A molecular, epidemiological and pathogenicity analysis of pigeon paramyxovirus type 1 viruses isolated from live bird markets in China in 2014-2021

To expand our understanding of the epidemiology of pigeon paramyxovirus type 1 (PPMV-1) in China, risk-based active surveillance was undertaken with pigeon swabs collected from live bird markets in 2014-2021. Seventy-six PPMV-1 strains were isolated from 12 provinces (60%) of the 20 provinces surveyed, and the positive rates of PPMV-1 varied from 0.50% to 3.19% annually. The complete genomic sequences of 18 representative viruses were analyzed, revealing a genome of 15,192 nucleotides, with the gene order 3'-NP-P-M-F-HN-L-5'. All isolates contained the ¹¹²RRQKRF¹¹⁷ cleavage site in the fusion (F) protein, a characteristic generally associated with virulent Newcastle disease viruses (NDVs), and the intracerebral pathogenicity index values (1.05-1.41) of four isolates indicated their virulence. A challenge experiment also demonstrated that all four isolates are pathogenic to pigeons, with morbidity rates of 60-100% and mortality rates of 0-30%. A further analysis of the functional domains of the F and HN proteins revealed several mutations in the fusion peptide, signal peptide, neutralizing epitopes, heptad repeat region, and transmembrane domains, and the substitution of cysteine residue 25 (C25Y) and substitutions in the HRb region (V287I) of the F protein and the transmembrane domain (V45A) of the HN protein may play important roles in PPMV-1 virulence. In a phylogenetic analysis based on the complete sequences of the F gene, all eighteen isolates all clustered into sub-genotype VI.2.1.1.2.2 (VIb) in class II, and shared high nucleotide sequence identity, indicating that the PPMV-1 strains in sub-genotype VI.2.1.1.2.2 are the predominant PPMV-1 viruses in pigeons in China and that the variations in these viruses have been relatively stable over the past 8 years. This study identifies the genetic and pathogenicity characteristics of the PPMV-1 strains prevalent in China and extends our understanding of the prevalence of this virus in China.

Genetic characterization and phylogeny of pigeon paramyxovirus isolate (PPMV-1) from Pakistan

Background

Knowing the genome characteristics of circulating Newcastle disease viruses [avian paramyxoviruses (APMV-1) and pigeon paramyxoviruses (PPMV-1)] is important to devise appropriate diagnostics and control strategies. APMVs originating from chicken and wildlife in Pakistan are well-elucidated; nevertheless, molecular characterization for the circulating PPMV-1 is largely unknown.

Findings

Here, we have performed fusion (F) and hemagglutinin (HN) gene based characterization of PPMV-1 isolated from an outbreak in a pigeon flock. With F₀ proteolytic cleavage site (₁₁₂RRQKR↓F₁₁₇), characteristic of velogenic/mesogenic serotype, the complete F and HN gene based sequence analysis of the isolate revealed evolutionary relationship to genotype VI. Further analysis of hyper-variable region of F-gene demonstrated clustering of the study isolate with genotype VIb. The deduced residue analysis for both F and HN protein showed a number of substitution mutations in the functional domains distinct from representative strains of each genotype including the vaccine strains; some of them were found exclusive to the study isolate.

Conclusions

Though limited and preliminary data, the findings enhance our knowledge towards circulating strains of PPMVs in Pakistan. Further studies are needed to ascertain its potential for transmission in the wild birds, commercial and backyard poultry and its subsequent shedding into the environment.