Background Current public health efforts often use molecular technologies to identify and contain communicable disease networks, but not for HIV. Here, we investigate how molecular epidemiology can be used to identify highly-related HIV networks within a population and how voluntary contact tracing of sexual partners can be used to selectively target these networks. Methods We evaluated the use of HIV-1 pol sequences obtained from participants of a community-recruited cohort (n=268) and a primary infection research cohort (n=369) to define highly related transmission clusters and the use of contact tracing to link other individuals (n=36) within these clusters. The presence of transmitted drug resistance was interpreted from the pol sequences (Calibrated Population Resistance v3.0). Results Phylogenetic clustering was conservatively defined when the genetic distance between any two pol sequences was <1%, which identified 34 distinct transmission clusters within the combined community-recruited and primary infection research cohorts containing 160 individuals. Although sequences from the epidemiologically-linked partners represented approximately 5% of the total sequences, they clustered with 60% of the sequences that clustered from the combined cohorts (O.R. 21.7; p=<0.01). Major resistance to at least one class of antiretroviral medication was found in 19% of clustering sequences. Conclusions Phylogenetic methods can be used to identify individuals who are within highly related transmission groups, and contact tracing of epidemiologically-linked partners of recently infected individuals can be used to link into previously-defined transmission groups. These methods could be used to implement selectively targeted prevention interventions.
Reports of a high frequency of the transmission of minority viral populations with drug-resistant mutations (DRM) are inconsistent with evidence that HIV-1 infections usually arise from mono-or oligoclonal transmission. We performed ultradeep sequencing (UDS) of partial HIV-1 gag, pol, and env genes from 32 recently infected individuals. We then evaluated overall and per-site diversity levels, selective pressure, sequence reproducibility, and presence of DRM and accessory mutations (AM). To differentiate biologically meaningful mutations from those caused by methodological errors, we obtained multinomial confidence intervals (CI) for the proportion of DRM at each site and fitted a binomial mixture model to determine background error rates for each sample. We then examined the association between detected minority DRM and the virologic failure of first-line antiretroviral therapy (ART). Similar to other studies, we observed increased detection of DRM at low frequencies (average, 0.56%; 95% CI, 0.43 to 0.69; expected UDS error, 0.21 ؎ 0.08% mutations/site). For 8 duplicate runs, there was variability in the proportions of minority DRM. There was no indication of increased diversity or selection at DRM sites compared to other sites and no association between minority DRM and AM. There was no correlation between detected minority DRM and clinical failure of first-line ART. It is unlikely that minority viral variants harboring DRM are transmitted and maintained in the recipient host. The majority of low-frequency DRM detected using UDS are likely errors inherent to UDS methodology or a consequence of error-prone HIV-1 replication.Using standard population-based genotypic assays of HIV from individuals not yet treated with antiretroviral drugs, several studies (43,64,69,76) have estimated the rate of transmitted drug resistance to be between 8 and 27% in countries with the highest rates of antiretroviral therapy (ART) use. In resource-limited settings, in which the introduction of ART has been more recent, the estimated frequency of transmitted drug resistance mutations (DRM) is substantially lower (41). It appears, however, to be increasing in these settings as well (2,14,51). Using more-sensitive genotypic assays, different research groups (15,30,32,37,48,58,65) have reported higher proportions of transmitted DRM in ART-naive individuals. The clinical importance of these low-level DRM remains unclear, as they have been associated with clinical consequences in some (21,24,32,36,37,40,46,54,55,63,66,71) but not all (30, 47, 58) studies.Highly sensitive assays for detecting low-frequency DRM include point mutation assays and high-resolution sequencing techniques. Point mutation assays, such as allele-specific PCR, can detect DRM at frequencies as low as 0.01% of the sampled viral population (31,45,53,54), but they do not provide information about the sequence context surrounding a given DRM and may be prone to false positives at the lower level of detection (22). High-resolution sequencing techniques, such as single ge...
Intrasubtype DI was frequent and comparable to primary infection rates among MSM in San Diego; however, superinfection rates declined over time. DI is likely an important component of the HIV epidemic dynamics, and development of stronger immune responses to the initial infection may protect from superinfection.
Objective To investigate the susceptibilities to and consequences of HIV-1 dual infection (DI). Design We compared clinical, virologic, and immunologic factors between participants who were dually infected with HIV-1 subtype B, and monoinfected (MI) controls who were matched by ongoing HIV risk factor. Methods The viral load and CD4 progressions of dually and singly infected participant groups were compared with linear mixed-effects models, and individual dynamics before and after superinfection were assessed with a structural change test (Chow test). Recombination breakpoint analysis (GARD), HLA frequency analysis, and cytotoxic T-lymphocyte (CTL) epitope mapping were also performed (HIV LANL Database). Results The viral loads of DI participants increased more over 3 years of follow-up than the viral loads of MI controls, while CD4 progressions of the two groups did not differ. Viral escape from CTL responses following superinfection was observed in two participants whose superinfecting strain completely replaced the initial strain. This pattern was not seen among participants whose superinfecting virus persisted in a recombinant form with the initial virus or was only detected transiently. Several HLA types were overrepresented in DI participants as compared to MI controls. Conclusions These results identify potential factors for DI susceptibility and further define its clinical consequences.
Current methods to detect intraclade HIV dual infection are poorly suited for determining its prevalence in large cohorts. To investigate the potential of ultra-deep sequencing to screen for dual infection, we compared it to bulk sequence-based synonymous mixture index and the current standard of single genome sequencing. The synonymous mixture index identified samples likely to harbor dual infection, while ultra-deep sequencing captured more intra-host viral diversity than single genome sequencing at approximately 40% of the cost and 20% of the laboratory and analysis time. The synonymous mixture index and ultra-deep sequencing are promising methods for rapid and cost-effective systematic identification of HIV dual infection.
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