RODENT PLASMODIUM: POPULATION DYNAMICS OF EARLY SPOROGONY WITHIN ANOPHELES STEPHENSI MOSQUITOES.
June 27th, 2008 | by admin |RODENT PLASMODIUM: POPULATION DYNAMICS OF EARLY SPOROGONY WITHIN ANOPHELES STEPHENSI MOSQUITOES.
Early sporogony of Plasmodium parasites involves 2 major developmental transitions within the insect vector - gametocyte-to-ookinete and ookinete-to-oocyst. This study compared the population dynamics of early sporogony among murine rodent Plasmodium (P. berghei, P. chabaudi, P. vinckei and P. yoelii) developing within Anopheles stephensi mosquitoes. Estimates of absolute densities were determined for gametocytes, ookinetes and oocysts for 108 experimental infections. Total losses throughout early sporogony were greatest in P. vinckei (ca. 250,000-fold loss), followed by P. yoelii (ca. 70,000-fold loss), P. berghei (ca. 45,000-fold loss), and P. chabaudi (ca. 15,000-fold loss). The gametocyte-to-ookinete transition represented the most severe population bottleneck. Numerical losses during this transition (ca. 3,000 to 30,000-fold, depending on species) were orders of magnitude greater than losses incurred during the ookinete-to-oocyst transition (3 to 14-fold). There were no significant correlations between gametocyte and ookinete densities. Significant correlations between ookinete and oocyst densities existed for P. berghei, P. chabaudi and P. yoelii, but not for P. vinckei and were best described by nonlinear functions (P. berghei=sigmoid, P. chabaudi=hyperbolic, P. yoelii=sigmoid), indicating that ookinete development was density dependent. The upper theoretical limit for oocyst density on the mosquito midgut was greater for P. chabaudi and P. yoelii (ca. 300 oocysts per midgut) than for P. berghei (ca. 30 oocysts per midgut). This study provides basic information about population processes that occur during the early sporogonic development of some common laboratory model systems of malaria.
Poudel S, Newman R, Vaughan J.