Pao D, Fisher M, Hue S, Dean G, Murphy G, Cane PA, et al. Transmission of HIV-1 during primary infection: relationship to sexual risk and sexually transmitted infections

University of Birmingham, Birmingham, England, United Kingdom
AIDS (Impact Factor: 5.55). 02/2005; 19(1):85-90. DOI: 10.1097/00002030-200501030-00010
Source: PubMed


To study primary HIV-1 infections (PHI) using molecular and epidemiological approaches in order to assess correlates of transmission in this population.
Individuals with PHI were recruited prospectively from a discrete cohort of 1235 individuals under follow-up in a well-defined geographical area between 1999 and 2003. PHI was diagnosed by one of the following: negative HIV antibody test within 18 months, evolving antibody response, or application of the serological testing algorithm for recent HIV seroconversion. The pol gene was sequenced to identify genotypic resistance and facilitate molecular epidemiological analysis. Clinical data were collected and linked in an irretrievable fashion when informed consent was obtained.
A total of 103 individuals with PHI diagnosed between 1999 and 2003 were included in the study; 99 (96%) were male and 90 (91%) were men who have sex with men. Viruses from 35 out of 103 (34%) appeared within 15 phylogenetically related clusters. Significant associations with clustering were: young age, high CD4 cell count, number of sexual contacts, and unprotected anal intercourse (UAI) in the 3 months before diagnosis (P < 0.05 for all). High rates of acute sexually transmitted infections (STI) were observed in both groups with a trend towards higher rates in those individuals with viruses within a cluster (42.9 versus 27.9%; P = 0.13).
High rates of partner change, UAI and STI are factors that facilitate onward transmission during PHI. More active identification of individuals during PHI, the management of STI and highly active antiretroviral therapy may all be useful methods to break transmission networks.

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    • "Even after an average of 19 months of observation and nearly 9 years of follow-up, divergence remained below 2% for all mono-infected individuals. These findings indicate that the 1% genetic distance cutoff invoked in previous epidemiological linkage studies is likely a conservative estimate to infer individuals belonging to the same transmission network [32], [33], [34]. "
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    • "Partial HIV-1 pol gene sequences routinely obtained for genotypic drug resistance testing are adequate to infer transmission events and to characterize epidemiological patterns of public health relevance (Hué et al., 2004). Phylogenetic analyses have been used to understand the contribution of recent HIV infections to onward transmission (Brenner et al., 2007; Pao et al., 2005), drug-resistance transmission in untreated populations (Brenner et al., 2008; Callegaro et al., 2011; Hué et al., 2009; Skoura et al., 2011; Yerly et al., 2009), HIV transmission in specific risk groups like MSM (Fisher et al., 2010; Lewis et al., 2008; Zehender et al., 2010), heterosexual population (Hughes et al., 2009) or injecting drug users (Skar et al., 2011), and the introduction and spread of different HIV-1 subtypes in Western countries (Gifford et al., 2007; von Wyl et al., 2011). Specifically , Bayesian Markov chain-Monte Carlo (MCMC) approaches that include molecular clock models have greatly contributed by placing HIV-1 transmissions in a real time-frame, allowing the estimation of the origin and tempo of HIV spread (Brenner et al., 2011; Callegaro et al., 2011; Chalmet et al., 2010; Gifford et al., 2007; Hué et al., 2009; Hué et al., 2005; Hughes et al., 2009; Lewis et al., 2008; Zehender et al., 2010). "
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