NIAID Now | July 04, 2019
To help fight a virus, the body relies on proteins called antibodies to activate immune responses at the site of infection. Developing effective vaccines against sexually transmitted infections (STIs), including herpes simplex virus (HSV), has been difficult, in part due to the inefficient process by which antibodies reach the female reproductive tract at the time of infection.
HSV causes genital herpes, an STI that is common in the United States and has no cure. In an NIAID-funded research study, scientists explored why standard vaccination strategies have failed to trigger effective immune responses in the vaginal cavity, where they are needed to fight STIs including HSV.
In this study, scientists used mice to test vaccination strategies that may elicit antibodies against one type of HSV, herpes simplex virus 2 (HSV-2). They found that standard subcutaneous injection (injection under the skin) of an HSV-2 vaccine did not confer protection against vaginal HSV-2 infection and did not lead to production of antibodies in the vaginal cavity, even though high levels of antibodies against HSV-2 were circulating in the blood. In contrast, when the vaccination was administered locally (vaginally), re-exposure to HSV-2 led to large amounts of specialized immune cells called memory B cells entering the vaginal area and secreting HSV-2 antibodies. The researchers determined that this memory B-cell movement toward the site of infection was critical for the development of local antibody responses needed to fight infection. In addition, they identified key characteristics of the memory B cells that enable these cells to travel into the vaginal cavity in response to infection.
This study provides critical insight into immune response pathways needed to generate immunity to infections in the female reproductive tract. Using these new insights, researchers may be able to develop improved vaccines that provide powerful protection against STIs including HSV-2.
Reference: Eun Oh JE et al. Migrant memory B cells secrete luminal antibody in the vagina. Nature. 2019 July 4; 571(7763):122–126.