Conclusion
In summary, multiple subtypes of PRRSV commonly coexist on single pig
farms. NADC34-like PRRSV, which correlated with the death curve, was
first reported to be one of the main endemic strains on a pig farm in
Heilongjiang Province, China. NADC34-like PRRSV from this farm had high
nucleotide similarity and a 100-aa deletion in the NSP2 protein but no
recombination. The genetic diversity of NADC34-like PRRSV is relatively
singular, but it has a relatively high evolution rate. The prevalence of
NADC34-like PRRSV on other pig farms in China needs further attention.