Molecular epidemiology of norovirus strains in Paraguayan children during 2004-2005: description of a possible new GII.4 cluster.
BACKGROUND
Noroviruses (NoV) have been shown to be an important cause of morbidity and mortality in children worldwide, only second after Group A rotaviruses (RVA). In Paraguay, acute gastroenteritis (AGE) is the third cause of mortality in children ≤5 years old.


OBJECTIVE
To analyze the presence and diversity of NoV in Paraguayan children ≤5 years old presenting AGE.


METHODS
Three hundred seventy eight fecal samples, negative for pathogenic bacteria and RVA, were collected from children admitted as ambulatory and hospitalized patients in a large private hospital from Asuncion, Paraguay from 2004 to 2005. The presence and diversity of NoV was determined by two different RT-PCR strategies and nucleotide sequencing.


RESULTS
One hundred and sixty one samples were positive for NoV by partial amplification of the viral polymerase gene (RdRp). No seasonality or differences in the viral prevalence for the different age-groups were detected. GII and GI NoVs were associated to 58% and 42% of the infections, respectively. The genotype was determined in 18% (29/161) NoV-positive samples. The genotypes detected were: GII.4 (18%), GII.17 (18%), GII.6 (14%), GII.7 (14%), GII.3 (10%), GII.5 (3%), GII.8 (3%), GII.16 (3%), GI.3 (14%) and GI.8 (3%). Amplification of the ORF2 from the GII.4 strains showed the presence of a new GII.4 variant.


CONCLUSIONS
The results showed a continuous circulation of NoV in children throughout the two years of study and an extensive diversity of genotypes co-circulating, highlighting the need for better surveillance of NoV in Paraguayan children.
Laboratory of Comparative and Environmental Virology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Ministry of Health, Rio de Janeiro, RJ, Brazil; Molecular Biology and Genetics Department, Health Sciences Research Institute, National University of Asunción, Asunción, Paraguay.
Maria Eugenia
ME
Galeano
Magaly
M
Martinez
Alberto A
AA
Amarilla
Graciela
G
Russomando
Marize Pereira
MP
Miagostovich
Gabriel I
GI
Parra
José Paulo
JP
Leite
D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology; D002675:Child, Preschool; D016000:Cluster Analysis; D005243:Feces / Q000821:virology; D005260:Female; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D029322:Norovirus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D010239:Paraguay / Q000453:epidemiology; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D012367:RNA, Viral
Acute gastroenteritis; GII.4 norovirus; Norovirus; Paraguayan children