Typing by polymerase chain reaction of buffalo rotaviruses isolated in Italy

Whole-genome analysis of a rare G15P[21] group A rotavirus detected at a dairy cattle farm

Group A rotaviruses (RVAs) are a major cause of severe enteritis in humans and animals. RVAs have been identified in several animal species and their genetic diversity, the segmented nature of their RNA genome and the ability to spill over from one species to another can generate new RVA strains. In this study, we investigated the genome constellations of an unusual, rare, bovine RVA strain, G15P[21], identified from a farm with neonatal diarrhoea of calves in 2006. In parallel, the genome constellations of other RVA strains with different G/P types identified from the same farm in the same time span (2006-2008) were analysed. The genome constellation of strain K53 was G15-P[21]-I2-R2-C2-M2-A13-N2-T9-E2-H3 and was similar, overall, to that of the other bovine RVA strains (G6/10-P[11]-I2-R2-C2-M2-A13-N2-T6-E2-H3) with the exception of the NSP3 segment (T9 vs T6). This study describes RVA genomes with different genotype combinations isolated at a farm and also contributes to the understanding of the diversity and evaluation of rotavirus in a global context.

Are human P[14] rotavirus strains the result of interspecies transmissions from sheep or other ungulates that belong to the mammalian order Artiodactyla?

A limited number of human G6P[14] rotavirus strains that cause gastroenteritis in humans have been isolated in Europe and Australia. The complete genome sequences were determined for five of these human strains--B10925-97 (isolated in Belgium in 1997), 111/05-27 (Italy, 2005), PA169 (Italy, 1987), MG6 (Australia, 1993), and Hun5 (Hungary, 1997)--and their genetic relatedness to animal rotavirus strains was evaluated by sequencing the complete genome of the sheep rotavirus OVR762 (G8P[14]; Spain, 2002), the guanaco (Lama guanicoe) rotavirus strains Arg/Chubut/99 and Arg/Río Negro/98 (G8P[14] and G8P[1], respectively; Argentina, 1999 and 1998), the sable antelope strain RC-18/08 (G6P[14]; South Africa, 2008), and the bovine rotavirus strain Arg/B383/98 (G15P[11]; Argentina, 1998). These analyses revealed an overall consensus genomic constellation (G6/G8)-P[14]-I2-(R2/R5)-C2-M2-(A3/A11)-N2-T6-(E2/E12)-H3, together with a few gene reassortments, and the phylogenetic analyses confirmed that the P[14] human strains evaluated in this study were closely related to rotavirus strains isolated from sheep, cattle, goats, guanacos, and antelopes and to rabbits (albeit to a lesser extent), suggesting that one (or more) of these animal species might be the source of the human G6P[14] strains. The main feature of the genotype and phylogenetic analyses was the close overall genomic relatedness between the five human G6P[14] rotavirus strains and the ovine and antelope rotavirus strains. Taken together, these data strongly suggest a common origin for the human P[14] strains and those of the even-toed ungulates belonging to the mammalian order Artiodactyla, with sheep probably playing a key role in the interspecies transmission responsible for the introduction of P[14] rotavirus strains into the human population.

Distribution of G (VP7) and P (VP4) genotypes in buffalo group A rotaviruses isolated in Southern Italy

Group A rotaviruses are established agents of disease in buffalo calves. Early epidemiological studies in Italian buffalo herds revealed the predominance of strains with G8 specificity and detected strains with the rare, RRV-like, VP4 P[3] genotype. To acquire additional information on the VP4 and VP7 specificities of buffalo rotaviruses, a total of 125 fecal samples were collected from buffalo calves affected with diarrhoea, in seven dairy farms in Southern Italy. Rotaviruses were detected in 21 samples (16.8%) by an immunochromatographic assay and by reverse transcription-PCR (RT-PCR). Analysis of the VP7 gene revealed that 57% (12 of 21) of the isolates were G6, 23.8% were G8 (5 of 21) and 19% (4 of 21) were G10. Analysis of the VP4 revealed that 71.4% (15 of 21) of the isolates were P[5] and that 28.6% (6 of 21) were P[1]. The most common combination of G and P types was P[5],G6 (57%), followed by P[1],G10 (19%), P[5],G8 (14%) and P[1],G8 (9.5%). While P[5],G6 rotaviruses are very common in Italian bovine herds, the antigenic combination P[1],G10 is unusual and presumably derives from reassortment between P[1] and G10 strains, that appear to be more frequent in buffaloes and bovines, respectively. The presence of bovine-like G and P serotypes suggests that in Italy the epidemiology of buffalo rotaviruses overlaps the epidemiology of bovine rotaviruses, presumably because of the strict species affinity and/or of the intermingled distribution over the same geographical areas of the buffalo and bovine herds.

Molecular analysis of the VP7, VP4, VP6, NSP4, and NSP5/6 genes of a buffalo rotavirus strain: identification of the rare P[3] rhesus rotavirus-like VP4 gene allele

We report the detection and molecular characterization of a rotavirus strain, 10733, isolated from the feces of a buffalo calf affected with diarrhea in Italy. Strain 10733 was classified as a P[3] rotavirus, as the VP8* trypsin cleavage product of the VP4 protein revealed a high amino acid identity (96.2%) with that of rhesus rotavirus strain RRV (P5B[3]), used as the recipient virus in the human-simian reassortant vaccine. Analysis of the VP7 gene product revealed that strain 10733 possessed G6 serotype specificity, a type common in ruminants, with an amino acid identity to G6 rotavirus strains ranging from 88 to 98%, to Venezuelan bovine strain BRV033, and Hungarian human strain Hun4. Phylogenetic analysis based on the VP7 gene of G6 rotaviruses identified at least four lineages and an apparent linkage between each lineage and the VP4 specificity, suggesting the occurrence of repeated interspecies transmissions and genetic reassortment events between ruminant and human rotaviruses. Moreover, strain 10733 displayed a bovine-like NSP4 and NSP5/6 and a subgroup I VP6 specificity, as well as a long electropherotype pattern. The detection of the rare P[3] genotype in ruminants provides additional evidence for the wide genetic and antigenic diversity of group A rotaviruses.