Humoral response of Meriones libycus to experimental infection with Leishmania major

The humoral responses of laboratory-reared jirds (Meriones libycus) to inoc ulation with various doses of Leishmania major were determined. The animals were inoculated intradermally with 10(2), 10(3), 10(5) or 10(7) promastigo tes of a strain of L. major originally isolated from a Jordanian patient. T he jirds were then bled at various intervals throughout the 26 weeks of the study, and the sera checked, by IFAT, for antibodies to homologous parasit es. There were no detectable humoral responses in the animals inoculated wi th 10(2) promastigotes each or in parasite-free controls but a positive res ponse was apparent in each of the other jirds. The animals given 10(3) prom astigotes each required 3 months to become IFAT-positive whereas those give n 10(5) and 10(7) parasites only needed 4 and 2 weeks, respectively. More t han 50% of the animals inoculated with 10(3) parasites each developed stron gly positive sera 2 months post-infection, whereas > 50% of the animals ino culated with 10(5) or 10(7) parasites each had strongly or very strongly po sitive sera 4 and 2 weeks post-inoculation, respectively. The data indicate that, in M. libycus inoculated with L. major, the time required for the hu moral response to develop and its intensity are both dose-related.