Genetic association of murine susceptibility to Brugia malayi microfilaraemia.

The influence of host genetics on susceptibility of mice to Brugia malayi microfilariae and its possible mechanism were studied. There was a strain-association for duration and peak level of microfilaraemia: CBA/CaJ, C3H/HeJ, DBA/1J, AuSs/J and A.S.w/Sn had a short duration (3-5 days) and low parasitemia (19-26 parasites/100 microliters blood) compared to C57Br/cdJ, AKR/J, C57BL/6J, 129/J, BALB/cJ, DBA/2J, B10.D2/NSn, B10.D2/OSn and SJL/J (duration of 58-73 days, peak parasitaemia of 58-74 parasites/100 microliters blood). Relative resistance to microfilariae was not related to the H-2 complex as determined in studies of congenic C3H.B10 (H-2b) and B10.H-2k mice and their background strains. This trait was inherited in a dominant fashion and involved a single or small number of genes. Serum anti-microfilarial antibodies reached highest levels in strains with a long duration compared to those with a short duration of parasitaemia (geometric mean titres of 1:13450 vs 1:284). The distribution of 51Cr-labelled microfilariae among the livers, spleens, lungs and kidneys of a resistant (CBA/CaJ) and a susceptible (C57BL/6J) strain was similar. Transfer of immune lymphoid cells or sera between histocompatible (H-2k) resistant CBA/CaJ mice and susceptible C57Br/cdJ animals did not alter the duration of microfilaraemia.