Pathotyping and Phylogenetic Characterization of Newcastle Disease Viruses Isolated in Peru: Defining Two Novel Subgenotypes Within Genotype XII

Abstract

Infections of poultry with virulent strains of avian paramyxovirus 1 (APMV-1), also known as Newcastle disease viruses (NDVs), cause Newcastle disease (ND). This highly contagious disease affects poultry and many other species of birds worldwide. In countries where the disease is prevalent, constant monitoring and characterization of isolates causing outbreaks are necessary. In this study, we report the results of pathogenicity testing and phylogenetic analyses of seven NDVs isolated from several regions of Peru between 2004 and 2015. Six viruses had intracerebral pathogenicity indices (ICPIs) of between 1.75 and 1.88, corresponding to a velogenic pathotype. The remaining virus had an ICPI of 0.00, corresponding to a lentogenic pathotype. These results were consistent with amino acid sequences at the fusion protein (F) cleavage site. All velogenic isolates had the polybasic amino acid sequence RRQKR↓F at the F cleavage site. Phylogenetic analyses of complete F gene sequences showed that all isolates are classified in class II of APMV-1. The velogenic viruses are classified in genotype XII, while the lentogenic virus is classified in genotype II, closely related to the LaSota vaccine strain. Moreover, tree topology, bootstrap values, and genetic distances observed within genotype XII resulted in the identification of novel subgenotypes XIIa (in South America) and XIIb (in China) and possibly two clades within genotype XIIa. All velogenic Peruvian viruses belonged to subgenotype XIIa. Overall, our results confirm the presence of genotype XII in Peru and suggest that it is the prevalent genotype currently circulating in our country. The phylogenetic characterization of these isolates helps to characterize the evolution of NDV and may help with the development of vaccines specific to our regional necessities.

Phylogeny, pathogenicity and transmissibility of a genotype XII Newcastle disease virus in chicken and goose

“…These indicated that the E115 strain was a virulent NDV strain, according to the OIE standard criteria. A phylogenetic tree based on the complete F gene sequence (1–1662 nt) showed that the E115 strain was assigned to subgenotype XIIb described by Chumbe et al () and was distinct from clusters of XIIa from Peru and XIId from Vietnam (Figures and ). The TMRCA for genotype XII NDVs in China was 2008.5 (95% highest posterior density [HPD] lower: 2000.9; 95% HPD higher: 2018.3).…”

“…Genotype XII NDVs were first reported in Peru, South America, and they have contributed to several ND outbreaks in chickens since 2004 (Chumbe et al, ; Diel, Susta, et al, ). Based on the ICPI and the sequence of the cleavage site in the F protein, these isolates were identified as virulent NDV strains.…”

“…The presence of genotype XII NDVs in China was confirmed in geese from Guangdong province in 2010–2011. However, phylogenetic analysis showed that the isolates from South America belonged to subgenotype XIIa, while those from China belonged to subgenotype XIIb (Chumbe et al, ). Confusingly, these strains have only been isolated from geese in Guangdong province, and no outbreaks have been reported to be associated with these strains.…”

Genotype-matched Newcastle disease virus vaccine confers improved protection against genotype XII challenge: The importance of cytoplasmic tails in viral replication and vaccine design

“…Subgenotype XIIa strains have been isolated only in South America (Peru and Colombia) [13–15], XIIb strains have been isolated only in the province of Guangdong in China [10,16] and XIId strains were recently reported in Vietnam [12]. XIIc is a potential subgenotype composed of strains isolated between 1986 and 2005, nevertheless only partial sequences of the F gene are available for these strains, therefore it cannot be consider as a proper subgenotype yet [13]. In Peru, XIIa is the only genotype isolated so far [13] and despite intensive vaccination campaigns, several outbreaks are reported every year [17], even in vaccinated flocks.…”

“…XIIc is a potential subgenotype composed of strains isolated between 1986 and 2005, nevertheless only partial sequences of the F gene are available for these strains, therefore it cannot be consider as a proper subgenotype yet [13]. In Peru, XIIa is the only genotype isolated so far [13] and despite intensive vaccination campaigns, several outbreaks are reported every year [17], even in vaccinated flocks. This can be explained by antigenic differences between vaccine and genotype XII circulating strains.…”