Blocking Milk-Borne HIV Transmission by Virus-Capturing Lactobacilli

1Lavax, Palatine, IL, 2University of Illinois - Chicago, Chicago, IL, 3Rush University, Chicago, IL, 4University of Connecticut, Farmington, CT

Objectives: Breastfeeding contributes to mother-to-child transmission (MTCT) of HIV. An effective prophylaxis is not yet available for blocking this route of transmission. Here we propose to develop a novel HIV prophylaxis using virus-capturing lactobacilli to block MTCT of HIV through breastfeeding.

Methods: Oral lactobacilli were isolated from the saliva of healthy human subjects. To screen for virus-capturing strains, the bacteria were analyzed for the capacity to bind to the HIV envelope, capture HIV, block its infection in vitro, and consume gp120 as a nutrient. For bacterial preservation, a freeze-dry protocol was developed to maintain Lactobacillus viability at high temperatures. Also, the safety of the virus-capturing lactobacilli was evaluated by a 90-day rat-feeding study.

Results: Among hundreds of oral Lactobacillus isolates, 6 strains bound to gp120 by lectin-sugar interaction. Two were further analyzed for capturing live HIV viruses. One strain, AF51, effectively blocked HIV infection in vitro. Nutrient acquisition and preference analyses showed that among gp120, milk proteins, and mucin, AF51 captured gp120 and consumed it as a more preferred nutrient. The viability of AF51 was preserved for up to 3 months at 33°C by a new freeze-dry method. Its safety was confirmed by a 90-day rat feeding study.

Conclusions: We have isolated an exceptional oral Lactobacillus strain that has the ability to capture HIV in milk and to block HIV infection in vitro. We have formulated the probiotic to resist warm temperatures and confirmed its safety in animals. Our next step is to test this novel probiotic in animal models and infants for studying the blockage of milk-borne HIV transmission in vivo. Supported by IADR/GSK Innovation in Oral Care Award and NIH grant AI068528.