Form and Function

B. malayi has an endosymbiont in it. An endosymbiont is an organism that lives within another organism, creating an endosymbiosis. It appears that B. malayi has evolved due to the presence of its bacterial endosymbiont Wolbachia. The adaptations appear to have created a mutualistic relationship between Brugia malayi and Wolbachia (Ghedin et al 2007).

Wolbachia lives in both male and female adult B. malayi, with many of them found in the female reproductive system. Wolbachia is widely found here in order to get a headstart on infecting the young, developing embryos (Slatko et al 2010).

Brugia malayi supplies amino acids to Wolbachia, and Wolbachia supplies many different nucleotides for B. malayi. Wolbachia is necessary for B. malayi to survive and reproduce (Foster et al 2005).

Without the adaptations to form a mutualistic relationship, Wolbachia would act as a parasite to Brugia malayi, taking its nutrients and leaving it with nothing.


Above image: A cross section of a female adult B. malayi. LC stands for lateral cord and O stands for ovary. The red coloring is the Wolbachia endosymbiont.


Form and Function
Because B. malayi have only longitudinal muscles, they move in an S shape motion. Female adults are 50mm on average, which is double the average of male adults (25mm) (Stanford 2008). This allows for the male to wrap around the female when they are ready for reproduction.

Above left image: microfilarial stage of Brugia malayi. Above right image: Cross section of Brugia species taken from a lymph node.

Two different forms of B. malayi can be found in the body. The first is considered the ‘periodic’ form because the microfilariae appear periodically in the blood stream. This form of the microfilariae are nocturnal and can usually be found from 10pm-2am. The second form of B. malayi is ‘subperiodic’ because the microfilariae are found in the blood of the host throughout the day (ADW 2003). Of course, periodic vs subperiodic means nothing when you've got a parasite floating around in your blood.

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