Recent advances in the laboratory diagnosis of peste des petits ruminants

Abstract

Peste des petits ruminants (PPR) is a highly contagious and economically important, viral disease of small ruminants caused by the peste des petits ruminants virus (PPRV), which belongs to the genus Morbilivirus in the family Paramyxoviridae. PPR control is achieved mostly through vaccination and/or slaughter of susceptible animals coupled with clinical or laboratory-based diagnosis. Since clinical signs of PPR are not disease-specific and clinical diagnostics is not reliable, it should be confirmed by laboratory testing. Laboratory confirmation of clinical suspicions is made by detection of PPRV in blood, swabs or post-mortem tissues through classical virus isolation (VI), agar gel immunodiffusion (AGID)/agar gel precipitation test (AGPT), counter-immunoelectrophoresis (CIE), immunoperoxidase test (IPT) or enzyme-linked immunosorbent (ELISA) assays. However, these conventional methods have been superseded by more rapid, sensitive and accurate molecular diagnostic techniques based on the amplification of parts of either nucleocapsid (N) or fusion (F) protein gene, such as RT-PCR, real-time RT-PCR, reverse transcription loop-mediated isothermal amplification (RT-LAMP), reverse transcription recombinase polymerase amplification (RT-RPA) and Oxford nanopore MinION technology. Although these molecular diagnostic assays are accurate, rapid and sensitive, they have to be performed in laboratory settings, and samples must be transported under appropriate conditions from the field to the laboratory, which can delay the confirmation of PPRV infection. The recently developed immunochromatographic lateral flow device (IC-LFD) assay can be used in the field (“pen-side”) without the need for expensive equipment, so a well-established laboratory is not required. The control and eventual eradication of PPR is now one of the top priorities for the Food and Agriculture Organization (FAO) and the World Organization for Animal Health (OIE). In 2015, the international community agreed on a global strategy for PPR eradication, setting 2030 as a target date for elimination of the disease