Antibody responses to protein epitopes in infection and co-infection with Nippostrongylus brasiliensis and malaria. The parasite antigens used in ELISA were pre-treated with periodate to disrupt carbohydrate epitopes, in order to determine if cross-reactive responses target the carbohydrate or protein moiety of an antigen. Mice were infected with 200 Nb L3 larvae and/or 105 Pcc-infected RBCs on day 0. Serum antibody titres (y-axis) were measured at day 20 post-infection for 8 mice per infection group and represent the reciprocal of the greatest dilution at which O.D was greater than the mean plus 3 standard deviations of the O.D values observed for control mouse sera at 1/200 dilution. Antibody isotypes (A) IgG1 (B) IgG2a (C) IgG3 to recombinant Pcc antigen MSP-119 (i), crude Pcc antigen (pRBC) (ii) and crude Nb antigen (NbA) (iii) before (-) and after (+) treatment with periodate are shown. Black bars represent Pcc mice, white bars the Nb mice and the chequered bars the co-infected (Pcc-Nb) mice. (*) denotes pairs which are significantly different according to Tukey's pairwise analysis.