Antibody isotype responses in infection and co-infection with Nippostrongylus brasiliensis and malaria. Mice were infected with 200 Nb L3 larvae and/or 105 Pcc-infected RBCs on day 0. Serum antibody titres (A) IgG1 (B) IgG2a to recombinant Pcc antigen MSP-119 (i), crude Pcc antigen (pRBC) (ii) and crude Nb antigen (NbA) (iii) were measured at day 20 post-infection for 8 mice per infection group. Black bars represent the Pcc mice, white bars the Nb mice and the chequered bars the co-infected mice (Pcc-Nb). Antibody titres are shown on the y-axis 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 a 1/200 dilution. The letter X highlights those responses that are cross-reactive. Groups not connected by the same letter denote pairs that are significantly different according to Tukey's Pairwise analysis.