A rotavirus sample collection from 19 consecutive years was used to investigate the heterogeneity and the dynamics of evolution of G1 rotavirus strains in a geographically defined population. Phylogenetic analysis of the VP7 gene sequences of G1P[8] human rotavirus strains showed the circulation of a heterogeneous population comprising three lineages and seven sublineages. Increases in the circulation of G1 rotaviruses were apparently associated with the introduction of novel G1 strains that exhibited multiple amino acid changes in antigenic regions involved in rotavirus neutralization compared to the strains circulating in the previous years. The emergence and/or introduction of G1 antigenic variants might be responsible for the continuous circulation of G1 rotaviruses in the local population, with the various lineages and sublineages appearing, disappearing, or cocirculating in an alternate fashion under the influence of immune-pressure mechanisms. Sequence analysis of VP4-encoding genes of the G1 strains revealed that the older strains were associated with a unique VP4 lineage, while a novel VP4 lineage emerged after 1995. The introduction of human rotavirus vaccines might alter the forces and balances that drive rotavirus evolution and determine the spread of novel strains that are antigenically different from those included in the vaccine formulations. The continuous emergence of VP7-VP4 gene combinations in human rotavirus strains should be taken into consideration when devising vaccination strategies.

Infection by an animal-like strain of rotavirus (PA260/97) was diagnosed in a child with gastroenteritis in Palermo, Italy, in 1997. Sequence analysis of VP7, VP4, VP6, and NSP4 genes showed resemblance to a G3P[3] canine strain identified in Italy in 1996. Dogs are a potential source of human viral pathogens.

Noroviruses were detected in 48.4% of 192 children (<3 years of age) hospitalized for gastroenteritis in Palermo, Italy, during 2004; predominant genotypes were GGIIb/Hilversum and GGII.4 Hunter. Of children with viral enteritis, 19.6% had a mixed norovirus-rotavirus infection. The severity of infection was lower for norovirus than for rotavirus but increased in co-infection.

No abstract

Three G3P[9] rotaviruses, detected in children hospitalized with gastroenteritis in Palermo, Italy, were found to be genetically related to strains of either human or feline origin in the VP7, VP4, and VP6 genes. In contrast, in the NSP4 gene the viruses resembled G2P[4] human strains, suggesting a reassortment between AU-1-like and Kun-like strains.Group A rotaviruses are a major cause of acute gastroenteritis in humans and animals (14). The rotavirus genome is composed of 11 segments of double-stranded RNA (dsRNA) (4). The pattern of migration of the dsRNA by polyacrylamide gel electrophoresis (PAGE) allows the distinction of a long, short, or supershort electropherotype (e-type) (4). The viruses are classified as G and P types on the basis of the outer capsid proteins VP7 and VP4, respectively (4). Of the 15 G types and the 27 P types, 5 G types (types G1 to G4 and G9) and three P types (types P[4], P[6], and P[8]) appear to be common in human rotaviruses (21). On the basis of their reactivities to VP6-specific monoclonal antibodies, group A rotaviruses are classified into types SGI, SGII, SGI ϩ SGII, and SG-non I-non II (4). The majority of SGI and SGII animal rotavirus strains and SGII human rotavirus strains display a long e-type of migration of the 11 dsRNA gene segments, while almost all SGI human rotaviruses possess a short e-type (14). The nonstructural protein NSP4 is able to induce diarrhea in experimental rodents through a Ca 2ϩ -dependent signaling pathway (18). Passively acquired antibodies to NSP4 appear to prevent watery diarrhea in mice (2), and this sets NSP4 as a potential vaccine target. Six NSP4 genotypes (genotypes A to F) have been established in group A rotaviruses. In humans, NSP4 genotypes A (Kun-like) and B (Wa-like) are common. Genotype C (AU-1-like) is common in feline and canine strains but is infrequent in human rotaviruses (3).The G3 VP7 specificity has been identified in rotavirus strains from almost all susceptible animal species (4). In humans, G3 rotaviruses are usually associated with the P[8] VP4 genotype and, more rarely, with the P[9] genotype (10,15,21). Conversely, the G3P[9] combination is common in feline rotaviruses (11). Interspecies infections between animals and humans can be revealed by the detection of strains with unexpected antigenic and genetic features. The first human G3P [9] rotavirus strain, strain AU-1, was isolated in Israel in 1982. The strain displayed animal-like features (a long e-type in conjunction with SGI specificity) and was shown by RNA-RNA hybridization to be closely related to feline rotaviruses (19).Uninterrupted surveillance activity for rotaviruses has been conducted in Palermo, Italy, since the mid-1980s. Between 1985 and 2005, 1,547 rotavirus-positive samples were collected and characterized either antigenically or genetically to predict the VP7, VP4, and VP6 specificities and the genome pattern. Three strains (strains PAF96/94, PAH136/96, and PAI58/96) displayed animal strain-like features, since they possessed a long e-type by PAGE an...

Noroviruses (NoVs) are important enteric pathogens of humans. Although they exhibit an impressive genetic diversity, few NoV strains appear to predominate worldwide. Limited epidemiological data are available on NoV gastroenteritis in Italy. In this study, we assessed the prevalence of human NoV in Italian children with gastroenteritis by using a reverse-transcription nested polymerase chain reaction (RT-PCR) assay specific for the RNA-dependent RNA polymerase (RdRp) on faecal samples collected throughout the 2004 surveillance activity in Palermo, Italy. NoVs were detected in 47% of the stool samples obtained from children <5 years age, admitted to hospital with acute non-bacterial gastroenteritis. A selection of strains was further analyzed by partial sequence analysis of the RdRp gene. The strains were characterized as genogroup (GG) II and clustered into two distinct virus populations that resembled the emerging European GGIIb/Hilversum strains and the Australian Hunter GGII.4 strains. A temporal pattern of distribution of the two NoV strains was observed which was consistent with an independent circulation of two separate strains in the local population. Based on this 1-year study we concluded that NoVs were a diffuse cause of sporadic cases of acute childhood gastroenteritis and that strains of global epidemiological relevance were circulating in Palermo, Italy in 2004.

Although the genetic/antigenic heterogeneity of human noroviruses (NoVs) is impressive, a few genogroup II strains of genotype 4 (GII.4) are dominant worldwide. GII.4 NoVs evolve rapidly and in the last 15 years six epidemic variants have been identified. In 2005–2006, surveillance of sporadic viral gastroenteritis in children in Palermo, Italy, resulted in the detection of NoV\ud strains in 20.9% of the patients admitted to\ud hospital. By restriction fragment length polymorphism (RFLP) and sequence analysis of\ud region A in the RNA-dependent RNA-polymerase\ud (RdRp) gene, 59 NoV strains were successfully\ud characterized. Eighty-one percent of the strains were characterized as GII.4, 14% as GIIb/Hilversum and 5% as GI.1. Phylogenetic analysis of region A and of the ORF1/ORF2 overlapping region of the GII.4 strains recovered in Palermo in the years 2002–2006 revealed the sequential emergence of four variants, GII.4 2002, 2004, 2006a, and 2006b. The variant GII.4 2006a was detected in June and July, 2006, while the variant\ud 2006b first appeared in August, 2006, becoming predominant thereafter. Based on these findings, the dynamics of replacement and circulation of the GII.4 NoV variants in Italy in 2005–2006 appear to have matched the temporal pattern observed in Europe during the same period

Rotavirus infection was detected in 39.9% of 1030 children hospitalized with gastroenteritis in Palermo, Italy, in the period 2001-2005. Rotavirus strains belonging to G1, G4 and G9 types were continually detected, with G1 being the most common type in 2001, 2002 and 2004. A G4 epidemic occurred in 2003, while G9 was predominant in 2005. G2 strains displayed a low prevalence, except in 2003. G3 rotaviruses accounted for 2.7-17% of the gastroenteritis episodes in 2002-2005. The P-type of a subset of 166 strains confirmed the circulation of the usual G/P combinations, but single G1P[6], G9P[9] and G6P[9] strains were also found.