Per-pathogen virulence of HIV-1 subtypes A, C and D.

HIV-1 subtypes differ in their clinical manifestations and the speed in which they spread. In particular, the frequency of subtype C is increasing relative to subtypes A and D. We investigate whether HIV-1 subtypes A, C and D differ in their per-pathogen virulence and to what extend this explains the difference in spread between these subtypes.

Enhancement of CD4 Binding, Host Cell Entry, and Sensitivity to CD4bs Antibody Inhibition Conferred by a Natural but Rare Polymorphism in the HIV-1 Envelope.

A rare but natural polymorphism in the HIV-1 envelope (Env) glycoprotein, lysine at position 425 was selected as a mutation conferring resistance to maraviroc (MVC) . N425K has not been identified in HIV-infected individuals failing an MVC-based treatment. This study reports that the rare K425 polymorphism in an HIV-1 subtype A Env has increased affinity for CD4, resulting in faster host cell entry kinetics and the ability to scavenge for low cell surface expression of CD4 to mediate entry.

Heating Injection Drug Preparation Equipment Used for Opioid Injection May Reduce HIV Transmission Associated With Sharing Equipment.

Background: London, Canada, experienced an HIV outbreak among persons who inject drugs despite widespread distribution of harm reduction equipment. Hydromorphone controlled-release (HMC) is the local opioid of choice. Injection drug preparation equipment (IDPE; ie, cookers and filters) is often shared and reused because of the perception that there is residual HMC in the IDPE after use.

Sensitive detection of HIV-1 resistance to Zidovudine and impact on treatment outcomes in low- to middle-income countries.

Background: Thymidine analogs, namely AZT (Zidovudine or Retrovir™) and d4T (Stavudine or Zerit™) are antiretroviral drugs still employed in over 75% of first line combination antiretroviral therapy (cART) in Kampala, Uganda despite aversion to prescribing these drugs for cART in high income countries due in part to adverse events. For this study, we explored how the continued use of these thymidine analogs in cART could impact emergence of drug resistance and impact on future treatment success in Uganda, a low-income country.

Methods: We examined the drug resistance genotypes by Sanger sequencing of 262 HIV-infected patients failing a first line combined antiretroviral treatment containing either AZT or d4T, which represents approximately 5% of the patients at the Joint Clinical Research Center receiving a AZT or d4T containing treatment.

Pathogenic infection of Rhesus macaques by an evolving SIV-HIV derived from CCR5-using envelope genes of acute HIV-1 infections.

For studies on vaccines and therapies for HIV disease, SIV-HIV chimeric viruses harboring the HIV-1 env gene (SHIVenv) remain the best virus in non-human primate models. However, there are still very few SHIVenv viruses that can cause AIDS in non-CD8-depleted animals. In the present study, a recently created CCR5-using SHIVenv_B3 virus with env gene derived from acute/early HIV-1 infections (AHI) successfully established pathogenic infection in macaques.

Low-Frequency Drug Resistance in HIV-Infected Ugandans on Antiretroviral Treatment Is Associated with Regimen Failure.

Most patients failing antiretroviral treatment in Uganda continue to fail their treatment regimen even if a dominant drug-resistant HIV-1 genotype is not detected. In a recent retrospective study, we observed that approximately 30% of HIV-infected individuals in the Joint Clinical Research Centre (Kampala, Uganda) experienced virologic failure with a susceptible HIV-1 genotype based on standard Sanger sequencing. Selection of minority drug-resistant HIV-1 variants (not detectable by Sanger sequencing) under antiretroviral therapy pressure can lead to a shift in the viral quasispecies distribution, becoming dominant members of the virus population and eventually causing treatment failure.

Florivores prefer white versus pink petal color morphs in wild radish, Raphanus sativus.

Many hypotheses suggest that pollinators act to maintain or change floral color morph frequencies in nature, although pollinator preferences do not always match color morph frequencies in the field. Therefore, non-pollinating agents may also be responsible for color morph frequencies. To test this hypothesis, we examined whether Raphanus sativus plants with white flowers received different amounts of florivory than plants with pink flowers, and whether florivores preferred one floral color over the other.