The researchers found three important disease-specific features that appear key for the production of broadly neutralizing antibodies: the number of viruses present in the body, the diversity of virus types, and how long the HIV infection had gone untreated.
Huldrych Günthard, professor of clinical infectious diseases at UZH and one of the study's corresponding authors, says their study is the first to identify these three disease-specific features.
He says they also found that the features influence the production of broadly neutralizing antibodies independently of each other, and explains:
"So we don't necessarily have to consider all three parameters in designing an HIV vaccine. This is especially important with regard to the length of vaccine administration - it wouldn't be possible to imitate a longer untreated HIV infection with a vaccine."
The important host-specific feature concerns ethnicity. The team found black participants infected with HIV appear to make broadly neutralizing antibodies more frequently than white people - regardless of other factors the study analyzed.
Co-author Alexandra Trkola, a professor of medical virology at UZH, suggests this factor needs further investigation in order to better understand how ethnic origin affects production of broadly neutralizing HIV antibodies. Factors likely to play a role could be genetics, geographics, and socioeconomics.
Finally, the team found that different virus subtypes appear to affect the binding site the antibodies attach to. Subtype B viruses are more likely to spur the body to make HIV antibodies that bind to CD4 binding sites - through which the virus binds to host immune cells.