Analysis of Amino Acid Changes in Fusion protein of Virulent Newcastle Disease Virus from vaccinated poultry in Nigerian Isolates

Abstract

The roles of Fusion gene in the virulence of Newcastle disease virus has been well established but the extent of its variation among the newly identified XIV, XVII and XVIII genotypes which are predominantly found in Central and West Africa have until recently been understudied and LaSota vaccine strain protection against mortality and morbidity against XIV genotype is the least reported. In this study, F gene of vNDV isolated from samples collected in Nigeria from chicken cadaver from vaccinated chicken flocks showing high mortality, clinical signs and post-mortem lesions attributable to ND during March and April, 2020 were sequenced and analysed for information about genetic changes. Results showed that all isolates from our study have virulent cleavage site sequence 112-RRRKR-116/F117 and clustered within genotype XIVb. Sequence analysis show K78R mutation in the A2 antigenic epitope in all isolates, and more along the F gene which vary in some instances within the isolates. Mutation in this A2 antigenic epitope has been reported to induce escape mutation to monoclonal antibodies generated using NDV LaSota strain. Averages of antigenic variability and percentage homology between the isolates and commonly used vaccines is 0.24; 81.40% and 0.22; 81.90% for LaSota and Komorov vaccines respectively. Nucleotide sequences was assigned accession numbers OK491971-OK491977. Many substitutions were observed in the isolates and some of their functions are yet to be determined.

Possible Outbreak of Newcastle Virus Infection in the Face of Increasing Trend of Backyard Poultry Farm Management Interface in Nigeria: A Public Health and Food Security Threat

“…Seroprevalence investigations on birds carried out in several areas in Nigeria throughout the years revealed varied ranges from 38% to 74.3% [133]. In more recent seroprevalence studies (table 1), the figures have not considerably changed as the prevalence range from as low as 3.2% Sanni OOF, et al [134] to as high as 67.9% Snoeck CJ, et al [135], which goes to show that without a doubt, Newcastle disease (ND) is enzootic in Nigeria. Recently, attempts were made by using molecular techniques at defining the genotypes and molecular epidemiology of the circulating virus in West and Central Africa including Nigeria [93,[136][137][138].…”

“…FAO revealed that one of the major constraints to the achievement of an effective poultry disease control strategy is the ignorance of poultry keepers on appropriate procedures such as vaccination, pen spacing, breeding, and withdrawal of sick birds. According to Okwor et al [134], farmers in Nigeria have paucity of information about disease prevention. Adam VY, et al [207] found that inadequate knowledge regarding the Newcastle disease virus, negative perceptions of ND, lack of basic training on animal health, preventive and control mechanisms all play a role in poor poultry management and increased disease outbreaks.…”