Evolución de la infección en cobayos infectados con la variante atenuada XJO del virus Junín / [Development of the infection in guinea pigs infected with the attenuated variant XJO of Junín virus]

As previously shown, the XJO variant of Junin virus (JV) is attenuated and elicits in guinea pigs a lasting humoral response and resistance to the challenge with XJ pathogenic strain, during at least three months. In this paper the long term evolution of guinea pigs inoculated with XJO by im route was studied. Ten animals were infected with 10(3) PFU of XJO at day 0 (group I) and an other 10, at days 0 and 77 (group II). Another 30 guinea pigs were inoculated with 10(2) PFU at day 0 (group III) and 30 at days 0 and 12 (group IV). The animals were observed during 12 months. Circulating complement fixing (CF) and neutralizing (Nt) antibodies were measured at different periods pi in all groups, and lots of four guinea pigs from groups III and IV were challenged with 10(2) PFU of XJ strain at 120, 180, 240 and 360 days pi. Independently of the number of inoculations, the humoral response was similar in the four groups. CF antibodies appeared in all animals around 30 days pi in low values (1:4-1:8) and after a peak, which in a few animals reached 1:32-1:64, returned to previous levels by 12 months pi. Nt antibodies, first detected 15-20 days pi, reached maximum titers by 75-80 days pi, decreasing afterwards to a plateau which persisted throughout the 12 month period (Fig. 1A-B). Probably the continuous presence of antibodies could account for the 100

resistance to the challenge with XJ pathogenic strain shown by these animals (table I).(ABSTRACT TRUNCATED AT 250 WORDS)