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Use of transmission network scores may guide HIV treatment, prevention
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By mapping the transmission network of HIV in San Diego, researchers were able to predict the likelihood of new HIV transmissions in the city and identify those at highest risk for transmitting the virus.
The findings, published in PLOS ONE, may lead to more targeted treatments and transmission prevention efforts.
“The more we understand the structure and dynamics of an HIV transmission network, the better we can identify ‘hot spots’ of transmission,” study researcher Susan Little, MD, professor of medicine at the UC San Diego AntiViral Research Center, said in a press release. “Not everyone who is HIV-infected is equally likely to transmit the infection to others. There are clusters of more active disease transmission. We can use this information to target treatment interventions to those most likely to transmit the virus to others and markedly reduce the number of new infections.”
In the study, Little and colleagues identified 478 residents of the San Diego area who were newly diagnosed with HIV between 1996 and 2011. Also included in the study were 170 of the HIV patients’ social and sexual contacts. Using genetic sequencing, the researchers evaluated all participants for baseline HIV-1 transmitted drug resistance.
Analysis of the sequenced data enabled the researchers to compare genetic similarities between each participant, identifying connected transmission networks. The researchers then calculated a transmission network score for each of the newly diagnosed individuals. This score was designed to approximate the risk of HIV transmission from the newly diagnosed patient to a new sexual partner.
The researchers found that for 339 participants (52.3%), the sequences were highly similar to sequences collected from at least one other participant. Additionally, there was a strong association between a high transmission network score (within the top 25%) and baseline risk behaviors, such as high numbers of unique sexual partners (P=.014) and insertive, unprotected anal intercourse (P=.0455). Increased risk of transmission was also correlated with a higher transmission network score (P<.0001).
Through a retrospective evaluation of antiretroviral therapy regimens and a model of ART specifically aimed at patients with the highest transmission network score, the researchers found that this targeted therapy would yield significantly reduced HIV transmission at the network level (P<.001).
According to Little, these findings suggest the potential utility of treatment guided by transmission network score.
"Focusing our prevention and treatment resources to the populations at greatest risk of transmission could dramatically reduce the number of new infections associated with these populations," Little said. "Used in conjunction with traditional partner services,
[transmission network score]-guided treatment and prevention interventions could markedly lower rates of new HIV infection in our community."
Disclosure: One of the researchers served as a consultant for Monogram Biosciences and Gen-Probe Inc. Another reported receiving grant funding from ViiV Healthcare and having served as a consultant for Gen-Probe and Testing Talent Services.
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