Unusual five amino acid insert within subtype C HIV-1 envelope contributes to dual-tropism (X4R5)

Coreceptor and cytokine concentrations may not explain differences in disease progression observed in HIV-1 clade A and D infected Ugandans

BACKGROUND

The use of cellular coreceptors and modulation of cytokine concentrations by HIV to establish a productive infection is well documented. However, it is unknown whether the expression of these proteins affects the course of HIV clade A and D disease, reported to have different progression rates.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated whether the number of CD4(+) T-cells expressing CCR5 or CXCR4, the density of these coreceptors and concentrations of specific immune proteins linked to HIV pathogenesis vary between individuals infected with HIV clade A or D. We undertook additional analyses stratifying participants by early (CD4>500 cells/µl) or late (CD4<200 cells/µl) disease stage. Whole blood samples were taken from 50 HIV-1 infected individuals drawn from cohorts in rural south-west Uganda. Late stage participants had less than half the number of CD4(+)/CCR5(+) T-cells (p = 0.0113) and 5.6 times fewer CD4(+)/CXCR4(+) cells (p<0.0001) than early stage participants. There was also a statistically significant difference in the density of CXCR4 on CD4(+) cells between clade A and D infected early stage participants (142 [A] vs 84 [D]; p = 0.0146). Across all participants we observed significantly higher concentration of Th(1) cytokines compared to Th(2) (66.4 vs 23.8 pg/ml; p<0.0001). Plasma concentrations of IFNγ and IL-2 were 1.8 and 2.4 fold lower respectively in Late-D infected participants compared to Late-A participants. MIP-1β levels also decreased from 118.0 pg/ml to 47.1 pg/ml (p = 0.0396) as HIV disease progressed.

CONCLUSIONS/SIGNIFICANCE

We observed specific alterations in the abundance of CD4(+)/CCR5(+) and CD4(+)/CXCR4(+) T-cells, and concentrations of immune proteins across different HIV clades and as infection progresses. Our results suggest that these changes are unlikely to explain the observed differences in disease progression between subtype A and D infections. However, our observations further the understanding of the natural progression of non-clade B HIV infection and how the virus adapts to exploit the host environment.

Extreme genetic divergence is required for coreceptor switching in HIV-1 subtype C

BACKGROUND

Coreceptor switching from CCR5 to CXCR4 is less common in subtype C HIV-1 infection than in subtype B for reasons that are unclear. We have examined sequential virus samples from a subtype C-infected child who had evidence of coreceptor switching.

METHODS

To examine HIV-1 envelope evolution towards CXCR4 usage, env sequences were correlated with phenotypic characteristics determined by entry assays, as well as the ability to use alternative coreceptors such as FPRL1, CCR3, CCR8 and others. The value of a phenotype predictor based on V3 sequences was also assessed.

RESULTS

Ninety-three sequences revealed 3 distinct coexistent virus lineages and only some members of one lineage evolved to use CXCR4. These lineages also had diverse alternative coreceptor patterns including the ability to use FPRL1, CCR3, CCR8, APJ, CMKLR1, RDC-1, CXCR6, CCR1, GPCR1, GPR15 and CCR6. Coreceptor switching was associated with extensive and rapid sequence divergence in the V1/V2 region in addition to V3 changes. Furthermore, interlineage recombination within the C2 region resulted in low predictability of a V3 sequence-based phenotype algorithm, and highlighted the importance of V1/V2 and V3 sequences in coreceptor usage.

CONCLUSION

These results suggest that the evolution to coreceptor switching in subtype C infection requires more mutations than other subtypes, and this contributes to the reduced incidence of R5X4 viruses.

Bariatric surgery outcomes in HIV-infected subjects: a case series

Obesity is now a common problem among HIV-infected patients receiving antiretroviral therapy (ART). Gastric bypass surgery may be an option for some patients who have failed diet and therapeutic lifestyle changes, changes in ART or other treatment modalities for HIV/ART-related lipohypertrophy and obesity. However, few data are available regarding HIV-related outcomes after such surgery and its impact on ART tolerability. We present here a case series of seven subjects with HIV infection who underwent bariatric surgery. Viral suppression was maintained in five of the six subjects who were receiving ART prior to surgery, including three subjects who experienced surgical complications. The median (range) decrease in body mass index (BMI) postoperatively was 10 kg/m(2) (6-28 kg/m(2)). Improvements were also seen in serum lipid fractions with median (range) changes in total cholesterol of -19 mg/dL (-61 to +3 mg/dL) and triglycerides of -185 mg/dL (-739 to +35 mg/dL). Four of the subjects had a reduction in their metabolic medication prescriptions postoperatively. Three of the subjects experienced postsurgical complications. Based on our experience, bariatric surgery may provide an effective treatment modality for obesity and its related comorbidities in the HIV-infected population while not sacrificing virologic suppression. Larger studies are needed to verify these results, especially in regards to surgical complications.