Can In-house HIV-2 Viral Load Assay be a Reliable Alternative to Commercial Assays for Clinical and Therapeutic Monitoring?

BACKGROUND: Currently, there is a global contemplation to end the AIDS epidemic by 2030. HIV-2 poses unique challenges to this end. The burden of HIV-2 is higher in resource-limited countries, and it is intrinsically resistant to NNRTI drugs. In addition, there is no FDA-approved plasma viral load assay to monitor disease progression and therapeutic efficacy. To overcome these challenges, we have developed and evaluated an in-house quantitative HIV-2 viral load assay. METHODS: Blood samples were collected from 28 HIV-2 treatment-naïve monoinfected individuals and tested using an in-house qPCR HIV-2 viral load assay. The extracted RNA was amplified using Quantifast pathogen + IC kit. RESULTS: The in-house qPCR has a limit of detection of 695 copies/ml. The intra- and inter-assay variation (% CV) of the assay was 0.61 and 0.95, respectively. The in-house assay quantified HIV-2 NIBSC accurately (1000 IU) with a mean of 1952 copies/mL. Among the 28 samples tested by in-house qPCR assay, 11 (39.2%) samples were quantified, whereas 17 (60.7%) samples were not detected. In comparison with Altona RealStar HIV-2 RT PCR and Exavir Load RT assay, the results were 96.4% and 69.6% concordant, respectively. No significant (p = 0.99 and p = 0.13) difference in quantifying viral load between the three assays. Based on clinical and immunological (CD4) staging, the performance characteristics were comparable. CONCLUSION: To the best of our knowledge, this is the first in-house qPCR developed in India. The performance characteristics of the in-house assay are comparable to the commercial assays, and they can be used assertively to monitor HIV-2 patients.

Phylogenetic analysis of partial pre-membrane and envelope sequences of dengue viruses circulating in India.

OBJECTIVE: Phylogenetic characteristics of circulating Indian dengue viruses (DENV) were analysed using partial pre-membrane (PrM) and envelope (E) sequences. An immunodominant region was analysed for mutations, and alignment with common DENV PCR primers and probes was determined. METHODS: Published Indian PrM and E DENV sequences were analysed with hitherto unpublished PrM sequences from this study site. Alignments of DENV were checked for mutations in an immunodominant region and against the commonly used PCR primers and probes. RESULTS: All four serotypes of DENV circulate in India. Genotype (G) GIII and GI of DENV-1 co-circulated in the south with significant PrM mutations before and after 2012. DENV-2 American genotype was first reported after which the Cosmopolitan genotype co-circulated with it in the southwest. The Cosmopolitan strain has been the only DENV-2 genotype circulating, although an Asian American genotype was recently reported. Significant mutations were found in the E region of DENV-2 strains. DENV-3 strains were GIII across the country. DENV-4 GI from the south and west has now spread across India. No significant mutations were found for DENV-3 or DENV-4. Indian strains showed mutations in an immunodominant region of the E gene and in the regions targeted by commonly used PCR primers and probes. CONCLUSIONS: The genetic variability of Indian DENV with co-circulation of multiple genotypes suggests that genotype surveillance is crucial to determining the composition of dengue vaccines and understanding their contribution to epidemiology, virus fitness and pathogenesis. Some mutations seen in an immunodominant region of the E gene may allow these viruses to evade host immune cells. The mutations in the regions targeted by commonly used primers and probes necessitate higher degeneracy.

Quantity of Vaccine Poliovirus Shed Determines the Titer of the Serum Neutralizing Antibody Response in Indian Children Who Received Oral Vaccine.

Replication of oral poliovirus vaccine (OPV) in the intestine (ie, vaccine take) is associated with seroconversion and protection against poliomyelitis. We used quantitative polymerase chain reaction analysis to measure vaccine shedding in 300 seronegative infants aged 6-11 months and in 218 children aged 1-4 years 7 days after administration of monovalent or bivalent OPV. We found that the quantity of shedding correlated with the magnitude of the serum neutralizing antibody response measured 21 or 28 days after vaccination. This suggests that the immune response to OPV is on a continuum, rather than an all-or-nothing phenomenon, that depends on efficient vaccine virus replication.