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closeRelationship between numbers of oocysts and salivary gland sporozoites
Posted by Vanderberg on 14 Mar 2008 at 20:33 GMT
The relationship between numbers of oocysts and numbers of salivary gland sporozoites that the authors have shown is reminiscent of our "ancient" results with Plasmodium berghei. When we first developed a laboratory system for completing development of this parasite in mosquitoes, we used Anopheles quadrimaculatus as the vector. We later switched to An. stephensi (Yoeli, Vanderberg, Nawrot and Most. 1965. Studies on sporozoite-induced infections of rodent malaria. II. Anopheles stephensi as an experimental vector of Plasmodium berghei. Amer. J. Trop. Med. Hyg. 14: 927-930.) We had found that many more oocysts were being produced in An. quadrimaculatus but that this translated into fewer salivary gland sporozoites. We postulated a "crowding" effect that limited the further development of oocysts when there were "too many" within a given mosquito. This appears similar to the saturating function that the authors have shown in Fig. 4B. (Of course, in our case, one could not exclude the possibility of differences between the salivary glands of these two species of mosquito.) This kind of "unglamorous" study presented by these authors may be of great importance in understanding the dynamics of transmission-blocking immunity. It is conceivable that simply reducing oocyst numbers might end up enhancing transmission of sporozoites.