Sequencing and Phylogenetic Analysis of Human Genotype P[6] Rotavirus Strains Detected in Hungary Provides Evidence for Genetic Heterogeneity within the P[6] VP4 Gene

Abstract

Although rotavirus genotype P[6] is one of the three most common VP4 specificities associated with human infection, the relatively few sequence data available in public databases suggest that the genetic variability within P[6] might be presently unexplored. Thus far, two human P[6] lineages (M37-like and AU19-like) and a single porcine P[6] lineage (Gottfried-like) have been identified by phylogenetic analysis. Serologic studies demonstrated that these three lineages are antigenically distinct from each other, a finding based on which they were classified into three subtypes, P2A[6] (M37-like), P2B[6] (Gottfried-like), and P2C[6] (AU19-like). To study heterogeneity within this genotype, we selected for molecular characterization a total of six P[6] strains detected during an ongoing surveillance in Hungary. The variable region of the VP4 gene was subjected to sequencing and phylogenetic analysis. Our data indicated that these six strains fell into two phylogenetic lineages distinguishable from the human lineages M37-like and AU19-like and from the porcine lineage Gottfried-like. Further studies are needed to understand whether these two novel lineages are genuine human strains or might have originated from animal strains and to evaluate the antigenic relationship of the novel Hungarian P[6] strains to the three established subtypes.Group A rotaviruses, members of the family Reoviridae, are the major cause of acute dehydrating gastroenteritis in children and young animals (7). The viral genome composed of 11 segments of double-stranded RNA is enclosed in a nonenveloped, icosahedral, triple-layered capsid. The outer capsid antigens, VP7 and VP4, carry the serotype and the genotype specificities and serve as a basis for the dual nomenclature. The specificities of VP7 are designated with a G (VP7 is a glycoprotein), while the specificities of VP4 are designated with a P (VP4 is a protease-sensitive protein). Based on nucleotide and deduced amino acid sequences, at least 15 G genotypes and 23 P genotypes have been established. Due to the lack of adequate immunological reagents (i.e., type-specific monoclonal antibodies or hyperimmune sera), some of the P genotypes have not been characterized serologically and a dual classification by P serotypes (designated with unbracketed numbers) and P genotypes (designated with bracketed numbers) is presently used for VP4 characterization. Out of 23 different P genotypes, only 14 P serotypes and 3 subtypes have been identified (7,14,21,23).Thus far, at least 10 G types (G1 to G6, G8 to G10, and G12) and 11 P types (P[1], P[3] to P[6], P[8] to P[11], P[14], and P[19]) have been identified in humans. Most of these specificities can also be found in animals, suggesting that certain human G and P types, especially those that are rarely detected, might have originated from animal strains either by direct interspecies transmission or by reassortment of cognate genes between heterologous and homologous strains. Serotypes G6 and G8, identified frequently in ruminants, or serotype G5, co...

Detection and Genotyping of Human Rotavirus VP4 and VP7 Genes by Reverse Transcriptase PCR and Reverse Hybridization

“…2) contained type-specific probes for P [4], P [6], P [8], P [9], and P [10]. Two probes were added to recognize the P [8] sequence present in the vaccine strain.…”

“…Since the VP4 and VP7 genes are independently segregated, different G and P combinations have been observed in natural infections. Based on global epidemiology data, G1P [8], G2P [4], G3P [8], G4P [8], G9P [6], and G9P [8] are the most prevalent genotypic combinations found in humans (21,44). Other genotypes are often found in animals, although transmission to humans is possible, and the spectrum of genotypes appearing in humans is increasing (15,27,30,31,38).…”

Identification of Group A Porcine Rotavirus Strains Bearing a Novel VP4 (P) Genotype in Italian Swine Herds

“…Along with cattle, pigs are regarded as important reservoirs for human rotavirus diversification, and there is evidence that heterologous rotaviruses of porcine origin or natural porcinehuman reassortants may have occurred and spread successfully throughout human populations on multiple occasions in Latin America, Southeast Asia, and Europe (1,3,5,12,16,19,24,33,37,42,43). The detection of a new rotavirus VP4 type extends our knowledge of the genetic/antigenic diversity of group A rotaviruses and highlights the need to attempt to type "nontypeable" rotavirus-positive samples.…”

Molecular Analysis of Nsp4 Coding Gene of Porcine Rotavirus in Brazil

“…In fact, pigs may serve as a reservoir of RVs for humans, as described by several authors in different countries, such as India, Ecuador and Hungary (BANYAI et al, 2004;VARGHESE et al, 2004;BANYAI et al, 2009). It has been proposed that human RVs Wa-like strains and swine strains have a common origin (MATTHIJNSSENS et al, 2008b), and, recently, a new virus isolated from pigs was closely related to a novel group of human rotaviruses (WAKUDA et al, 2011).…”

“…G11 rotaviruses were first detected in pigs in Mexico and Venezuela (RUIZ et al, 1988;CIARLET et al, 1994;ROSEN et al, 1994) and are believed to be circulating in this population, although in low numbers. In subsequent years, no additional G11 strains were detected in the same or nearby pig farms, but in the last decade, several reports have described the isolation of G11 RVs strains from humans .…”