Emergence in 2017-2019 of novel reassortant equine-like G3 rotavirus strains in Palermo, Sicily.

Rotavirus A (RVA) is a major etiologic agent of gastroenteritis in children worldwide. Hospital-based surveillance of viral gastroenteritis in paediatric population in Palermo (Italy) from 2017 onwards revealed a sharp increase in G3P[8] RVAs, accounting for 71% of all the RVAs detected in 2019. This pattern had not been observed before in Italy, with G3 RVA usually being detected at rates lower than 3%. In order to investigate this unique epidemiological pattern, the genetic diversity of G3 RVAs identified during a 16-year long surveillance (2004-2019) was explored by systematic sequencing of the VP7 and VP4 genes and by whole genome sequencing of selected G3 strains, representative of the various RVA seasons. Sequence and phylogenetic analyses of the VP7 and VP4 genes revealed the emergence, in 2017 of reassortant equine-like G3P[8], which gradually replaced former G3P[8] strains. The G3P[8] circulating before 2017 showed a Wa-like constellation of genome segments while the G3P[8] that emerged in 2017 had a DS-1-like backbone. On direct inspection of the VP7 and VP4 antigenic epitopes, the equine-like G3P[8] strains possessed several amino acid variations in neutralizing regions compared with vaccine strains. The equine-like G3P[8] RVAs are a further example of the zoonotic impact of animal viruses on human health.

Analysis of GII.P7 and GII.6 noroviruses circulating in Italy during 2011-2016 reveals a replacement of lineages and complex recombination history.

Noroviruses are important human enteric pathogens and monitoring their genetic diversity is important for epidemiological surveillance, vaccine development, and understanding of RNA viruses evolution. Epidemiological investigations have revealed that genogroup II, genotype 6 noroviruses (GII.6) are common agents of gastroenteritis. Upon sequencing of the ORF2 (encoding the viral capsid), GII.6 viruses have been distinguished into three variants. Sentinel hospital-based surveillance in Italy revealed that GII.6 noroviruses were the second most common capsid genotype in 2015, mostly in association with a GII.P7 ORF1 (encoding the viral polymerase). Upon molecular characterization of the ORF1 and ORF2, the GII.P7_GII.6 epidemic viruses circulating in 2014-2015 (variant GII.6b) were different from those that circulated sporadically in 2011-2013 (variant GII.6a). Analysis of the ORF1 (GII.P7) and ORF2 (GII.6) sequences available in the databases unveiled marked genetic diversity and peculiarities in the phylogenetic segregation patterns, suggesting multiple recombination events. Phylogenetic analyses suggest that recent GII.P7_GII.6b viruses were circulating as early as 2008, and formed a genetically homogenous group that emerged globally.

Molecular detection of canine bufaviruses in wild canids.

Novel protoparvoviruses genetically related to human and non-human primate bufaviruses (BuVs) have been detected recently in respiratory and enteric specimens collected from dogs and cats. In this study, by molecular screening of archival collections of faecal samples from wolves and foxes, we detected BuVs with a rate of 17.1% (7/41) and 10.5% (9/86), respectively. Sequence analysis of a portion of the ORF2 gene region of nine positive samples showed that the viruses in these samples were closely related to BuVs (97.5-99.0% nucleotide sequence identity) found in domestic carnivores.

Epidemiological dynamics of norovirus GII.4 variant New Orleans 2009.

Norovirus (NoV) is one of the major causes of diarrhoeal disease with epidemic, outbreak and sporadic patterns in humans of all ages worldwide. NoVs of genotype GII.4 cause nearly 80-90 % of all NoV infections in humans. Periodically, some GII.4 strains become predominant, generating major pandemic variants. Retrospective analysis of the GII.4 NoV strains detected in Italy between 2007 and 2013 indicated that the pandemic variant New Orleans 2009 emerged in Italy in the late 2009, became predominant in 2010-2011 and continued to circulate in a sporadic fashion until April 2013. Upon phylogenetic analysis based on the small diagnostic regions A and C, the late New Orleans 2009 NoVs circulating during 2011-2013 appeared to be genetically different from the early New Orleans 2009 strains that circulated in 2010. For a selection of strains, a 3.2 kb genome portion at the 3' end was sequenced. In the partial ORF1 and in the full-length ORF2 and ORF3, the 2011-2013 New Orleans NoVs comprised at least three distinct genetic subclusters. By comparison with sequences retrieved from the databases, these subclusters were also found to circulate globally, suggesting that the local circulation reflected repeated introductions of different strains, rather than local selection of novel viruses. Phylogenetic subclustering did not correlate with changes in residues located in predicted putative capsid epitopes, although several changes affected the P2 domain in epitopes A, C, D and E.

Evolution of DS-1-like human G2P[4] rotaviruses assessed by complete genome analyses.

Group A rotaviruses (RVAs) are a leading cause of viral gastroenteritis in children, with G2P[4] RVA being one of the most common human strains worldwide. The complete genome sequences of nine G2P[4] RVA strains, selected from a 26-year archival collection (1985-2011) established in Palermo, Italy, were determined. A strain associated with a peak of G2P[4] RVA activity in 1996 resembled a reassortant strain identified in Kenya in 1982 and differed completely in genomic make up from more recent strains that circulated during 2004-2011. Conversely, the 2004-2011 G2P[4] RVAs were genetically more similar to contemporary RVA strains circulating globally. Recent G2P[4] strains possessed either single or multiple genome segments (VP1, VP3 and/or NSP4) likely derived from ruminant viruses through intra-genotype reassortment. Amino acid substitutions were selected and maintained over time in the VP7 and VP8* antigenic proteins, allowing the circulation of two contemporary G2P[4] variants to be distinguished. Altogether, these findings suggest that major changes in the genomic composition of recent G2P[4] RVAs occurred in the early 2000s, leading to the appearance of a novel variant of the DS-1-like genotype constellation. Whether the modifications observed in the neutralizing antigens and in the genome composition of modern G2P[4] RVAs may affect the long-term effectiveness of the vaccination programmes remains to be explored.

Detection and characterization of canine astroviruses.

Astroviruses (AstVs) have been identified only occasionally in dogs. A canine AstV, strain Bari/08/ITA, was detected from a pup with gastroenteric signs and the virus was isolated in cell culture and characterized molecularly. In the full-length capsid protein, the virus displayed genetic similarities (83.5 % aa identity) to another canine AstV strain, although a high rate of variation occurred in the hypervariable domain, which is related to AstV antigenic specificity. Specific antibodies were detected in the convalescent dog, indicating seroconversion, and in 59 % of a collection of dog serum samples. Using primers specific for canine AstV, designed to detect a conserved region of ORF1b, canine AstVs were detected in 24.5 % of young pups with gastroenteritis, either alone or in mixed infections with other canine pathogens. In contrast, AstVs were detected in only 9.3 % of asymptomatic pups. These findings indicate that canine AstVs are common in dogs and may suggest a possible role as canine enteric pathogens.

Detection of a porcine-like rotavirus in a child with enteritis in Italy.

During a 1-year rotavirus surveillance of children hospitalized with acute gastroenteritis in Brescia Hospital, Italy, a chimerical rotavirus strain, G3P[6], was detected, displaying the VP7 and VP4 genes of porcine origin and the NSP4 and VP6 genes of human origin. The reassortant nature of the virus rules out a direct zoonotic event.