Inability of Plasmodium knowlesi sporozoites to invade Anopheles freeborni salivary glands.

Oocysts of Plasmodium knowlesi developed normally on the gut of the mosquito Anopheles freeborni, rupturing and releasing sporozoites at 10-14 days post-infection. Subsequently, however, sporozoites were never found in this mosquito's salivary glands. Heterologous transplants of whole salivary glands from uninfected An. freeborni and An. dirus, a completely susceptible mosquito, into the abdomens of insects heavily infected with mature oocysts were done. Sporozoites failed to infect An. freeborni glands implanted in An. dirus but did enter An. dirus glands implanted in An. freeborni. These experiments suggest that P. knowlesi sporozoites are unable to recognize An. freeborni glands.