No vaccine is highly effective against tuberculosis (TB)—the predominantly respiratory disease caused by infection with Mycobacterium tuberculosis (Mtb) bacteria and that causes about 1.3 million deaths each year. Increasing evidence suggests that antibodies can protect against Mtb infection, but knowledge regarding these potentially protective antibodies is lacking.

In a paper published online on December 12, 2023, in eBioMedicine, Jacqueline Achkar, M.D., M.S., Elise Ishida, and colleagues evaluated airway and serum samples of 57 macaque monkeys that had undergone low-dose Mtb airway infection; 36 of  the animals developed latent Mtb infection (i.e., no symptoms and no signs of disease), and 21 developed active TB (the disease which can be transmitted and result in death). The researchers assessed levels of several types of antibodies in the macaques before infection, 2-3 months after, and 5-6 months after infection. Compared with macaques with active TB, those with latent Mtb infection had much stronger antibody responses. More specifically, latently infected macaques had significantly increased (1) airway and plasma IgA against specific Mtb glycan antigens prior to infection; (2) plasma IgG reactivity to the Mtb protein MTB32A early post-infection; and (3) airway IgG responses to certain Mtb proteins early postinfection. The results suggest that latently infected macaques may have been protected against active infection due to pre-existing antibodies from prior exposure to non-TB-causing mycobacteria (which have been found to bolster protection against TB in experiments involving mice). If so, these findings could inform strategies for developing more effective TB vaccines.

Dr. Achkar is professor of medicine, and of microbiology & immunology, director of global health research at the Global Health Center, associate director for translational research at the Clinical Research Training Program (CRTP) at Einstein, and an attending physician at Montefiore Medical Center. The study’s first author is Elise Ishida, a Ph.D. student in Dr. Achkar’s lab who recently graduated.