Amaratunga, C.Nandasiri, K.Weerasinghe, S.Manamperi, A.Longacre, S.Holm, I.Handunnetti, S.2016-11-222016-11-222000Proceedings of the New challenges in tropical medicine and parasitology - Oxford. 2000http://repository.kln.ac.lk/handle/123456789/15157Abstract - Proceedings of the New challenges in tropical medicine and parasitology - Oxford 2000, 18-22 September, Oxford, UK.In a pre-clinical trail of a vaccine against P.vivax malaria, toque monkeys were immunized with matalloaffinity-purified baculovirus-expressed. His-tagged recombinant Plasmodium cynomolgy ceylonensis (Pcc) C-terminal 19 kDa protiens of the major merozoite surface protein 1 (MSP1p19) with alum, under conditions acceptable for clinical trials. The P. cynomolgi-toque monkey system is highly analogous to P.vivax in humans. Eight animals were immunized with alum+MSP1p19 and 3 monkeys received alum alone. After four doses, the anti-MSP1p19 antibody titres of immunized animals reached 2.8x104. all animals were challenged with Pcc asexual blood stage parasites. The immunized animals showed significant, partial protection (p=0.0024). Four of these animals were given a second heterologous challenge infection of p.cynomolgi Gombak, (PcG) four months after the first challenge infection. Sequence analysis of PcG DNA revealed a single amino acid challenge differing from that of Pcc. The substitution which occurs at the nt 207 position in the C-terminal 19-kDa sequence changes the amino acid glutamate into lysine. Statistically significant protection was observed in the immunized animals (p=0.04), despite having a lower titre of antibodies at the time of re-challenge. This documents the ability of recombinant MSP1p19 with alum to protect against Pcc and PcG infections.en-USmalaria toque monkesArticle