"On a neutral host-virus model with applications to HCMV"Eichhorn, RaphaelSome viruses including the widespread Human Cytomegalovirus (HCMV) are able to maintain a high level of genetic diversity within hosts and across the whole virus population even in relatively conserved genomic regions. However, if we model the frequencies of two competing virus types in a single host using an ordinary Moran model with rare mutations we would expect a decrease of diversity over time, eventually leading to the extinction of one virus type. Thus this approach is too simplistic: real viral populations may be influenced by not only viral reproduction and mutation but also other evolutionary forces including but not limited to host birth and death, recombination and interactions between hosts leading to reinfections. Previous research by Pokalyuk and Wakolbinger investigated such a model considering a single locus and assuming that viral reproduction within hosts is driven by balancing selection. They showed how under these forces a high level of genetic diversity can be maintained over time. We extend this model to finitely many loci, add recombination between loci, but assume neutral viral reproduction within hosts. We analyse in which parameter regime non-trivial within host viral diversity can be observed under rare mutation but with standing genetic variation and determine the asymptotic within host type frequency distribution. Based on these findings we fit our model to actual observed genotype frequencies from Austrian HCMV patients. We find that the neutral model describes the data surprisingly well. Joint work in progress with Cornelia Pokalyuk, Irene Görzer, Büsra Külekçi and Madlen Mollik. |
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