Higher Immune Response in Female Mice Confers Better Protection Against Influenza

NIAID Now | November 19, 2018

A person’s sex has been shown to affect immune responses, including the response to both influenza virus infection and vaccination. Women have consistently stronger immune responses compared with men, including higher antibody responses to viruses like influenza, hepatitis B, herpes virus, and others.

To investigate whether the differential immune response in females confers greater protection, NIAID-funded researchers evaluated the differences between the immune response of male and female mice to influenza infection and vaccination. They found that the immune responses of female mice to infection and vaccination were greater than the responses of male mice. The researchers also observed that vaccinated females produced antibodies that were better at protecting against the 2009 H1N1 strain of influenza virus than antibodies from their male counterparts. This increased protection was due to the production of higher-quality antibodies against the H1N1 influenza virus, rather than to production of a larger quantity of antibodies, by the female mice.

The researchers next examined whether the higher-quality vaccine-induced antibodies in females were due to differences in expression of genes in B cells, a type of white blood cell that produces antibodies. They found that expression of the Tlr7 gene, which produces a protein important in recognizing pathogens, called toll-like receptor 7 (TLR7), was markedly higher in B cells from vaccinated female mice compared with vaccinated males. Furthermore, deleting the Tlr7 gene eliminated the male-female differences in immunity. The results of this study, highlighting differences in the immune responses of males and females, underscore the importance of considering sex differences in antibody responses when designing and implementing novel vaccines, including those that target influenza viruses.

Reference: Fink AL, et al. Biological sex affects vaccine efficacy and protection against influenza in mice. Proceedings of the National Academy of Sciences. 2018 Nov 19;115(49):12477–12482.

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