentally different microflora compared to other participants in the program.
In particular, ten times more bacteria belonging to four genera – Prevotella, Dialister, Finegoldia and Peptoniphilus - were present in their genitals. The presence of all four microbes increased the likelihood of HIV infection by 64%, and the presence of a combination of several of these bacteria increased the chances of catching the virus by about 53%.
While scientists do not know exactly how microbes are associated with HIV, however, they suggest that all these bacteria, leading an anaerobic lifestyle, can interact in a special way with immune cells that the virus infects, "luring" them to the surface of the mucous membrane and helping the virus to come into contact with them.
"Immune cells are the gateway to HIV, and our experiments show that some bacteria can produce specific biochemical alarms, such as interleukin-8, which cause these cells to accumulate in the penis, increasing the likelihood of their infection with HIV. In the case of other diseases, similar actions by microbes would be useful, but this only makes the task easier for the virus," explains Lance Price, a colleague of Liu.
In any case, this fact, as scientists note, can be used to deter and combat HIV in the most vulnerable regions of the world, giving people drugs that destroy these microbes and reduce the chances of infection.
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26.07.2017