Longitudinal humoral immune responses of Indian leaf monkey (Presbytis entellus) to Brugia malayi infection

Humoral immune responses of the Indian leaf monkey (Presbytis entellus) exp erimentally infected with Brugia malayi and exhibiting disease manifestatio ns were studied. Microfilaraemia, filaria-specific IgG and circulating immu ne complexes (CICs) were determined in the monkeys at different time-points after inoculation of B. malayi 3rd-stage larvae. Sera were analysed for re cognition pattern of adult parasite antigen molecules by immunoblotting. Mo re than 60 % of the infected monkeys developed episodic or persistent limb oedema with or without fever and with low or no microfilaraemia. While both CIC and filaria specific IgG levels were comparable in animals showing no disease symptoms (asymptomatics) and some animals showing symptoms (symptom atics), Ige levels peaked during pre-patent stage in symptomatics and durin g latent stage in asymptomatic animals. However, some of the symptomatic an imals showed a low level of filaria-specific IgG as compared to asymptomati c and other symptomatic animals. The immunoblot analysis showed non-reactiv ity of 17 and 55 kDa antigens with sera of symptomatic animals. The results thus suggest that humoral immune responses as measured in the present stud y do not precede the development of the manifestations. However, 2 non-reac tive antigen molecules identified by symptomatic sera need further study to establish their possible involvement, if any, in the development of acute disease manifestations in this model.