Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 31. (Budapest, 1998)
A 24,000 g sediment of Plasmodium berghei induces IL-1 response in mice and exhibits protection against malaria infection Javed Agrewala UPMA 1 and H. S. BANYAL 2 l IMTECH, Chandigarh, 160014, India Department of Zoobgy, Panjab University, Chandigarh, 160014, India (Received February 25,1998) Abstract'.Plasmodium berghei was subjected to differential centrifugádon. Mice immunized with sediments (SI and SHI) emulsified in Freund's complete adjuvant (FCA) and challenged with 1 x 10 live P. berghei showed that SIII imparted complete protection against infection. SIII with FCA or saponin adjuvants showed the latter to be a better adjuvant as postchallenge parasitaemia in mice remained below 2%. Immune sera obtained from the Slll-saponin group inhibited 89% merozoite invasion in vitro. High antibody level was detected by indirect immunofluorescence assay (IFA). Sera collected from S-III immunized mice showed enhanced level of IL-I. Biochemical analysis of sediments revealed SIII to be enriched in acid proteinase and acid phosphatase. The role of parasite component sedimented at 24,000 g in malaria protection is discussed. Key words: Plasmodium berghei, malaria, in vitro, IL-I, saponin INTRODUCTION Clinical-manifestations of malaria are mainly due to blood stages of Plasmodium. Merozoite invades the host's erythrocyte and propagates intracellularly by utilizing host cell haemoglobin (Pasvol and Wilson 1982). Invagination of red cell membrane is mediated by contents of rhoptries emptied during the process of invasion (Bannister et al. 1986). A high molecular weight protein present in the rhoptry of P. yoelii exhibited protective immunity (Holder and Freeman 1981). The rhoptry content involved in invasion process may be analogous to the proteases of parasite since a 68 kDa neutral endopeptidase of P. berghei has been associated with the apical complex of the merozoite (Bernard and Schrevel 1987). Studies with protease inhibitors have also suggested a definite role of malarial proteases in the invasion process (Banyai et al. 1981; Hadley et al. 1983). Proteases degrade host cell haemoglobin and are present in lysosomal organelles in Plasmodium (Vander Jagt et al. 1992). Sephadex purified malarial proteases partially protect mice against P. berghei (Makkar et al. 1995).
