HIV-Associated Immune Amnesia Could Explain Why HIV-Positive People Have Shorter Lives

Immune amnesia could explain how people forget their immunity against illnesses
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A new study led by the Oregon Health & Science University School of Medicine and Oregon National Primate Research Center found Human Immunodeficiency (HIV) patients lose immunity to smallpox, even though they were vaccinated against the disease as children.

Called HIV-associated immune amnesia, this finding published on January 2, 2020, could explain why people living with HIV still tend to have shorter lives on average than their HIV-negative counterparts, despite being on antiretroviral therapy. 

This new study was published in the Journal of Infectious Diseases and follows other research recently published in the journals Science and Science Immunology that found the immune systems of children who contracted measles similarly "forgot" their immunity against other illnesses, such as influenza.

The previous study was published on October 31, 2019, found measles infections in children can eliminate the immune system’s memory to fight off other illnesses.

That was the first study to show definitive evidence that a measles virus infection can destroy important immune cells that ‘remember’ previous encounters with specific bacteria.

Led by Mark K. Slifka, Ph.D., a professor of molecular microbiology and immunology at the Oregon Health & Science University School of Medicine and Oregon National Primate Research Center, this new study compared T-cell and antibody responses of a total of 100 HIV-positive and HIV-negative women who were vaccinated against smallpox in their youth.

The research team chose smallpox because its last known U.S. case was in 1949, meaning study subjects haven't recently been exposed to its virus, which would have triggered new T-cell and antibody responses.

They found the immune systems of HIV-positive women who were on antiretroviral therapy had a limited response when their blood was exposed to the vaccina virus, which is used in the smallpox vaccine. 

Normally, those vaccinated against smallpox have CD4 T cells that remember the virus and respond in large numbers when they're exposed again. Previous research has shown smallpox virus-specific CD4 T cells are maintained for up to 75 years after vaccination.

This finding happened despite the fact that antiretroviral therapy works by boosting CD4 T cell counts in HIV-positive patients. This indicates that while antiretroviral therapy may boost total T cell counts overall, it can't recover virus-specific T cells generated from prior childhood vaccinations.

Dr. Slifka and his colleagues plan to evaluate whether the same phenomenon occurs in HIV-infected men and if people living with HIV also lose immune memory to other diseases.

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Researchers who contributed to this study are affiliated with OHSU, SUNY Downstate, Georgetown University, Cornell University, University of Southern California and John Hopkins University.

This research was supported by the National Institutes of Health Public Health Service (grant U19 AI109948) and the Oregon National Primate Research Center (grant 8P51 OD011092).

HIV vaccine news published by Precision Vaccinations.