Genomic Diversity of Group A Rotavirus Strains Infecting Humans in Eastern India

Abstract

(1.25%), were also detected during this study period. Twenty two percent of specimens showed mixed infections, 38 (24%) of the total samples remained untypeable for either VP7 or VP4, while only 4 (2.5%) of the samples were untypeable for both genes. Eleven specimens collected from Manipur were also genotyped and revealed a very high degree of genomic reassortment.Group A rotaviruses are the major cause of severe dehydrating gastroenteritis among human infants and young of a wide variety of mammalian and avian species (17), and it has been estimated that nearly a million deaths occur every year (9, 20), predominantly in developing countries.Fifteen G serotypes of rotaviruses (27) are recognized, depend on the molecular characterization of VP7 (glycosylated outer capsid protein). However, G1 to G4 are the most predominant genotypes in humans. Moreover, a number of unusual genotypes, G5, G8, and G9, have also been reported recently from various countries (8). Thirteen P serotypes (22) and 21 P genotypes are recognized on the basis of VP4 (protease-sensitive outer capsid protein), but the most common P serotypes infecting humans are P1A and P1B, corresponding to the P[8] and P[4] genotypes, respectively. Although the role of VP4 protein in protective immunity is not very well established, information on G and P typing is important for identifying unusual or new virus strains circulating in different populations (19).The first human rotavirus vaccine (a human-animal tetravalent vaccine) was licensed in the United States in 1998; however, the same vaccine has not been tried extensively in other countries. Due to strain diversity in different parts of the world, knowledge of molecular epidemiology and antigenic diversity of rotaviruses in circulation is imperative for the development of a suitable, efficacious vaccine to combat rotaviral diarrhea. Therefore, in this study we report the characterization of different G and P types of rotavirus strains circulating in a particular area of India.

Rotavirus Infection: A Perspective on Epidemiology, Genomic Diversity and Vaccine Strategies

“…In a study from Kolkata (1998Kolkata ( -2000, the most predominant genotype was G1P [8], followed by G2P [4] and G4P [8]. A number of uncommon genotypes, G1P [4], G2P [8], G2P [6], G4P [4], and G4P [6] were also observed [29]. A novel rotavirus strain G4P [8] was also reported from children with acute diarrhea during that study.…”

“…This process occurs in vitro in mixed infections with different strains of Group A rotavirus and has also been used to study gene-protein assignment [17,76]. Comparison of various unusual strains and comparing their gene homology has provided ample evidence that reassortment also occurs in vivo resulting in large number of variants co existing in nature [17,27,29,74,84,93,100].…”

“…However, uncommon strains like G1P [4], G2P [8], G4P [4], G9P [6] and G9P [8] were found in smaller frequencies. In contrast, an epidemiological survey conducted in India from 1986 to 1988, showed that 70% of strains belonged to the unusual combination of G9P [11] [29,74]. A survey conducted in 1993 showed equal distribution of the common strain G2P [4] and the unusual strain G9P [6], which were found in 21 and 24% of isolates, respectively in India [4,74].…”

“…In some other cases the genetic relatedness determined through nucleotide sequencing has suggested an animal rotavirus as the likely origin of human isolates [17,38,84]. There have been many reports of human rotaviruses with unusual combinations of subgroup, G-P-type, suggesting considerable diversity among rotavirus strains worldwide [25,29,35,36,82]. Moreover, there are also reports of unusual strains such G5, G8 and G10 occurring locally in certain parts of world [25,29,30,36].…”

“…There have been many reports of human rotaviruses with unusual combinations of subgroup, G-P-type, suggesting considerable diversity among rotavirus strains worldwide [25,29,35,36,82]. Moreover, there are also reports of unusual strains such G5, G8 and G10 occurring locally in certain parts of world [25,29,30,36]. These findings indicate that there is a huge diversity of rotaviruses circulating in humans and, more importantly in the context of public health, animal strains have also been found to be the cause of infections in humans.…”