Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110029, India.
Rotavirus is the single most important etiological agent of severe diarrheal illness of infants and young children worldwide, claiming between 454,000–705,000 lives each year. Approximately 17% (100,000) of the world's estimated rotavirus associated deaths together with about 400,000 hospitalizations occur each year in India. The prospect that rotavirus diarrhea in children may soon be prevented by vaccines has placed a new priority on understanding the diversity of rotavirus strains and mechanism by which these strains evolve over time. We have characterized rotavirus strains collected in North India from 2000–2007 for G- and P-types by RT-PCR and sequencing. The novel G12 Rotavirus strains recently detected in other countries were first detected in India in 2001 and have emerged as the predominant strains in Delhi during 2005–2007. While the VP7 sequence was highly homologous among G12 strains isolated in Delhi suggesting recent emergence from a common ancestor, the strains had a diverse constellation of other gene segments demonstrating substantial reassortment. For the entire period, the common rotavirus G-types, G1 (26%), G2 (25%) and G9 (14%) comprised 65% of the strains and common P-types; P[4] (19%), P[6] (22%) and P[8] (35%) comprised 76% of the total P types. Of note, we detected a high percentage of unusual (17%) strains and fecal specimens with mixed (12% G, 15% P) rotavirus infections, having a variety of genomic constellations. We identified two novel RV strains with unusual G/P combinations, G2P[11] and G3P[11] for the first time in patients with diarrhea. The study highlights the great diversity among rotaviruses isolated from Indian children, the opportunity for genetic reassortment between strains and the emergence of a novel G12 strain in our country. Due to the demonstrated effect of antigenic diversity on rotavirus vaccines, it will be important to continue careful monitoring of these strains as rotavirus vaccine programs are implemented in India.
