ABSTRACT
Human astroviruses (HAstVs) associated with acute watery diarrhea among hospitalized infants, children and adults as sole or mixed infection, were earlier reported from Kolkata, India. Further, novel recombinations have been detected through sequencing of the highly conserved ORF1b (RdRp) region of seven human astrovirus strains in Kolkata, India. Primers were designed and the ORF1b region was amplified by RT-PCR and sequenced. To examine the evolutionary pressures influencing the evolution of human astroviruses we implemented evolutionary genetics analysis. Maximum recombination break points detected in Kolkata strain IDH1300 were 8 and a single break point location was detected at 1205nt position. Partition-wise phylogenetic analyses of the IDH1300 Kolkata strain did not show close homology to the reference strains. Further phylogenetic analyses of full length ORF1b region of the seven human astrovirus strains showed that they formed a close cluster with each other and displayed a separate lineage in comparison to reference human astrovirus strains worldwide. This study shows the emergence of novel recombinant human astrovirus strains in Kolkata, India, warranting stringent surveillance to monitor the genetic diversity of human astrovirus strains infecting different age groups.
Subject(s)
Astroviridae Infections/genetics , Diarrhea/virology , Gastroenteritis/virology , Mamastrovirus/classification , Mamastrovirus/genetics , Adult , Base Sequence , Child , Feces/virology , Genetic Variation , Genotype , Humans , India , Infant , Open Reading Frames/genetics , Phylogeny , Recombination, Genetic/genetics , Sequence Analysis, DNA , SerotypingABSTRACT
Human astroviruses (HAstVs) have now emerged as another common cause of non-bacterial acute gastroenteritis (AGE) in humans worldwide. This study investigated the epidemiology and genetic diversity of human astrovirus strains circulating among infants, younger children (up to 6 years), older children and adolescents (>6-17 years) and adults (18 years and above) hospitalized for diarrhea and their role in AGE in Kolkata, India. A total of 2535 fecal samples were screened for the presence of known enteric viral, bacterial and parasitic etiologies by conventional microbiological assays and molecular methods. The overall incidences of sole or mixed infection of HAstV with known enteric viral, bacterial and parasitic pathogens were detected in 60 cases (2.4%) among all age groups. The clinical symptoms of astrovirus-associated acute watery diarrhea cases were recorded for all sole and mixed infection cases. A high number of sole (n = 13/60 [21.7%]) and mixed infection cases (n = 22/60 [36.7%]) were observed in adults (18 years old or more). Considering all age groups, 18 sole infection cases (n = 18/60 [30%]) and 42 mixed infection cases (n = 42/60 [70%]) with Rotavirus (n = 11/25 [44%]), Vibrio cholerae O1 (n = 6/24 [25%]) Cryptosporidium spp and Giardia lamblia (n = 5/13 [38.4%]) were observed. Further, eleven HAstV samples from infants and children (up to 6 years), children and adolescents (>6-17 years) and adults (18 years and above) were analyzed for their sequences of overlap region between ORF1b (RdRp) and ORF2 (capsid). Among these, ten strains were found to have close genetic relatedness to the Japanese strain HAstV_G1 [AB009985]. Additionally, the IDH2211 Kolkata strain showed a close genetic match with the Thai HAstV_G3 strain [EU363889]. Our study reports show that HAstVs as the sole agent and as mixed infection with other known enteric viral, bacterial, parasitic pathogens are also responsible for AGE among infants, children, adolescents and adults in Kolkata, India.
Subject(s)
Astroviridae Infections/epidemiology , Astroviridae/isolation & purification , Diarrhea/epidemiology , Acute Disease , Adolescent , Adult , Astroviridae/classification , Astroviridae/genetics , Astroviridae Infections/parasitology , Astroviridae Infections/virology , Caliciviridae Infections/epidemiology , Child , Child, Preschool , Coinfection/epidemiology , Coinfection/parasitology , Coinfection/virology , Diarrhea/parasitology , Diarrhea/virology , Feces/virology , Female , Gastroenteritis/epidemiology , Gastroenteritis/parasitology , Gastroenteritis/virology , Genetic Variation , Genotype , Hospitalization , Humans , India/epidemiology , Infant , Male , Molecular Sequence Data , Norovirus/isolation & purification , Parasitic Diseases/epidemiology , Rotavirus/isolation & purification , Rotavirus Infections/epidemiology , SeasonsABSTRACT
Picobirnaviruses (PBV) are small, non-enveloped viruses with a bisegmented double-stranded RNA genome. In this study a PBV strain, PBV/Horse/India/BG-Eq-3/2010, was identified in the faeces of a 10 month old weaned female foal with diarrhoea in January 2010 from Kolkata, India. Surprisingly, sequence comparison and phylogenetic analysis of a short stretch of the RNA dependent RNA polymerase gene revealed close genetic relatedness (> 98% nucleotide identity) to a human genogroup I PBV strain (Hu/GPBV1) detected earlier from the same part of India. Our observations together with earlier findings on genetic relatedness between human and animal PBV warrant further studies on zoonotic potential.
