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Special Issue Article
EXPERIMENTAL MODELS FOR LABORATORY MALARIA RESEARCH
The study of malaria parasites may be broadly divided into two major disciplines; those that involve observation of human malaria parasites in their natural hosts in endemic areas, and those that rely on experimental manipulation of living parasites in the laboratory. The latter type of study involves either the manipulation of human malaria parasites, most commonly Plasmodium falciparum, in in vitro cultures of human blood or (uncommonly) in a permissible animal host, or the use of non-human malaria parasites in laboratory animals. Depending on the scope and purpose of the experiments, there will be advantages and disadvantages associated with each particular approach. When the aim of the laboratory scientist is to model most closely the natural situation of the malaria parasite, it is apparent that in vitro culture will often be far from satisfactory, as the physiological conditions in the blood of a living animal cannot be replicated accurately in a culture flask. Indeed, as the intricate interplay and vital association between Plasmodium and its host is fundamental to much of the biology of the malaria parasite, so removing it from the natural host will drastically alter its biology. That is not to say, of course, that in vitro studies are without merit, as they have been hugely important in informing a great deal regarding the biology of malaria parasites. But for certain types of studies, such as those that rely on maintenance of the whole life cycle of the parasites, and particularly those studies concerned with host-parasite interactions, there can be no satisfactory alternative to the use of non-human parasites in experimental animals.
Animal malaria parasite studies are not without their disadvantages and limitations. Some of the laboratory host-parasite combinations, such as the rodent malaria parasites and their Mus musculus hosts do not occur in nature, and so, as in the culture flask, the parasites find themselves in an environment somewhat removed from that in which they evolved. Furthermore, there are serious and profound ethical questions to be taken into consideration with the use of animals in any scientific research. Finally, non-human malaria parasites, although often sharing considerable biological and genetic similarity to their human counterparts, do differ from the human parasites in...