Insights to substrate binding and processing by West Nile Virus NS3 protease through combined modeling, protease mutagenesis, and kinetic studies

West Nile Virus is becoming a widespread pathogen, infecting people on at least four continents with no effective treatment for these infections or many of their associated pathologies. A key enzyme that is essential for viral replication is the viral protease NS2B-NS3, which is highly conserved among all flaviviruses. Using a combination of molecular fitting of substrates to the active site of the crystal structure of NS3,site-directed enzyme and cofactor mutagenesis, and kinetic studies on proteolytic processing of panels of short peptide substrates, we have identified important enzyme-substrate interactions that define substrate specificity for NS3 protease. In addition to better understanding the involvement of S2, S3, and S4 enzyme residues in substrate binding, a residue within cofactor NS2B has been found to strongly influence the preference of flavivirus proteases for lysine or arginine at P2 in substrates. Optimization of tetrapeptide substrates for enhanced protease affinity and processing efficiency has also provided important clues for developing inhibitors of West Nile Virus infection

Detection and Prevalence Patterns of Group I Coronaviruses in Bats, Northern Germany

The virus is probably maintained on the population level by amplification and transmission in maternity colonies

Evasion of influenza A viruses from innate and adaptive immune responses

The influenza A virus is one of the leading causes of respiratory tract infections in humans. Upon infection with an influenza A virus, both innate and adaptive immune responses are induced. Here we discuss various strategies used by influenza A viruses to evade innate immune responses and recognition by components of the humoral and cellular immune response, which consequently may result in reduced clearing of the virus and virus-infected cells. Finally, we discuss how the current knowledge about immune evasion can be used to improve influenza A vaccination strategies

Absence of viral envelope proteins in equine herpesvirus 1-infected blood mononuclear cells during cell-associated viremia.

&lt;p&gt;In vitro studies demonstrated that most equine herpesvirus 1 (EHV-1)-infected peripheral blood mononuclear cells (PBMC) do not expose viral envelope proteins on their surface. This protects them against antibody-dependent lysis. We examined whether viral envelope proteins are also undetectable on infected PBMC during cell-associated viremia. Further, surface expression of major histocompatibility complex (MHC)-I was examined, since MHC-I assists in making infected cells recognizable for cytotoxic T-lymphocytes (CTL). Four ponies, previously exposed to EHV, and two ponies that had no contact with EHV before, were inoculated with EHV-1. PBMC were collected at different time points up to 28 days post inoculation. Ninety-eight percent of the infected PBMC did not show viral envelope proteins on their surface. Moreover, infected PBMC without surface expression only produced immediate early and, at least, one early protein, ICP22, but not late envelope proteins gB and gM. This indicates that surface expression of viral envelope proteins is absent, simply because the PBMC are in an early phase of infection. The percentage of infected PBMC showing surface expression of MHC-I was similar as observed in non-infected PBMC from the same ponies (80-100%). Therefore, inefficient recognition of EHV-1-infected PBMC by CTLs does not arise from absent surface expression of MHC-I.&lt;/p&gt;</p