Genetic diversity of Newcastle disease virus in Pakistan: a countrywide perspective

Abstract

BackgroundNewcastle disease (ND) is one of the most deadly diseases of poultry around the globe. The disease is endemic in Pakistan and recurrent outbreaks are being reported regularly in wild captive, rural and commercial poultry flocks. Though, efforts have been made to characterize the causative agent in some of parts of the country, the genetic nature of strains circulating throughout Pakistan is currently lacking.Material and methodsTo ascertain the genetics of NDV, 452 blood samples were collected from 113 flocks, originating from all the provinces of Pakistan, showing high mortality (30–80%). The samples represented domesticated poultry (broiler, layer and rural) as well as wild captive birds (pigeons, turkeys, pheasants and peacock). Samples were screened with real-time PCR for both matrix and fusion genes (1792 bp), positive samples were subjected to amplification of full fusion gene and subsequent sequencing and phylogenetic analysis.ResultsThe deduced amino acid sequence of the fusion protein cleavage site indicated the presence of motif (112RK/RQRR↓F117) typical for velogenic strains of NDV. Phylogenetic analysis of hypervariable region of the fusion gene indicated that all the isolates belong to lineage 5 of NDV except isolates collected from Khyber Pakhtunkhwa (KPK) province. A higher resolution of the phylogenetic analysis of lineage 5 showed the distribution of Pakistani NDV strains to 5b. However, the isolates from KPK belonged to lineage 4c; the first report of such lineage from this province.ConclusionsTaken together, data indicated the prevalence of multiple lineages of NDV in different poultry population including wild captive birds. Such understanding is crucial to underpin the nature of circulating strains of NDV, their potential for interspecies transmission and disease diagnosis and control strategies.

Pathotypic characterization of the Newcastle disease virus isolated from commercial poultry in northwest Iran

“…Studies on NDV pathotyping in countries bordering Iran have also revealed the presence of virulent strains. In Turkey, virulent NDVs were isolated among the wild bird population in the Lake Van basin by analyzing for virulent F protein using real time RT-PCR (rRT-PCR) (25) (27,28). Our results are in agreement with previous studies reporting the detection of virulent NDVs in Iran (10,12).…”

Molecular epidemiology of respiratory viruses in commercial chicken flocks in Pakistan from 2014 through to 2016

“…Furthermore, the inability of live vaccines to elicit a protective immune response might be due to an inadequate cold chain supply system, inappropriate route of vaccination, or incorrect vaccination schedules. It has been reported that the currently applied AAVV-1 vaccines give better protection against the velogenic AAVV-1 s isolated from the 1930s through to the 1970s (Herts33/56, California 71) than those more recently isolated [38]. Hence parameters for selection of vaccine strains need to be reconsidered.…”

“…Co-infections were common for AIV and AAVV-1 (9 AIV/ AAVV-1 coinfected flocks) but less common for the other avian viruses of interest (Table 1). Briefly, 9 flocks (6,21,23,38,41,42,66,67,68) were found positive for AIV (H9) and AAVV-1 coinfections. AAVV-1 + aMPV, AIV + aMPV and AAVV-1 + IBV coinfections were detected only in flock number 69, 70 and 80, respectively.…”

Comparative Study of Different Vaccination Routes Against Newcastle Disease in Layer Chickens

“…Immune responses to ND vaccines are influenced by routes (ocular, injection, drinking water, aerosol or nasal) of vaccination. Eye drop vaccination stimulates Harderian gland to produce local antibodies (Shabbir et al 2013). Vaccines given through mucosal surfaces (eye drop and nasal) generate mucosal immune response.…”