Monkey CV1 cell line expressing the sheep-goat SLAM protein: a highly sensitive cell line for the isolation of peste des petits ruminants virus from pathological specimens

Abstract

Peste des petits ruminants (PPR) is an important economically transboundary disease of sheep and goats caused by a virus which belongs to the genus Morbillivirus. This genus, in the family Paramyxoviridae, also includes the measles virus (MV), canine distemper virus (CDV), rinderpest virus (RPV), and marine mammal viruses. One of the main features of these viruses is the severe transient lymphopaenia and immunosuppression they induce in their respective hosts, thereby favouring secondary bacterial and parasitic infections. This lymphopaenia is probably accounted for by the fact that lymphoid cells are the main targets of the morbilliviruses. In early 2000, it was demonstrated that a transmembrane glycoprotein of the immunoglobulin superfamily which is present on the surface of lymphoid cells, the signalling lymphocyte activation molecule (SLAM), is used as cellular receptor by MV, CDV and RPV. Wild-type strains of these viruses can be isolated and propagated efficiently in non-lymphoid cells expressing this protein. The present study has demonstrated that monkey CV1 cells expressing goat SLAM are also highly efficient for isolating PPRV from pathological samples. This finding suggests that SLAM, as is in the case for MV, CDV and RPV, is also a receptor for PPRV.

Fig. 1

Photographs of the RT-PCR results to identify the cell clones potentially expressing the goat SLAM: (A) amplicons corresponding to the RT-PCR of the β-actin mRNA; (B) amplicons corresponding to the RT-PCR of the goat SLAM mRNA. Lane M, 100 bp DNA molecular weight ladder; lane C−, control cells non-transfected with the SLAM plasmid; lane 1A, transfected selected clone 1; lane 2B, transfected selected clone 2; lane 3C, transfected selected clone 3; lane 4D, transfected selected clone 4; lane 5E, transfected selected clone 5.

Fig. 2

Photographs of the microscopic observation of the CHS-20 cells: (A) non infected cells, (B) cells infected with the attenuated PPRV Nigeria 75/1 (1 day post infection), (C) cells infected with the pathological specimen NIG/08-43 (2 days post infection), and (D) cells infected with the pathological sample CIV/09-01P (2 days post infection). Some of the syncytia are shown by the arrows.

Fig. 3

Monitoring the efficiency of CHS-20, CV1 and Vero cell lines in isolating PPRV from pathological specimens (lung, lymph node, spleen and liver) collected from the same animal: gel electrophoresis photograph of DNA amplified by RT-PCR of RNA extracted from different samples: 1 =  supernatant at day 2 post infection; 2 = supernatant at day 4 post infection; 3 = supernatant at day 8 post infection; 4 = cells collected after trypsination at day 8 post infection; − = negative control; + = positive control; −C1 = non-infected CHS20 cells; −C2 = non-infected CV1 cells; −C3 = non-infected Vero cells.