Cytopathogenicity markers in the genome of Hungarian cytopathic isolates of bovine viral diarrhoea virus

The Molecular Biology of Pestiviruses

Pestiviruses are among the economically most important pathogens of livestock. The biology of these viruses is characterized by unique and interesting features that are both crucial for their success as pathogens and challenging from a scientific point of view. Elucidation of these features at the molecular level has made striking progress during recent years. The analyses revealed that major aspects of pestivirus biology show significant similarity to the biology of human hepatitis C virus (HCV). The detailed molecular analyses conducted for pestiviruses and HCV supported and complemented each other during the last three decades resulting in elucidation of the functions of viral proteins and RNA elements in replication and virus-host interaction. For pestiviruses, the analyses also helped to shed light on the molecular basis of persistent infection, a special strategy these viruses have evolved to be maintained within their host population. The results of these investigations are summarized in this chapter.

Complete genome sequences of a cytopathic/noncytopathic pair of border disease viruses

The complete genome sequences of a cytopathic/noncytopathic pair of border disease viruses (BDV) that were isolated from a sheep with mucosal disease-like lesions were determined. The cytopathic virus possessed an insert of 288 nucleotides that was derived from the Jiv cellular transcript and had 37 nucleotide differences from the noncytopathic virus.

Dengue virus NS4B interacts with NS3 and dissociates it from single-stranded RNA

Dengue virus, a member of the family Flaviviridae of positive-strand RNA viruses, has seven non-structural proteins: NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5. Except for enzymic activities contained within NS3 and NS5, the roles of the other proteins in virus replication and pathogenesis are not well defined. In this study, a physical interaction between NS4B and the helicase domain of NS3 was identified by using a yeast two-hybrid assay. This interaction was further confirmed by biochemical pull-down and immunoprecipitation assays, both with purified proteins and with dengue virus-infected cell lysates. NS4B co-localized with NS3 in the perinuclear region of infected human cells. Furthermore, NS4B dissociated NS3 from single-stranded RNA and consequently enhanced the helicase activity of NS3 in an in vitro unwinding assay. These results suggest that NS4B modulates dengue virus replication via its interaction with NS3.