MOLECULAR EPIDEMIOLOGY OF HUMAN ROTAVIRUSES IN SANTIAGO, CHILE

Background. Protective immunity against rotavirus infection is directe d against antigenic epitopes on the outer capsid proteins VP7 and VP4. Our aim was to characterize the epidemiology of rotavirus antigenic t ypes over time in Santiago, Chile. Methods. We prospectively obtained 2097 stool samples for rotavirus testing, VP7 (G1 to G4) and VP4 (P4, P6, P8, P9) typing from children with diarrhea evaluated in emergency rooms of 5 base hospitals of Santiago. In addition 256 rotavirus-posit ive samples collected between 1985 and 1987 in the north health care a rea of Santiago were studied, Results. Of 995 rotavirus-positive sampl es obtained 825 (82%) were typable for 1 or more VP7 types. G1 represe nted 81% of the G-typed samples during 1993 through 1995 and 77% durin g 1985 through 1987, predominating in all health care areas. G2 was ne xt most common in all 5 areas, representing 6 to 23% of typed samples, with 1 area, the Southeast concentrating a significantly higher numbe r of G2 infections. G2 declined from 35% of rotavirus-positive samples in 1993 to 0% in 1995 (P < 0.001), and from 25% to 2% in the north he alth care area from 1985 to 1987 (P < 0.001). G4 was uncommon and sign ificantly more prevalent in 1985 through 1987 than in 1993 through 199 5 (7% vs. 3%, P = 0.015). G3 was not detected, G1P8 (53%) and G2P4 (16 %) combinations were by far the most commonly detected G-P association s. Conclusions. In Santiago, Chile, rotavirus antigenic type G1P8 has been highly prevalent and G2P4 has circulated in cycles. Differences i n epidemiology of rotavirus antigenic types worldwide may prove to be relevant in efficacy of rotavirus vaccines.