After excision of the protein band from a sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel and trypsin digestion, mass spectrometry identified two proteins: SEL1L and a hitherto uncharacterized protein . Based on its mobility by SDSPAGE and its ER localization, we named this protein ERp90. Since we identified both SEL1L and ERp90 from the same band of the EndoH-treated sample, a more detailed analysis necessitated the use of an ERp90 antibody. In this study we identify ERp90 as a new member of the PDI family and an interaction partner of the ERAD component ERFAD. Moreover, our preliminary data indicate that, like ERFAD, ERp90 can be crosslinked to a larger complex of proteins. At least certain of the bands in the two complexes immunoisolated with antibodies against ERFAD and ERp90, respectively, migrate at the same apparent molecular mass. Based on these finding we cannot rule out entirely that ERFAD and ERp90 interact indirectly through other components of this complex. However, since the interaction between the two proteins withstands re-IP and because other proteins were much less abundant in the precipitate, we currently favor the idea that the interaction is direct. The interaction between ERp90 and ERFAD strongly implies a functional link. This notion is reinforced by the presence of the two proteins in the same set of organisms. Since we did not succeed in performing siRNA-mediated knockdown experiments of ERp90 to study an involvement of ERp90 in ERAD, we can presently only speculate about the function of ERp90 in relation to ERFAD. While ERFAD likely catalyzes a redox reaction, ERp90 could recruit misfolded proteins to the complex by virtue of its redoxinactive thioredoxin-like domains. Substrates bound by the complex of ERFAD and ERp90 could then be delivered and handed over to SEL1L, a function resembling the one recently described for OS-9 and GRP94. Alternatively, ERFAD and ERp90 could work on substrates already bound by SEL1L or OS9, and potentially also assist the transfer of substrates from either of these proteins to a retrotranslocation channel. Finally, ERp90 could perform a CXXC-independent redox function, conceivably in collaboration with the redox-active ERFAD, through the conserved C664 or even the CX9C motif in the Trx2. Future work should allow us to distinguish between these various possibilities. Influenza severity is usually characterised by the case-fatality rate. There are major Vemurafenib problems with this measure as the denominator is difficult to ascertain, resulting in widely varying estimates for the same viral strain. Using the CFR to characterise severity ignores the burden of disease in the vast majority of individuals who have symptomatic influenza but do not die. Many millions of individuals were infected with the pandemic strain of influenza A/H1N1v in 2009, and it is likely that many more will be infected by related strains in the coming years.