Avinash Choudekar

All India Institute of Medical Sciences, New Delhi, NCT, India

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Publications (3)11.36 Total impact

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    ABSTRACT: Human metapneumovirus (hMPV) causes acute respiratory infections in children and adults. It is classified into two major genetic lineages and each lineage into two sublineages. The purpose of the study was to identify and characterize hMPV in children who presented to the All India Institute of Medical Sciences, New Delhi, India with acute respiratory infection from April 2005 to March 2007. By reverse-transcription polymerase chain reaction, hMPV was detected in 21 (3%) of the 662 nasopharyngeal samples from children with acute respiratory infection and in none of the 120 control children. Seven of the 21 (33%) children infected with hMPV required hospital admission for pneumonia or bronchiolitis. Most hMPV detections were during the winter and spring seasons. The majority (67%, 11/21) of children positive for hMPV were within 24 months of age. Phylogenetic analysis of partial F and N gene and the full G gene sequences showed three sub-lineages of hMPV circulated during the study period, B1, B2, and the novel sub-lineage A2b. The circulation pattern of hMPV genotypes varied by season. Comparison of the F and G genes of eight strains revealed incongruencies in lineage assignments, raising the possibility that recombination had occurred. Sequence analysis also revealed the F gene was relatively conserved whereas the G gene was more variable between the A and B lineages. This study demonstrates that hMPV is an important contributor to acute respiratory infection in children in India, resulting in both outpatient visits and hospitalizations.
    Journal of Medical Virology 10/2011; 83(10):1799-810. DOI:10.1002/jmv.22176 · 2.35 Impact Factor
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    ABSTRACT: Noroviruses (NoVs) are the most common cause of viral gastroenteritis. Their high incidence and importance in health care facilities result in a great impact on public health. Studies from around the world describing increasing prevalence have been difficult to compare because of differing nomenclatures for variants of the dominant genotype, GII.4. We studied the global patterns of GII.4 epidemiology in relation to its genetic diversity. Data from NoV outbreaks with dates of onset from January 2001 through March 2007 were collected from 15 institutions on 5 continents. Partial genome sequences (n=775) were collected, allowing phylogenetic comparison of data from different countries. The 15 institutions reported 3098 GII.4 outbreaks, 62% of all reported NoV outbreaks. Eight GII.4 variants were identified. Four had a global distribution--the 1996, 2002, 2004, and 2006b variants. The 2003Asia and 2006a variants caused epidemics, but they were geographically limited. Finally, the 2001 Japan and 2001 Henry variants were found across the world but at low frequencies. NoV epidemics resulted from the global spread of GII.4 strains that evolved under the influence of population immunity. Lineages show notable (and currently unexplained) differences in geographic prevalence. Establishing a global NoV network by which data on strains with the potential to cause pandemics can be rapidly exchanged may lead to improved prevention and intervention strategies.
    The Journal of Infectious Diseases 10/2009; 200(5):802-12. DOI:10.1086/605127 · 6.00 Impact Factor
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    ABSTRACT: Human caliciviruses (HuCVs) cause gastroenteritis throughout the world. Limited information is available on molecular epidemiology of caliciviruses from developing countries including India. Standardization and evaluation of a two-step multiplex RT-PCR assay for HuCVs and characterization of strains. Two hundred and twenty-six stool samples were collected from children with acute gastroenteritis (AGE) over a one and half year to study the prevalence and diversity of HuCVs in children with AGE in New Delhi, India. A multiplex two-step RT-PCR using 3 sets of external and 4 sets of internal primers from the RdRp gene was standardized for detection of NoVs and SaVs. Molecular characterization of some HuCV strains was done by sequencing followed by phylogenetic analysis. Fifty-nine HuCVs strains were detected in 54 (24%) of the samples; 5 samples had mixed infections. Of these 59 HuCVs, 36 (61%) were norovirus (34 were GGII; 2 were GGI) and 23 (39%) were sapovirus (22 were GGI; 1 was GGII). Phylogenetic analysis of partial RdRp gene of 12 HuCV strains identified three genotypes (GGI/4, GGII/3 and a newly identified GIIb/Hilversum cluster) in NoVs and one genotype (GGI/1) in SaVs. This is one of the few reports from India on detection and characterization of HuCVs by multiplex RT-PCR assay. This assay can be a useful tool for epidemiological studies of HuCV infections.
    Journal of Clinical Virology 08/2008; 43(1):42-8. DOI:10.1016/j.jcv.2008.05.006 · 3.02 Impact Factor