Outbreaks of influenza A in humans, birds and animals constitute a continuous major threat to public health as influenza A viruses are capable of species shifts and enormous genetic variation. More than two decades ago, influenza entry was described to occur by endocytosis via clathrin-coated pits. Some evidence was also found for an alternative, clathrin-independent endocytic pathway, but it has not received attention until recently. I will focus on the novel, alternative process. Another virus becoming clinically more important, human cytomegalovirus (hCMV), can be detected in over 80% of the worlds population. Although most humans keep a latent infection without any symptoms, the virus can be reactivated in immuno-compromised individuals. Furthermore, severe mental defects as well as deafness can occur in case of congenital infection of newborns which is up to 1% of all newborns in the USA.
The endocytic entry mechanism of hCMV is largely unknown. Only recently specific integrin-subunits were identified as receptors. I propose to investigate the entry mechanism of hCMV in more detail. In general, the whole analysis will be carried out in a comparative manner to two already quite well studied model pathogens, namely simian virus 40 (SV40) and semliki forest virus (SFV). Experimentally, I will investigate the behaviour of individual, labelled viruses in and on cells using state of the art life-cell-imaging microscopy. I will set up screening assays for influenza A and hCMV infection applying siRNAs in a loss of function screen. Construction of stable cell lines harbouring a conditional RNAi / shRNA knockdown system targeting the clathrin-dependent uptake mechanism will enable me to separate the pathway from the parallel clathrin-dependent pathway.
These result s are expected to provide crucial information on endocytosis in general as well as reveal key steps in the entry process offering targets for antiviral therapy based on cellular factors.
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