Sequence analysis of temperature sensitive and ?neuraminidase-tolerant? mutants of Newcastle disease virus (strain Beaudette C)

Abstract

Summary. Nucleotide sequence analysis of temperature sensitive and "neuraminidase-tolerant" mutants of Newcastle disease virus has identified sites in the haemagglutinin-neuraminidase protein which may be important in folding and function.Newcastle disease virus, family Paramyxoviridae, genus Paramyxovirus, contains two surface glycoproteins, haemagglutinin-neuraminidase (HN), which binds to and cleaves neuraminic acid from host receptors, and fusion protein (F), which is responsible for fusing host and virus membranes. Both glycoproteins are embedded in a lipid bilayer. Closely apposed to this lipid bilayer is the matrix protein (M) which may interact with the cytoplasmic region(s) of the membrane glycoproteins.The temperature sensitive mutant ts53, originally isolated by Dahlberg [5] following nitrous acid mutagenesis of the thermostable strain ofNDV Beaudette C, was earlier shown to possess a thermolabile HN glycoprotein (determined by assaying both haemagglutination and neuraminidase activities), and to produce a matrix protein which was susceptible to proteolytic cleavage in vivo at the non-permissive temperature (42 °C) in CEF [7].To locate the genetic lesion(s) in this non-revertible ts mutant we sequenced the M and HN genes from wild type (wt) and ts53 virions using M and HN gene specific oligonucleotide primers, virion RNA and reverse transcriptase, as described earlier [-21]. In addition, we have isolated "neuraminidase-tolerant" mutants of the Beaudette C strain and sequenced the HN genes of these mutants