Genogroup characterization of reemerging serotype G9 human rotavirus strain 95H115 in comparison with earlier G9 and other human prototype strains

Phylogenetic analyses of the VP4 and VP7 genes of porcine group A rotaviruses in Sao Paulo State, Brazil: first identification of G5P[23] in piglets

This study determined the group A rotavirus occurrence in pig farms from 7 different cities in São Paulo State, Brazil. Out of 143 samples, 70 tested positive. Sequence analyses of 37 strains indicated that the strains had the G3, G5, G9, and P[6], P[13]/P[22]-like, and P[23] genotypes.

Molecular epidemiology of G9 rotaviruses in Taiwan between 2000 and 2002

Since the mid-1990s, novel G9 rotaviruses have been detected in many countries, suggesting that G9 is a globally important serotype. The molecular epidemiology of G9 rotaviruses in Taiwan from 2000 to 2002 was investigated in this study. G9 rotavirus first appeared in 2000 with 4 cases and constituted 33.8% and 54.8% of the rotavirus-positive samples in 2001 and 2002, respectively. These G9 strains belonged to P[8]G9, subgroup II, and long electropherotype, except one belonged to P[4]G9, subgroup II, and short electropherotype. Nucleotide sequencing and phylogenetic analysis of 52 Taiwanese G9 rotaviruses showed that the VP7 genes shared a high degree of identity to overseas G9 rotaviruses detected after 1993 and that the VP8* portions of the VP4 genes were more closely related to those of local rotaviruses of other G types. The two P[8]G9 strains with high nucleotide identities in the VP7 and the partial VP4 genes, 01TW591 of Taiwan from 2001 and 95H115 of Japan from 1995, varied in four genes, genes 2, 3, 7, and 8, which was revealed by RNA-RNA hybridization. Representative strains for different RNA patterns were also analyzed in the partial VP2 and VP3 genes; the nucleotide identities were high between Taiwanese G9 strains and local G3 or G2 strains. These results suggested that Taiwanese G9 rotaviruses possibly had evolved through reassortment between overseas G9 strains and circulating rotaviruses of other G types.

Epidemiological profile of rotavirus infection in the Republic of Korea: results from prospective surveillance in the Jeongeub District, 1 July 2002 through 30 June 2004

To facilitate future decisions regarding the usefulness of rotavirus vaccines in the Republic of Korea, active surveillance was conducted in a network of clinics, emergency departments, and hospitals serving Jeongeub District, Korea. Children with diarrhea underwent standard clinical evaluations, and stool specimens were collected to test for the presence of rotavirus. Parents were interviewed to collect demographic and family information. From 1 July 2002 through 30 June 2004, a total of 4106 children, representing 1 (50%) of every 2 children <5 years old in the study population, were evaluated for rotavirus diarrhea. Of the 2232 stool specimens obtained throughout the year, 460 (20.6%) were rotavirus positive; however, the monthly prevalence of rotavirus infection peaked at 49.5% in February 2004. Of the 460 rotavirus-positive stool specimens, 366 were obtained from children who visited outpatient clinics, and 94 were obtained from children who were hospitalized. By extrapolating the proportion of rotavirus-positive patients to all children with diarrhea in the surveillance system, we calculate that 882 children in Jeongeub District had rotavirus infection (which would predict that there would be 702 associated clinic visits and 180 hospitalizations). Genotyping of rotavirus strains showed that 39% of strains were type G9P[8], 24% were type G1P[8], 17% were type G3P[8], and 13% were type G2P[4]. The incidence of rotavirus diarrhea peaked at age 13-24 months, and 94% of cases occurred during the first 3 years of life. The annual incidence of all rotavirus disease-associated outcomes was 56.9 cases/1000 children <5 years old (95% confidence interval [CI], 51.9-62.2 cases/1000 children <5 years old). The incidence of rotavirus disease-associated hospitalizations was 11.6 cases/1000 children <5 years old (95% CI, 9.5-14.2 cases/1000 children <5 years old). In Korea, diarrhea is common during childhood, and the incidence of diarrhea due to rotavirus infection suggests that improved programs for the prevention and control of both rotavirus diarrhea and diarrhea due to other causes are needed.

Predominance of porcine rotavirus G9 in Japanese piglets with diarrhea: close relationship of their VP7 genes with those of recent human G9 strains

Type G9 of group A rotavirus (GAR) was shown to be predominant in a survey of VP7 (G) and VP4 (P) genotypes among porcine GARs associated with outbreaks of diarrhea in young pigs in Japan between 2000 and 2002. Comparison of the G9 VP7 gene sequences showed that the porcine G9 strains were more closely related to human G9 strains reemerging globally since the mid-1990s than to those from the mid-1980s. The VP7 gene sequences of porcine G9 strains from different farms were divergent (6.1 to 7.2% difference in nucleotides), suggesting that these G9 VP7 genes were not the result of recent introduction into the porcine population. Regarding the P genotype specificities of porcine G9 strains, while the majority of strains were close to unusual porcine P types (P[13] and P[23]), two strains were of the P[6] type, which has closer sequence identity with the human AU19 strain than with the porcine Gottfried strain. These unexpected results suggest that G9 GARs in the porcine population have spread more widely than previously thought and that the VP7 genes of porcine G9 strains and those of some human G9 strains detected recently may have a common progenitor.

A porcine G9 rotavirus strain shares neutralization and VP7 phylogenetic sequence lineage 3 characteristics with contemporary human G9 rotavirus strains

Of five globally important VP7 (G) serotypes (G1-4 and 9) of group A rotaviruses (the single most important etiologic agents of infantile diarrhea worldwide), G9 continues to attract considerable attention because of its unique natural history. Serotype G9 rotavirus was isolated from a child with diarrhea first in the United States in 1983 and subsequently in Japan in 1985. Curiously, soon after their detection, G9 rotaviruses were not detected for about a decade in both countries and then reemerged in both countries in the mid-1990s. Unexpectedly, however, such reemerged G9 strains were distinct genetically and molecularly from those isolated in the 1980s. Thus, the origin of the reemerged G9 viruses remains an enigma. Sequence analysis has demonstrated that the G9 rotavirus VP7 gene belongs to one of at least three phylogenetic lineages: lineage 1 (strains isolated in the 1980s in the United States and Japan), lineage 2 (strains first isolated in 1986 and exclusively in India thus far), and lineage 3 (strains that emerged/reemerged in the mid-1990s). Currently, lineage 3 G9 viruses are the most frequently detected G9 strains globally. We characterized a porcine rotavirus (A2 strain) isolated in the United States that was known to belong to the P[7] genotype but had not been serotyped by neutralization. The A2 strain was found to bear serotype G9 and P9 specificities as well as NSP4 [B] and subgroup I characteristics. By VP7-specific neutralization, the porcine G9 strain was more closely related to lineage 3 viruses than to lineage 1 or 2 viruses. Furthermore, by sequence analysis, the A2 VP7 was shown to belong to lineage 3 G9. These findings raise intriguing questions regarding possible explanations for the emergence of variations among the G9 strains.

Molecular epidemiology of viral gastroenteritis in Asia

Acute gastroenteritis is one of the most common diseases in humans, and continues to be a significant cause of mortality and morbidity worldwide. Recently the estimates of mortality associated with diarrhea declined, however the majority of deaths still occur in developing countries and thus urgent intervention is needed for the prevention of these diseases. In Asian countries it is very important to study the distribution, transmission and characteristics of prevalent viruses in order to produce viral vaccines. The viruses which cause gastroenteritis are primarily from four distinct families - group A rotaviruses, caliciviruses, enteric adenoviruses and astroviruses. Rotavirus is a common virus that causes severe gastroenteritis in children <5 years of age. The reassortant viruses with animal virus, or directly animal viruses are isolated in humans. The future development of a safe and effective vaccine against rotavirus, along with the expansion of understanding of the distribution of types in Asia and an availability of rapid diagnostic tests, could reduce mortality and might be able to prevent severe gastroenteritis. Calicivirus is a causative virus of acute gastroenteritis in children and has been known to contaminate food causing viral outbreaks affecting people of all ages. Recently, the understanding of calicivirus and the improvement of detection techniques has increased the total frequencies of diarrheal viruses. For the future control and prevention of diarrheal diseases it is necessary to examine the molecular epidemiology of caliciviruses as well as rotaviruses.

Characterization of serotype G9 rotavirus strains isolated in the United States and India from 1993 to 2001

The emergence of rotavirus serotype G9 as a possible fifth globally common serotype in the last decade, together with its increasing detection in association with various genome constellations, raises questions about the origins and epidemiological importance of recent G9 isolates. We examined a collection of 40 G9 strains isolated in the United States from 1996 to 2001 and in India since 1993 to determine their VP7 gene sequences, P types, E types, subgroup specificities, and RNA-RNA hybridization profiles. With the exception of two U.S. strains, all of the study strains shared high VP7 gene sequence homology (<2.5% sequence divergence on both the nucleotide and amino acid levels) and were more closely related to other recent isolates than to the first G9 strains isolated in the 1980s. The VP7 gene sequence and RNA-RNA hybridization profiles of the long-E-type strains showed greater variation than the short-E-type strains, suggesting that the latter strains are the result of a relatively recent reassortment event of the G9 VP7 gene into a short-E-type lineage. No evidence for reassortment of genes other than VP4 and VP7 between major human rotavirus genogroups was observed. Except for Om46 and Om67, which formed a distinct clade, phylogenetic analysis showed that most of the study strains grouped together, with some subgroups forming according to genetic constellation, geographic location, and date of isolation. The high potential of G9 strains to generate different P and G serotype combinations through reassortment suggests that it will be important to determine if current vaccines provide heterotypic protection against these strains and underscores the need for continued surveillance for G9 and other unusual or emerging rotavirus strains.