Human herpesvirus genetic diversity and host adaptation
Le 18 Juin 2021
11h30 - This seminar will be streamed live online
Manuela Sironi
Bioinformatics - Scientific Institute IRCCS E.MEDEA
Bosisio-Parini, Italy
Herpesviruses belong to a diverse family (Herpesviridae, order Herpesvirales) of enveloped, double-stranded DNA viruses that infect a wide range of animals and often establish life-long infections. In analogy to observations in other mammalian and non-mammalian hosts, herpesvirus infection is remarkably species-specific in primates, at least in natural settings. In line with these observations, the phylogenetic relationships among herpesviruses very often mirror those among their hosts, indicating that viral lineages frequently arose through co-speciation with host lineages. As a consequence, it is generally assumed that human herpesviruses originated in Africa and dispersed during early human migration events. However, our recent data indicated that this is not necessarily the case. For instance, extant VZV strains did not disperse from Africa, but from Europe, and HSV-2 circulating strains have relatively recent ancestry.
Some human herpesviruses such as HCMV display a remarkable species-specificity even in vitro - i.e., in the absence of the host adaptive immune response. This clearly implies that HCMV must have adapted to efficiently complete its infectious cycle in human cells. In line with this view, analyses of primate cytomegalovirus genomes indicated that core viral genes were targeted by positive selection during HCMV speciation. Some adaptive variants, though, were found to decrease replication in human cells, suggesting HCMV evolution towards viral temperance. Compared to HCMV, herpes simplex viruses have less strict species-specificity and cross-species transmission events have been described (often with very serious consequences for the non-natural host). In line with this view, genes involved in immune evasion were the major targets of selection during the adaptation of herpes simplex viruses to hominins. However, we have recently found that the evolution of ICP47 in HSV-1/HSV-2 led to the loss of an immunosuppressive effect, suggesting that simplexviruses finely tune the balance between immunosuppressive and immunostimulatory pathways to promote successful co-exisence with their primate hosts. In summary, evolutionary analyses of human herpesvirus extant diversity can provide relevant information on the dispersal and selective patterns of these extremely prevalent human pathogens
Link to seminar: https://umontpellier-fr.zoom.us/webinar/register/WN_kdKXfJ6tSSW2aRP_8orn6A
Recent publications related to the subject:
One year into the pandemic: Short-term evolution of SARS-CoV-2 and emergence of new lineages.
Infect Genet Evol. 2021 doi: 10.1016/j.meegid.2021.104869
Recent Out-of-Africa Migration of Human Herpes Simplex Viruses.
Mol Biol Evol. 2020 May doi: 10.1093/molbev/msaa001
Possible European Origin of Circulating Varicella Zoster Virus Strains.
J Infect Dis. 2020 Mar doi: 10.1093/infdis/jiz227
Contact:
Contact: ignacio.bravo@cnrs.fr
Contact du Comité SEEM: seem@services.cnrs.fr. Contact du Labex CEMEB: cemeb-gestion@umontpellier.fr
