Caenorhabditis elegans males and hermaphrodites differ in susceptibility upon Orsay virus infection

Individuals differ in their susceptibility upon viral infection as a result of a complex interplay between the individuals genetic background and the environment. The genetic background determines the sex of an organism and affects a large range of traits. Here we show that the sex of Caenorhabdtis elegans affects the susceptibility upon infection with the intestinal pathogen the Orsay virus. We noticed that outbred, mixed male and hermaphrodite populations showed a lower viral load than inbred, hermaphrodite populations. This result suggested that either the method of breeding or the sex of the nematodes in the population affected the viral load. Therefore, males and hermaphrodites were separately infected. Populations of infected males showed a larger number of failed infections than hermaphrodites that originated from the same plate. Moreover, preliminary results suggest that the mechanism may be genotype-dependent. As Orsay virus infects nematodes after ingestion the difference in viral susceptibility may be determined by a different food intake by males and hermaphrodites. Yet, the food intake as measured by grinder movements is similar in males and hermaphrodites. Currently we are also quantifying the volume of food taken in by the male and hermaphrodite nematodes in liquid to get a better estimation of food intake during the viral infection. Besides, we are investigating if differences in molecular networks between both sexes can alter the viral susceptibility by measuring the transcriptional response upon infection. In nature C. elegans males may benefit from a higher resistance towards viruses and possibly other intestinal pathogens that are counteracted by similar mechanisms. An ecological advantage like increased pathogen resistance might be important for males in a species that suffers from outbreeding depression.