Humoral response of Meriones libycus to experimental infection with Leishmania major

Abstract

The humoral responses of laboratory-reared jirds (Meriones libycus) to inoculation with various doses of Leishmania major were determined. The animals were inoculated intradermally with 10², 10³, 10⁵ or 10⁷ promastigotes of a strain of L. major originally isolated from a Jordanian patient. The jirds were then bled at various intervals throughout the 26 weeks of the study, and the sera checked, by IFAT, for antibodies to homologous parasites. There were no detectable humoral responses in the animals inoculated with 10² promastigotes each or in parasite-free controls but a positive response was apparent in each of the other jirds. The animals given 10³ promastigotes each required 3 months to become IFAT-positive whereas those given 10⁵ and 10⁷ parasites only needed 4 and 2 weeks, respectively. More than 50% of the animals inoculated with 10³ parasites each developed strongly positive sera 2 months post-infection, whereas > 50% of the animals inoculated with 10⁵ or 10⁷ parasites each had strongly or very strongly positive sera 4 and 2 weeks post-inoculation, respectively. The data indicate that, in M. libycus inoculated with L. major, the time required for the humoral response to develop and its intensity are both dose-related.