The first identification of rotavirus B from children and adults with acute diarrhoea in kathmandu, Nepal

Abstract

Rotavirus B (RVB) in the genus Rotavirus of the family Reoviridae is known to be a cause of acute gastroenteritis among children and adults in parts of Asia including China, India, Bangladesh and Myanmar. In a 15-month surveillance programme between March 2007 and May 2008, 3,080 stool specimens were collected from children and adults with acute gastroenteritis in an infectious disease hospital in Kathmandu, Nepal. In 25 (0.8%) specimens RVB was detected, for the first time in Nepal, by the use of polyacrylamide gel electrophoresis followed by confirmation with reverse-transcription PCR and sequencing. The strains detected in this study had very similar electropherotypes, and their VP7 sequences were almost identical and phylogenetically belonged to the Indo-Bangladeshi lineage which was distinct from the Chinese lineage. Thus, this study showed the circulation of RVB strains belonging to the Indo-Bangladeshi lineage in a broader region than previously documented, suggesting that this phylogenetic divide corresponded to the geographic divide created by the Himalayan Mountains. Further studies may be warranted to identify and characterize the RVB strains in northern Vietnam which is adjacent to southern China with a long and less mountainous border.

Keywords: Acute diarrhoea; Nepal; Rotavirus B.

Fig. 1.

The electropherotypes of the representative RVB strains detected from the faeces of patients with acute diarrhoea in Nepal. The names of strains are indicated on the top of the lane. The approximate position of each of the 11 genome segments for the prototype RVA human strain Wa is indicated to the left of the panel, and that for RVBs is indicated to the right.

Fig. 2.

Monthly distribution of RVB infections in patients with acute gastroenteritis in Nepal from June 2007 to May 2008.

Fig. 3.

A phylogenetic tree for VP7 genes of Nepalese human RVB strains (indicated in boldface with closed circular dots) along with other human RVB strains obtained from the DNA database. The tree was constructed using the neighbour-joining method included in the MEGA 5 software package with bootstrap probabilities after 1,000 replicate trials. The genetic distance is indicated at the bottom. Percent bootstrap support is indicated by the value at each node when the value was 60% or larger. Two porcine RVB strains (accession numbers AB490441, JQ043795) were used as the outgroup but are not shown in the tree. Only the node where the root is located is shown.