Epidemiological Surveillance of Group A Rotavirus in Children from Rural Areas in Argentina

VEGA C; RIVERO M; BADARACCO A; PARREÑO V

Praga

Encuentro; 17th Annual Meeting of the European Society for Clinical Virology; 2014

European Society for Clinical Virology

INTRODUCTION Rotaviruses are important enteric pathogens of humans and animals. Group A rotaviruses (RVAs) are a major public health problem in developing countries and human vaccines are now available. Rotavirus- associated enteritis is also a major problem in livestock, notably in young calves and piglets. The most frequent RVA strains detected in children worldwide are G1P[8], G2P[4], G3P[8], G4[P8] and G9P[8]. Due to the segmented nature of their genomes, RVA can exchange (reassort) genes during co-infections, a feature that is predicted to generate new, possibly moredangerous virus strains. In early epidemiological studies of RVA in humans, either sporadic cases or epidemics of atypical, animal-like RVA strains were described. In Argentina, farm animals are in close contact with humans, strengthening RVA chances of generating reassortant strains.  OBJECTIVE Our aim was to characterize RVA strains circulating in children from rural areas South of Buenos Aires province. MATERIALS Y METHODS A total of 210 pediatric patients with acute diarrhea were recruited for this study conducted between February 2006 and April 2008. Only patients with acute diarrhoea were recruited. To our knowledge, none of the patients had received RVA vaccine. Rotavirus was first detected by an in?house ELISA assay and RNA was extracted from RVA-positive samples. RT-PCR assay was performed and DNA sequences obtained were analyzed and compared. To our knowledge, none of the patients had received RVA vaccine. Rotavirus was first detected by an in?house ELISA assay and RNA was extracted from RVA-positive samples (está repetido). RT-PCR assay was performed for VP4, VP7 and VP6 genes and DNA sequences obtained were analyzed sequenced and compared. Neighbor-joining distance trees were constructed in MEGA6 using the aligned, partial sequences together with sequences from GenBank database. The evolutionary model applied was K2P. DISCUSION RVA was detected by ELISA assay in 10 fecal samples (4.75% detection rate). Watery diarrhea was observed in 86% of the RVA cases, while 88% of children showed abdominal pain and 67% experienced vomiting. Most of the cases (82%) occurred in winter and the average age of incidence was 27.8 months (SD: 26.9 months). Further genotype characterization was conducted by RT-PCR followed by nucleotide sequencing of G (VP7), P (VP4) and E (NSP4) genes. Of the 10 RVA positive samples, 60% belonged to G9P[8]E1 genotype, followed by 20% G2P[4]E2, 10% G1P[8]E1 and 10% G12P[8]E3. Interestingly, the Argentinean G12P[8]E3 strain belonged to Linage II of the G12 genotype, together with other samples from Argentina and Asia. The G9 samples also grouped with the other Argentinean, American and Asian samples in Lineage III of genotype G9. Reports from RVA strains circulating in the same area at this period of time showed a high incidence of G6P[5], G6P[11] and G10P[11]. No similarities were observed between the main RVA strains circulating in children and calves from South Buenos Aires province. Further surveillance studies are being conducted in rural areas of Argentina, where people live in close contact with farm animals, specially now that RVA vaccines are included in the National Immunization Program from Argentina.