Gottlieb, G. S. | Search bioRxiv

bioRxiv2018

The impact of interspecies recombination on human herpes simplex virus evolution and host immune recognition

Among the most ubiquitous of human pathogens, HSV-1 and HSV-2 are distinct viral species that diverged about six million years ago. At least four ancient HSV-1 x HSV-2 interspecies recombination events have affected the HSV-2 genome, with recombinants and non-recombinants at each locus circulating today. Though interspecies recombination has occurred in the past, its importance in HSV evolution remains incompletely defined. Using 255 newly-sequenced and 219 existing HSV genome sequences, we comprehensively assessed interspecies recombination in HSV. The novel recombinants we identify demonstrate that the sizes and locations of interspecies recombination events in HSV-2 are more variable than previously appreciated. One novel recombinant arose in its current host, showing for the first time that interspecies recombination occurs in contemporary HSV populations. We also demonstrate that interspecies recombination affects T-cell recognition of HSV. Our findings indicate that interspecies recombination can significantly influence genetic variation in and host immunologic response to HSV-2.

genomics↗

bioRxiv2017

Agent-based network model predicts strong benefits to youth-centered HIV treatment-as-prevention efforts

We used an agent-based network model to examine the effect of targeting different risk groups with unsuppressed HIV viral load for linkage or re-linkage to HIV-related treatment services in a heterosexual population with annual testing. Our model identifies prevention strategies that can reduce incidence to negligible levels (i.e., less than 0.1 infections per 100 person-years) 20 years after a targeted Treatment-as-Prevention (TasP) campaign. The model assumes that most (default 95%) of the population is reachable (i.e., could, in principle, be linked to effective care) and a modest (default 5% per year) probability of a treated person dropping out of care. Under random allocation or CD4-based targeting, the default version of our model predicts that the TasP campaign would need to suppress viral replication in ~80% of infected people to halt the epidemic. Under age-based strategies, by contrast, this percentage drops to 50% to 60% (for strategies targeting those <30 and <25, respectively). Age-based targeting did not need to be highly exclusive to yield significant benefits; e.g. the scenario that targeted those <25 years old saw ~80% of suppressed individuals fall outside the target group. This advantage to youth-based targeting remained in sensitivity analyses in which key age-related risk factors were eliminated one by one. As testing rates increase in response to UNAIDS 90-90-90 goals, we suggest that efforts to link all young people to effective care could be an effective long-term method for ending the HIV epidemic. Linking greater numbers of young people to effective care will be critical for developing countries in which a demographic \"youth bulge\" is starting to increase the number of young people at risk for HIV infection.

epidemiology↗