Detection and genetic characterization of peste des petits ruminants virus in free-living bharals (Pseudois nayaur) in Tibet, China.

Peste des petits ruminants (PPR) is an important viral disease of sheep and goats. The wildlife hosts of PPR, which may play an important role in the epidemiology of this disease, are not well characterized. The research was undertaken to study the infection of PPR virus (PPRV) in free-living bharals (Pseudois nayaur) in Tibet, China. In 2007, PPRV infection was confirmed in two bharals in Rutog County of Tibet based on clinical signs and detection of PPRV RNA in tissue samples. In 2008, PPRV infection was found in one bharal in Ge'gyai County of Tibet by competitive ELISA, reverse transcription-polymerase chain reaction, and sequence analysis of PPRV fusion protein (F) and nucleoprotein (N) gene segments. The PPRV variant identified in infected bharal was closely related to other circulating PPRV variants recently identified in sheep and goats from Tibet. This is the first report of PPRV infection in free-living bharals.

Peste des petits ruminants virus in Tibet, China.

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.

Development of one-step real-time RT-PCR assay for detection and quantitation of peste des petits ruminants virus.

In this study, a rapid and specific TaqMan-based, one-step real-time quantitative reverse transcription PCR (qRT-PCR) has been described for the detection of peste des petits ruminants virus (PPRV). Primers and probe were designed based on the nucleocapsid protein gene sequence. The real-time qRT-PCR assay was able to detect PPRV isolates from very distinct geographical areas (Africa, Middle East and Asia). The specificity of the assay was assessed by including rinderpest virus and other morbillivirus RNAs but none of these tested positive in the assay. The analytical sensitivity of the real-time qRT-PCR assay was achieved through the construction of an in-house PPRV cRNA for the generation of a standard curve. The detection limit of the assay was found to be 8.1 RNA copies per reaction mixture. The assay had excellent intra- and inter-assay reproducibility. In total 30 field samples were screened for the presence of PPRV by conventional RT-PCR in parallel with qRT-PCR. The detection rate increased from 46.7% to 73.3% by use of the real-time qRT-PCR. The real-time qRT-PCR assay described in this report allows the rapid, specific and sensitive laboratory detection of PPRV in tissue samples from field cases.

[Sequence analysis of the nucleocapsid gene and genome promoter region of peste des petits ruminants virus of Chinese origin].

The N gene and genome promoter nucleotide sequence of a Chinese Peste des petits rumiants virus (PPRV) ("China/Tib/Gej/07-30") was firstly determined. The length of N gene was 1689 nucleotides with a single open reading frame (ORF). The nucleotide and deduced amino acid sequence was compared with the homologous region of other PPRV isolates. The nucleotide sequence of the "China/Tib/Gej/07-30" was 91.7%-97.6% identical to other PPRV isolates, while a homology of 94.9%-98.5% could be observed at the amino acids level. The N gene encoded a protein of 525 amino acids. Several sequence motifs were identified on the basis of conservation in the PPRVs and the morbilliviruses. The genome length of promoter region was 107 nucleotides with 91.8%-98.2% identity to other PPRV isolates. Phylogenetic analysis showed that the "China/Tib/Gej/07-30" belonged to the Asian lineage.