Genetic diversity and molecular characterization of avian paramyxoviruses from wild birds in South Korea between 2020 and 2024

Avian paramyxoviruses (APMVs) are economically important pathogens in the poultry industry, and wild waterfowl are considered reservoirs contributing to the spread of APMVs. In the present study, we investigated the prevalence and molecular characterization of APMVs in wild birds in South Korea between September 2020 and February 2024. A total of 27 APMVs were obtained, with a mean isolation rate of 0.35%. The APMV serotypes were identified as APMV-1 (n = 12), APMV-4 (n = 13), APMV-6 (n = 1), and APMV-13 (n = 1). Viral RNA genomes were amplified, and nearly complete genomic sequences were recovered using the single-primer amplification (SISPA) approach. All APMV isolates possessed a monobasic cleavage site in the fusion (F) protein, suggesting that they are low-pathogenic strains. Phylogenetic analysis based on complete F protein sequences revealed that APMV-1 isolates classified into class I sub-genotype 1.2 and class II sub-genotype I.2. Notably, APMV-1 isolates within class I sub-genotype 1.2 exhibited several amino acid substitutions compared to Newcastle disease virus (NDV) vaccine strains. To our knowledge, this study provides the first molecular evidence for the presence of a genotype II APMV-4 strain in wild birds from South Korea, suggesting the considerable genetic diversity of APMVs currently circulating among wild bird populations. Taken together, the nearly complete genomic sequences and genetic characterization of diverse APMV subtypes obtained in this study provide a valuable foundation for future research on their molecular evolution, antigenic variation, and epidemiological behavior.