Influenza B virus NS2, a nuclear export protein, directly associates with the viral ribonucleoprotein complex.
In Influenza A virus and Influenza B virus, the NS2 protein (nuclear export protein) has been proposed to mediate the nucleocytoplasmic trafficking of viral ribonucleoprotein (vRNP) by forming NS2-vRNP complexes. While the binding interactions of NS2 in these complexes have been well characterized for Influenza A virus, much less is known about Influenza B virus NS2 (B/NS2). In this report, we developed a specific antiserum against B/NS2 protein and demonstrated that B/NS2 was synthesized late in infection and packaged into virions after nucleocytoplasmic transport. Fractionation of detergent-disrupted virions in several conditions showed that B/NS2 remained associated with vRNP after separation of matrix protein M1 from vRNP, whereas Influenza A virus NS2 (A/NS2) was easily separated from vRNP and remained associated with M1, in accord with previous findings that A/NS2 associates with vRNP only through its binding of encapsidated M1. The results indicated that complex formation among vRNP, M1 and NS2 of Influenza B virus was different from that of Influenza A virus, and that B/NS2 associated with vRNP in the absence and presence of M1.
Imai
M
M
Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan.
Watanabe
S
S
Odagiri
T
T
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000276:immunology; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004285:Dogs; D006801:Humans; D009980:Influenza A virus / Q000378:metabolism; D009981:Influenza B virus / Q000378:metabolism*; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D012261:Ribonucleoproteins / Q000378:metabolism*; D014763:Viral Matrix Proteins / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D000914:Antibodies, Viral; D012261:Ribonucleoproteins; D014763:Viral Matrix Proteins; D017361:Viral Nonstructural Proteins