Changing trends in circulating rotavirus strains in Pune, western India in 2009-2012: emergence of a rare G9P[4] rotavirus strain.

ABSTRACT

BACKGROUND: A vast diversity in rotaviruses at inter- and intra-genotypic level underscores the need for monitoring of circulating rotavirus strains. The aim of this study was to update the data on rotavirus disease and strains for the period from January 2009 to December 2012 in Pune, western India which has been one of the sites of the Indian Rotavirus Strain Surveillance Network since November 2005. METHODS: Children aged <5 years admitted for acute gastroenteritis in three different hospitals from Pune city were included in the study. The stool specimens were collected and tested for rotavirus antigen by a commercial enzyme immunoassay. The rotavirus strains were genotyped by multiplex reverse transcription polymerase chain reaction. RESULTS: During the study period, we found 35.1% of 685 stool specimens contained rotavirus antigen. Frequency of rotavirus detection was greatest (58.5%) among children aged 7-12 months. The G1P[8] (31.4%), G2P[4] (20.2%) and G9P[8] (11.8%) strains were the most common types. We noted predominance of G1P[8] strains (39.6%-46.1%) in all the years of study except 2009 wherein G9P[8] strains scored highest level (15.3%). Subsequent to this, we identified G9P[8] strains at the second highest position in 2010, their sudden decline and rise in G9P[4] strains in 2011-2012. We detected G12 strains in combination with P[6] and P[8] at variable rates (0-10.2%) and highest level (27.1%) of mixed rotavirus infections in 2009 as compared to 2010-2012 (0-3.8%). CONCLUSION: The study highlights the huge burden of rotavirus disease and changing profile of circulating rotavirus strains displaying emergence of G9P[4] reassortant strains in Pune, western India and emphasizes the need to analyze the entire genomic constellation of rotavirus strains for better evaluation of the impact of rotavirus.