Author Archives: Ben Longdon

It is common to find considerable genetic variation in susceptibility to infection in natural populations. To investigate whether natural selection increases this variation we tested whether host populations show more genetic variation in susceptibility to pathogens that they naturally encounter than novel pathogens. Check out the paper in eLIFE here. In a large cross-infection experimentContinue reading “Host-pathogen coevolution increases genetic variation in susceptibility to infection”

Understanding the factors underlying host shifts is a major goal for infectious disease researchers. This effort has been further complicated by the fact that host-parasite interactions are now taking place in a period of unprecedented global climatic warming. We investigated how host shifts are affected by temperature by carrying out experimental infections using an RNAContinue reading “Changes in temperature alter susceptibility to a virus following a host shift”

Hosts shifts are more likely to occur between related host species and often rely on the pathogen evolving adaptations that increase their fitness in the novel host. We investigated how viruses evolve in different host species, by experimentally evolving replicate lineages of an RNA virus in 19 different host species that shared a common ancestorContinue reading “Virus evolution following host shifts”

There has been a four-fold increase in the number of known rhabdoviruses from 2010-2015, with rhabdoviruses being found in a diverse array of arthropods. In most cases we know nothing about the biology of these new viruses beyond the host they were isolated from. After using RNA-seq to indentify novel rhabdoviruses in Drosophilidae, we producedContinue reading “The evolution, diversity and host switching of rhabdoviruses”

Virulence — the harm a pathogen does to its host — can be extremely high following a host shift (for example HIV, SARs and Ebola), while other host shifts may go undetected as they cause few symptoms in the new host.  To examine how virulence changes following a host shift we carried out an experimentContinue reading “Changes in virulence following host shifts”

By carrying out a cross-infection experiment with 51 species of Drosophilidae and three sigma viruses (Figure 4) we found that the host phylogeny could explain most of the variation in viral replication and persistence between different host species. This effect is partly driven by viruses reaching a higher titre in those novel hosts most closelyContinue reading “Phylogenetic determinants of ability to infect novel host”

Emerging infectious diseases are often the result of a host shift, where a pathogen jumps from one host species to another. Host shifts appear to be common, with the phylogenies of hosts and pathogens often showing incongruence, suggesting parasites have switched between host species.  We became interested in host shifts following examining the phylogenies ofContinue reading “Host shifts”

We have found sigma viruses that infect several Drosophila species, Mediterranean fruit flies and a butterfly are all vertically transmitted (see here and here). Unlike bacterial symbionts, sigma viruses are transmitted vertically through both sperm and eggs, so are able to spread through populations despite being costly to infected flies. Four out of the five sigma virusesContinue reading “Vertical transmission and sweeps”

Sigma virus diversity One of the best-studied naturally occurring parasites of Drosophila is the sigma virus of Drosophila melanogaster (DMelSV). DMelSV is a negative sense single stranded RNA virus in the family Rhabdoviridae. DMelSV is particularly cool as it is transmitted purely vertically through both eggs and sperm, and also causes infected flies to becomeContinue reading “Sigma virus diversity”