Our bodies are 90% microbial and 10% human: fact or fiction? You may call me on shenanigans (or a much more censored word), but it is indeed a fact. Though there are millions of bacteria in the world that cause disease, there are also millions of bacteria in our bodies that help us throughout our daily lives. For example, Escherichia coli in our intestines help us absorb nutrients from our food, and Streptococcus salivarius in our mouths defend against Streptococcus pyogenes, the culprit behind strep throat.
In a recent study led by Sam Lai, assistant professor of pharmacy and engineering at University of North Carolina at Chapel Hill, a particular type of vaginal bacteria, Lactobacillus crispatus, has been found to protect against HIV and other sexually transmitted infections. Researchers collected samples of cervicovaginal mucus (CVM) from 31 women of reproductive age and introduced fluorescent HIV pseudovirus particles into each sample. High-resolution microscopy was then used to observe the reaction between bacteria colonizing CVM and HIV.
Image Source: Peter Dazeley
Among all of the CVM samples, there were two broad categories of CVM that the researchers discovered–CVM that was susceptible to HIV pseudovirus particles and CVM that was able to trap them within the mucus layer. When researchers isolated the bacteria within each category, they discovered that the samples with CVM capable of trapping HIV pseudovirus particles contained a large amount of Lactobacillus crispatus. Though it remains unclear how Lactobacillus crispatus is better at trapping HIV than other bacteria, Dr. Lai and his associates hypothesize that Lactobacillus crispatus may cause CVM to become sticky to the point that it is able to restrain HIV particles.
If the researchers are able to find a way to select for Lactobacillus crispatus in CVM, they may be able to produce some sort of “biological condom” that can help protect against HIV and other STIs. But for now, the rubber ones will have to do.