부산대학교 도서관

The most severe form of malaria is caused by a parasitic organism called Plasmodium falciparum. The disease is transmitted to humans by a mosquito bite which introduces the parasite into the bloodstream. Infection then occurs as parasites invade the erythrocytes (red blood cells), where they mature, reproduce and rupture these cells. As this cycle is repeated, the disease becomes more intense. 111-K has been identified as an antigen which is produced as a reaction to the presence of P. falciparum. (An antigen is a substance which induces the formation of antibodies that are the basis of immunity.) This antigen has been found to appear in critical stages of the malarial infection and its DNA sequence has been determined. The precise function of 111-K antigen is still largely unknown, but preliminary studies indicate that it may be a proteinase. Proteinases, or protein enzymes, are critical in the life cycle of this parasite. The amino acid sequences of 111-K and a group of cysteine proteinases were compared and some similarities were found. (Proteins are composed of varying sequences of amino acids.) Active sites of the amino acids cysteine and histidine appear to correspond to a similar area in the 111-K antigen which suggests that the 111-K antigen may be a cysteine proteinase. Preliminary studies show that the presence of the 111-K antigen induces some immunity to malaria in monkeys. The use of a malarial proteinase specific to one or more of these critical enzymes might be effective in blocking the reproductive cycle of this parasite and could lead to the development of an effective vaccine for malaria.