Peste des petits ruminants virus in Tibet, China

Abstract

Serologic and molecular evidence indicates that peste des petits ruminants virus (PPRV) infection has emerged in goats and sheep in the Ngari region of southwestern Tibet, People's Republic of China. Phylogenetic analysis confirms that the PPRV strain from Tibet is classified as lineage 4 and is closely related to viruses currently circulating in neighboring countries of southern Asia.

Figure 1

A) Distribution of outbreaks of peste des petits ruminants disease in Tibet, China, 2007. Triangles indicate outbreaks confirmed by ELISA. Circles indicate outbreaks confirmed by reverse transcription–PCR (RT-PCR) and quantitative RT-PCR. Squares indicate outbreaks confirmed by ELISA and molecular methods. B) Cycle threshold (Ct) values (determined by use of q-RT-PCRs on samples) by county.

Figure 2

Phylogenetic relationship between peste des petits ruminants virus (PPRV) detected in Tibet, China, in 2007 and other virus isolates. PPRV strains sequenced in this study are highlighted in gray. Other sequences are from GenBank. Phylogenetic analyses were completed with MEGA 3.1 software that used a neighbor-joining algorithm and absolute distances and that followed 1,000 bootstrap replicates. The RBOK vaccine strain of rinderpest virus was included as an outgroup. The tree is based on the partial sequence of the fusion (F) protein gene (A) and the nucleocapsid (N) protein gene (B). Different classifications were used for the phylogenetic comparisons for the West African lineages 1 and 2. Nigeria and related strains have been classified as lineage 1; the Côte d’Ivoire and related strains have been classified as lineage 2 (1). Later research reversed this order in classifying the lineages in N gene analyses (2).