A mouse cell-adapted NS4B mutation attenuates West Nile virus RNA synthesis.
An adaptive mutation (E249G) within West Nile virus (WNV) NS4B gene was consistently recovered from replicon RNAs in C3H/He mouse cells. The E249G is located at the C-terminal tail of NS4B predicted to be on the cytoplasmic side of the endoplasmic reticulum membrane. The E249G substitution reduced replicon RNA synthesis. Compared with the wild-type NS4B, the E249G mutant protein exhibited a similar efficiency in evasion of interferon-beta response. Recombinant E249G virus exhibited smaller plaques, slower growth kinetics, and lower RNA synthesis than the wild-type virus in a host-dependent manner, with the greatest difference in rodent cells (C3H/He and BHK-21) and the least difference in mosquito cells (C3/36). Selection of revertants of E249G virus identified a second site mutation at residue 246, which could compensate for the low replication phenotype in cell culture. These results demonstrate that distinct residues within the C-terminal tail of flavivirus NS4B are critical for viral replication.
Puig-Basagoiti
Francesc
F
Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12208, USA.
Tilgner
Mark
M
Bennett
Corey J
CJ
Zhou
Yangsheng
Y
Muñoz-Jordán
Jorge L
JL
García-Sastre
Adolfo
A
Bernard
Kristen A
KA
Shi
Pei-Yong
PY
D000222:Adaptation, Physiological; D000818:Animals; D002460:Cell Line; D005260:Female; D016899:Interferon-beta / Q000494:pharmacology; D051379:Mice; D008809:Mice, Inbred C3H; D009154:Mutation; D012367:RNA, Viral / Q000096:biosynthesis*; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D014779:Virus Replication / Q000187:drug effects; D014901:West Nile Fever / Q000517:prevention & control / Q000821:virology*; D014902:West Nile virus / Q000502:physiology*
C080107:NS4B protein, flavivirus; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; D016899:Interferon-beta