Discovery of a second form of tripartite complex containing gH-gL of human herpesvirus 6 and observations on CD46.
The human herpesvirus 6 (HHV-6) glycoprotein H (gH)-glycoprotein L (gL) complex associates with glycoprotein Q (gQ) (Y. Mori, P. Akkapaiboon, X. Yang, and K. Yamanishi, J. Virol. 77:2452-2458, 2003), and the gH-gL-gQ complex interacts with human CD46 (Y. Mori, X. Yang, P. Akkapaiboon, T. Okuno, and K. Yamanishi, J. Virol. 77:4992-4999, 2003). Here, we show that the HHV-6 U47 gene, which is a positional homolog of the human cytomegalovirus glycoprotein O (gO) gene, encodes a third component of the HHV-6 gH-gL-containing envelope complex. A monoclonal antibody (MAb) against the amino terminus of HHV-6 gO reacted in immunoblots with protein species migrating at 120 to 130 kDa and 74 to 80 kDa in lysates of HHV-6-infected cells and with a 74- to 80-kDa protein species in purified virions. The 80-kDa form of gO was coimmunoprecipitated with an anti-gH MAb, but an anti-gQ MAb, which coimmunoprecipitated gH, did not coprecipitate gO. Furthermore, the gH-gL-gO complex did not bind to human CD46, indicating that the complex was not a ligand for CD46. These findings suggested that the viral envelope contains at least two kinds of tripartite complexes, gH-gL-gQ and gH-gL-gO, and that the gH-gL-gO complex may play a role different from that of gH-gL-gQ during viral infection. This is the first report of two kinds of gH-gL complexes on the viral envelope in a member of the herpesvirus family.
Mori
Yasuko
Y
Department of Microbiology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan. ymori@micro.med.osaka-u.ac.jp
Akkapaiboon
Pilailuk
P
Yonemoto
Sayoko
S
Koike
Masato
M
Takemoto
Masaya
M
Sadaoka
Tomohiko
T
Sasamoto
Yumi
Y
Konishi
Shozo
S
Uchiyama
Yasuo
Y
Yamanishi
Koichi
K
D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000378:metabolism*; D002460:Cell Line; D015654:Herpesvirus 6, Human / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013601:T-Lymphocytes / Q000821:virology; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D015703:Antigens, CD; C497857:CD46 protein, human; D008024:Ligands; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; C077407:glycoprotein L, Human herpesvirus 1; C439068:glycoprotein O, cytomegalovirus; C070917:glycoprotein H, herpesvirus 6