Reemerging of G1P[8] Rotavirus strains in Buenos Aires, Argentina in the cold season of 2014

MANDILE M; LEWEZUK L; CALVENTE N; ARGÜELLES M; GLIKMANN G; CASTELLO AA

Goa

Congreso; 11th International Symposium on Double-Stranded RNA Viruses.; 2015

Introduction: Group A rotaviruses (RVA) are the most frequent etiological agents causing severe diarrhea in infants. It has been estimated that ≈453,000 children under 5 years of age die of rotavirus disease each yearworldwide but around 90% of these fatalities occur in poor regions. Since 2006, two RVA vaccines were licensed in many countries: RV1 (monovalent, G1P[8] live attenuated strain) and RV5 (pentavalent, humanbovinereassortant). Within the first years following vaccine introduction in national schedules, substantial declines in all-cause gastroenteritis hospitalization and even larger declines in rotavirus gastroenteritishospitalizations have been observed. Argentina was one of the last countries in America introducing rotavirus vaccination by incorporating RV1 since January 2015 in the National Immunization Schedule.Methods and Materials: RVA positive diarrhea samples collected in Buenos Aires (BsAs) from 2012 through 2014 were genotyped by RT-PCR. Selected samples were sequenced to gain insight on evolution of commonand globally emerging human RVA strains.Results and Discussion: In the present study we analyzed genotypes frequency and sequences of VP7 and VP4 genes from RVA strains causing severe gastroenteritis in children in BsAs in the last three years. Therehas been a sharp decline of previously highly prevalent G3P[8] and G2P[4] strains these three years. Notably, G12P[8] and G1P[8] strains were overwhelmingly dominant during 2013 and 2014 respectively with highpercentages (64% and 72% respectively). Of note, reemergence of G1 strains after four years of being almost undetectable was associated to increased incidence and highly severe cases with five fatalities reported in the Greater BsAs. In order to get insight in the origin and phylogenetic relationships of these viruses, we compared VP7 and VP4 sequences from current (2014) and previously circulating (2008-2010) G1P[8] strains from our collection and representative sequences from around the world. By phylogenetic analysis of VP7 gene we observed that the new Argentine strains clustered in the lineage I, while the strains belonging to previous periods grouped in the lineage II suggesting reintroduction during 2014.Conclusions: This recent increase in frequency of strains which are homotypic with the one formulated in the vaccine might open a favorable perspective. However, maintaining surveillance is necessary to verifyvaccine introduction effectiveness in Argentina. On the other hand, further characterization of highly virulent strains like the G1P[8] presented here is of primary interest and hence, sequencing of additionalgenes of several isolates are on the way.