Priyanka Singh

The first dominant co-circulation of both dengue and chikungunya viruses during the post-monsoon period of 2010 in Delhi, India.

Independent outbreaks of dengue virus (DENV) infection and sporadic cases of chikungunya virus (CHIKV) have been recorded in the metropolitan city of Delhi on several occasions in the past. However, during a recent 2010 arboviral outbreak in Delhi many cases turned negative for DENV. This prompted us to use duplex reverse transcriptase-polymerase chain reaction (D-RT-PCR) to establish the aetiology of dengue/chikungunya through sequencing of CprM and E1 genes of dengue and chikungunya viruses. Interestingly, for the first time, both DENV and CHIKV co-circulated simultaneously and in equally dominant proportion during the post-monsoon period of 2010. DENV-1 genotype III and the East Central South African genotype of CHIKV were associated with post-monsoon spread of these viruses.

Genetic polymorphisms of GSTM1, GSTT1 and GSTP1 and susceptibility to DNA damage in workers occupationally exposed to organophosphate pesticides

GSTM1, T1 and P1 are important enzymes of glutathione S-transferases (GSTs), involved in the metabolism of many endogenous and exogenous compounds. Individual genetic variation in these metabolizing enzymes may influence the metabolism of their substrates. The present study was designed to determine the genotoxic effects using DNA damage and its association with GSTM1, GSTT1, and GSTP1 (Ile105Val) genetic polymorphisms in workers occupationally exposed to organophosphate pesticides (OPs). We examined 230 subjects including 115 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using individual PCR or PCR-RFLP. Significantly higher DNA tail moment (TM) was observed in workers as compared to control subjects (14.41 ± 2.25 vs. 6.36 ± 1.41 tail % DNA, p<0.001). The results revealed significantly higher DNA TM in workers with GSTM1 null genotype than those with GSTM1 positive (15.18 vs. 14.15 tail % DNA, p=0.03). A significantly higher DNA TM was also observed in workers with homozygous Ile-Ile GSTP1 genotype than heterozygous (Ile-Val) and mutant (Val-Val) GSTP1 genotype (p=0.02). In conclusion, the results show that null deletion of GSTM1 and homozygote wild GSTP1 genotype could be related to inter-individual differences in DNA damage arises from the gene-environment interactions in workers occupationally exposed to OPs.

Influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to organophosphate pesticides

Previous studies have revealed that organophosphate pesticides (OPs) are primarily metabolized by xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticides-exposed workers. Present study was designed to determine the influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to OPs. We examined 268 subjects including 134 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using alkaline comet assay and genotyping was done using individual polymerase chain reaction (PCR) or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Acetylcholinesterase and paraoxonase activity were found to be significantly lowered in workers as compared to control subjects which were analyzed as biomarkers of toxicity due to OPs exposure (p<0.001). Workers showed significantly higher DNA tail moment (TM) compared to control subjects (14.32±2.17 vs. 6.24±1.37 tail % DNA, p<0.001). GSTM1 null genotype was found to influence DNA TM in workers (p<0.05). DNA TM was also found to be increased with concomitant presence of NAT2 slow acetylation and CYP2C9*3/*3 or GSTM1 null genotypes (p<0.05). DNA TM was found increased in NAT2 slow acetylators with mild and heavy smoking habits in control subjects and workers, respectively (p<0.05). The results of this study suggest that GSTM1 null genotypes, and an association of NAT2 slow acetylation genotypes with CYP2C9*3/*3 or GSTM1 null genotypes may modulate DNA damage in workers occupationally exposed to OPs.

Role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to organophosphate pesticides.

Organophosphate pesticides (OPs) are primarily metabolized by several xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticide-exposed workers. The present study was designed to determine the role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to OPs. We examined 284 subjects including 150 workers occupationally exposed to OPs and 134 normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using PCR-RFLP. The results revealed that the PONase activity toward paraoxonase and AChE activity was found significantly lowered in workers as compared to control subjects (p<0.001). Workers showed significantly higher DNA damage compared to control subjects (14.37±2.15 vs. 6.24±1.37 tail% DNA, p<0.001). Further, the workers with CYP2D6*3PM and PON1 (QQ and MM) genotypes were found to have significantly higher DNA damage when compared to other genotypes (p<0.05). In addition, significant increase in DNA damage was also observed in workers with concomitant presence of certain CYP2D6 and PON1 (Q192R and L55M) genotypes which need further extensive studies. In conclusion, the results indicate that the PON1 and CYP2D6 genotypes can modulate DNA damage elicited by some OPs possibly through gene-environment interactions.

Current research and clinical trials for a vaccine against Chikungunya virus

Correspondence: Mala Chhabra National Centre for Disease Control, 22-Sham Nath Marg, New Delhi 110054, India Tel +91 11 2390 9236 Fax +91 11 2392 2677 Email malachhabra@yahoo.co.in Abstract: Chikungunya infection is a self-limiting Aedes mosquito-borne arboviral disease with variable clinical manifestations, ranging from asymptomatic illness to a very severe and crippling arthralgia. Until recently, Chikungunya was a little known disease that re-emerged in 2005–2006, leading to major outbreaks on the Indian Ocean Islands and in South East Asia, and eventually extending its range to temperate regions. It drew global attention due to its explosive onset, extensive geographic distribution, and high morbidity. Since re-emergence, an estimated one million symptomatic cases with 0.1% fatality per year have been reported globally. A lack of herd immunity, vector control, and globalization and trade are clearly a problem in the spread of this disease. The Chikungunya virus (CHIKV) has also acquired biologically important mutations during its evolution, increasing its geographic reach. This disease has resulted in a loss of productivity in affected communities. The absence of a vaccine or an effective antiviral therapy makes dealing with this disease challenging for those involved in public health. There is an emergent need for an effective vaccine against CHIKV infection. The candidates that have been tested include attenuated living, nonliving and genetically engineered vaccines. Several of these vaccine candidates are in preclinical and clinical trials. This review outlines the current knowledge about chikungunya infection and vaccine development.

Molecular epidemiology of Crimean-Congo haemorrhagic fever virus in India

Crimean-Congo haemorrhagic fever (CCHF) is an emerging zoonotic disease in India which is prevalent in neighbouring countries. CCHF virus (CCHFV) is a widespread tick-borne virus which is endemic in Africa, Asia, Eastern Europe and the Middle East. In the present study, samples of clinically suspected human cases from different areas of northern-western India were tested for the presence of CCHFV by RT-PCR through amplification of nucleocapsid (N) gene of CCHFV. Positive samples were sequenced to reveal the prevailing CCHFV genotype(s) and phylogenetic relatedness. A phylogenetic tree revealed the emergence of diverse strains in the study region showing maximum identity with the Pakistan, Afghanistan and Iran strains, which was different from earlier reported Indian strains. Our findings reveal for the first time the emergence of the Asia 1 group in India; while earlier reported CCHFV strains belong to the Asia 2 group.

Continued persistence of ECSA genotype with replacement of K211E in E1 gene of Chikungunya virus in Delhi from 2010 to 2014

Abstract Chikungunya is a viral disease caused by arthropod-borne Chikungunya virus (CHIKV) and transmitted by Aedes mosquitoes. In 2006, CHIKV re-emerged in Indian Ocean islands, Southeast Asia and India. Delhi witnessed the continued occurrence of CHIKV after its first outbreak in 2010. The constant monitoring of the circulating strains of CHIKV is important for designing and executing control strategies. Therefore, the present study was undertaken to unveil the genomic changes of CHIKV in Delhi during the period 2010–2014. RT-PCR of nsP1 and E1 gene region of CHIKV was performed for diagnosis and mutational study, respectively. Positive CHIKV samples were processed for the nucleotide sequence of E1 gene region. Nucleotide alignments of study sequences revealed both synonymous and non-synonymous mutations, although amino acid alignments of all study sequences had single amino acid replacement lysine (K) by glutamic acid (E) at position 211 in E1 gene. A phylogenetic analysis revealed that all the study sequences clustered in East, Central and South African genotype of CHIKV. The same strain of East, Central and South African genotype is circulating in this region during the period 2010–2014.

Molecular characterization of DENV-3 circulating during the post-monsoon period of 2013–14 in Delhi, India

The present study characterizes the recently circulating DENV-3 strain in the metropolitan city of Delhi during post monsoon period of 2013-14. Partial molecular characterization of 12 DENV3 isolates was carried out on the basis of envelope (E) and non-structural 1 (NS1) gene regions. Phylogenetic analysis showed all these 12 isolates grouped under lineage III of genotype III with recent isolates from China and Pakistan. The point mutation L430I in the Env region appears to be the unique molecular signature for the 2013 strains. Another unique substitution, I167V in NS1 protein was observed in a single isolate among those 12 samples. The study describing the molecular characterization could be significant if these unique substitutions cause the poor B cell responses.