nsp2

SARS-CoV nsp2 is a counterpart of the p65 protein of MHV. As with nsp1, sequence homology is very low and does not permit confident sequence alignment. In MHV p65 has spatially different membrane localization from nsp1 and co-localizes with the MHV homologue of SARS nsp8. In MHV, p65 plays an important role in the viral life cycle that appears to be distinct from that of its counterparts in other coronaviruses. Based on immunolocalization studies in MHV, p65 may  function in concert with counterparts of SARS nsp1, 5, 7, 8, 9, 10, 12, 13 and sars9a. Deletion mutagenesis with infectious clones of SARS and MHV indicated that nsp2 is dispensable for viral replication in cell culture; however, deletion of the nsp2 coding sequence attenuates viral growth and RNA synthesis. The exact nature of the role of nsp2 in the context of viral growth and RNA synthesis is still not clear.

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