New Study Shows That HIV Patients Lose Smallpox Immunity Despite Having Been Vaccinated In The Past
Source: Thailand Medical News Jan 03, 2020 4 years, 10 months, 1 week, 3 days, 21 hours, 5 minutes ago
According to a new research published in the Journal of Infectious Diseases,
HIV patients lose
immunity to
smallpox even though they were
vaccinated against the disease as children and have had much of their
immune system restored with antiretroviral therapy.
Termed as
HIV-associated immune amnesia, the finding 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. The study 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.
Dr 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, led the study. Dr Slifka and his colleagues compared the 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 medical 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.
The researchers told
Thailand Medical News that 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 new 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.
Reference : Archana Thomas et al, Loss of Pre-Existing Immunological Memory among HIV Infected Women Despite Immune Reconstitution with Antiretroviral Thera
py, The Journal of Infectious Diseases (2019). DOI: 10.1093/infdis/jiz678
