ABSTRACT
<i>Rotavirus A</i> causes severe diarrhoea in infants and young children worldwide. The migration pattern (electropherotype) of the double-stranded RNA genome upon polyacrylamide gel electrophoresis has been used to define “strains” in molecular epidemiology. In temperate countries, distinct electropherotypes (strains) appear after the annual, off-seasonal interruption of rotavirus circulation. In Nepal, rotavirus circulated year-round and an uncommon genotype G12P[6] predominated and persisted, providing a unique opportunity to examine whether the same electropherotype (the same strain) persisted or new electropherotypes (new strains) emerged successively under the same G12P[6] predominance. A total of 147 G12P[6] rotaviruses, collected from diarrhoeal children in Nepal between 2007 and 2010, were classified into 15 distinct electropherotypes (strains). Of these, three electropherotypes (strains), LP1, LP24, and LP27, accounted for 10%, 32% and 38% of the G12P[6] rotaviruses, respectively. Each of the three major strains successively appeared, dominated, and disappeared. This study provided new evidence for the hypothesis that rotavirus constantly changes its strains to predominate in the local population even under conditions where a single genotype predominates and persists. Such dynamic strain replacement, the constant takeover of one predominant strain by another, fitter strain, is probably gives a competitive edge to the survival of rotavirus in nature.
ABSTRACT
To assess the circulating rotavirus strains among hospitalized children and adults in Gizan City.This cross-sectional study was based in 5 hospitals in the Gizan area. Stool samples were collected between November 2004 and March 2005, from sequential patients with acute, dehydrating diarrhea. Rotavirus antigen was detected in stool by enzyme-linked immunosorbent assay. The diversity of rotavirus strains was investigated using electropherotying and reverse transcription-polymerase chain reaction amplification of the VP7 and VP4 genes [G and P genotyping]. Rotavirus was detected in 54 of 454 [12%] subjects. The ages of those infected with rotavirus ranged from 15 days to 20 years, with a median age of 36 months. The highest rotavirus detection rate [24%] occurred in children aged 48-59 months. Overall, 50 [93%] of strains could be assigned both a G- and P-type; G1P[8] was the most frequently detected strain type [n=48, 89%] with one rotavirus each of G2P[4] and G9P[8]. Rotavirus strains circulating in Gizan would be well covered by current rotavirus vaccines. Rotavirus serotype G9 has been detected in Saudi Arabia for the first time. Continued surveillance of rotavirus strains is required