A Study Of Molecular Epidemiology On Human Parechovirus(HPeV)

ObjectivesEstablishing and performing the methods for detecting HPeVs from stool samples of hospitalized children for acute gastroenteritis. To grasp the features of epidemiology of HPeV initially in children with and without diarrhea in Lanzhou and argue the association of different HPeV genotypes with acute gastroenteritis. So as to establish the foundation progessively for clarifying the composition of pathogens on children`s acute gastroenteritis and revealing the feature of etiology about HPeV.MethodsTwo hundred and eighty-six children hospitalized with acute gastroenteritis and ninty-eight asymptomatic control subjects who visited the First Hospital of Lanzhou University, between July 2006-June 2007, were enrolled in the study. All of the children were <5 years old. Stool samples were collected and sent to the National Institute for Viral Disease Control and Prevention, China CDC. HPeV was detected and quantified using real-time reverse transcription PCR (RT-PCR), and then directly genotyped by sequencing a nested RT-PCR product. Phylogenetic analyses of the nucleotide of VP3/VP1 partial gene were conducted with MEGA 3.1. All the data were analyzed by SPSS 13.0 statistical software.ResultsHigh prevalence of HPeV was found in both case group and control group. In total, 84 out of 286 (29.4%) hospitalized children and 15 out of 98 (15.3%) asymptomatic children were found infected with HPeV. All the HPeV-positive stool samples, except 9 samples from case group, were successfully genotyped as either HPeV1, 3, 4, 5, 6 or 8. HPeV2 and HPeV7 were not detected. HPeV1 was frequently identified as the predominant strain and accounted for 51.2% (43/84) and 53.3% (8/15) in case and control groups, respectively. HPeV3 was identified as the second predominant strain (29.8%, 25/84) in case group followed by HPeV4 (4.8%, 4/84). In control group, the number of HPeV3 and HPeV4 infections was the same (both 20%, 3/15), while there was only one case of HPeV5 infection identified (6.7%, 1/15). Two cases (2.4%, 2/84) of HPeV6 infection were identified in case group, while in control group there was no HPeV6 infection found. One case (1.2%, 1/84) of HPeV8 infection was identified in case group. Coinfection with other viruses was common in the case group. There was no statistical significance in the difference of viral loads and positive rates of HPeV1 and HPeV3 between the case and control groups. Statistical analysis did not support a correlation between HPeV1, 3 infection and more severe clinical symptoms. In addition, HPeV in a particular sample (no.49330) can not be classified into any known genotypes by phylogenetic analyses and had an amino acid identity of 89.41% and 67.44% with prototype strains respectively.ConclusionsHPeV was highly prevalent both in children with and without gastroenteritis in Lanzhou. But, the results does not support a causative role of HPeV1 and 3 in acute gastroenteritis. And HPeV may act as an opportunistic pathogen in gastrointestinal (GI) tract, just to be reactivated by other viral infections.