RT Journal Article SR Electronic(1) A1 Samal, Sweety A1 Kumar, Sachin A1 Khattar, Sunil K. A1 Samal, Siba K.YR 2011 T1 A single amino acid change, Q114R, in the cleavage-site sequence of Newcastle disease virus fusion protein attenuates viral replication and pathogenicity JF Journal of General Virology, VO 92 IS 10 SP 2333 OP 2338 DO https://doi.org/10.1099/vir.0.033399-0 PB Microbiology Society, SN 1465-2099, AB A key determinant of Newcastle disease virus (NDV) virulence is the amino acid sequence at the fusion (F) protein cleavage site. The NDV F protein is synthesized as an inactive precursor, F0, and is activated by proteolytic cleavage between amino acids 116 and 117 to produce two disulfide-linked subunits, F1 and F2. The consensus sequence of the F protein cleavage site of virulent [112(R/K)-R-Q-(R/K)-R↓F-I118] and avirulent [112(G/E)-(K/R)-Q-(G/E)-R↓L-I118] strains contains a conserved glutamine residue at position 114. Recently, some NDV strains from Africa and Madagascar were isolated from healthy birds and have been reported to contain five basic residues (R-R-R-K-R↓F-I/V or R-R-R-R-R↓F-I/V) at the F protein cleavage site. In this study, we have evaluated the role of this conserved glutamine residue in the replication and pathogenicity of NDV by using the moderately pathogenic Beaudette C strain and by making Q114R, K115R and I118V mutants of the F protein in this strain. Our results showed that changing the glutamine to a basic arginine residue reduced viral replication and attenuated the pathogenicity of the virus in chickens. The pathogenicity was further reduced when the isoleucine at position 118 was substituted for valine., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.033399-0