Malaria Then and Now: Plasmodium spp. Selective Pressure and Alpha Globin Variation in Macaca fascicularis

Abstract

The interplay between gene frequencies and disease resistance has been documented in several human conditions. Hemaglobinopathies are especially well studied in humans, from sickle cell disease to alpha thalassemia. In this study, I examined the relation of gene frequency to disease resistance in the macaque malaria system. First, I examined the prevalence of Plasmodium spp. in Macaca fascicularis in Brunei, Southeast Asia, and then I looked at the genetic makeup at the alpha globin locus, which is implicated in malaria resistance. Prevalence of alpha globin variants and of malaria parasites in Brunei was compared to historical studies conducted throughout Southeast Asia. The results of this study suggest that despite the relaxation of malaria selection pressure in present-day Brunei, malaria has acted as a selective factor in macaques in the past. Additionally, a model whereby abnormal alpha globin in macaques does not confer a blood disorder disadvantage is explored. This study in M. fascicularis offers an important counterpoint to our knowledge of malaria resistance mechanisms in humans, and indicates that further investigations into non-human malaria systems are likely to provide key insights into the coevolution of hosts and their parasites.