Use of an enzyme-linked immunosorbent assay for the detection of IgG antibodies to rinderpest virus in epidemiological surveys

Interference in the vaccination of cattle against rinderpest virus by antibodies against peste des petits ruminants (PPR) virus

The ability of the attenuated vaccine 75/1 of peste des petits ruminants to interfere with rinderpest vaccination in cattle was investigated experimentally. Young cattle (93) were selected and tested as being negative for antibodies against RP or PPR viruses. These were vaccinated with the peste des petits ruminants attenuated vaccine strain PPR75/1. All animals produced specific antibodies against the peste des petits ruminants vaccine after one or two doses. The cattle were then vaccinated with attenuated rinderpest vaccine. Two months later, 88 of these animals were sampled and 21/88 were positive for antibodies specific for rinderpest. The 67 negative animals received a second rinderpest vaccine dose after which 31seroconverted. The 36 animals which failed to seroconvert were re-vaccinated, of these 28 seroconverted. This study highlights the interference by peste des petits ruminants vaccination, presumably through production of antibodies that cross react with the live rinderpest virus in the vaccine used. This interference is also observed after vaccination against rinderpest followed by subsequent administration of peste des petits ruminants vaccine.

Monoclonal antibody-based competitive ELISA for simultaneous detection of rinderpest virus and peste des petits ruminants virus antibodies

An experimental competitive enzyme-linked immunosorbent assay (morbillivirus cELISA) using a recombinant N antigen (rRPV N) expressed in a baculovirus and a ruminant morbillivirus (RPV and PPRV)-specific monoclonal antibody (P-13A9) was developed for simultaneous detection of rinderpest virus (RPV) and peste des petits ruminants virus (PPRV) antibodies and its diagnostic performance was evaluated. A set of known reference antisera against RPV and PPRV belonging to different lineages, experimental sera from cattle vaccinated for a RPV of Asian lineage, and field sera from cattle and sheep/goat populations known to be positive (West Africa) and negative (Korea) for RPV and PPRV were used for the evaluation. Morbillivirus cELISA results on the panel of experimental RPV and PPRV antisera showed high correlation (r=0.97) between the whole virus and the rRPV N antigens, suggesting that the rRPV N contains a ruminant morbillivirus-specific antigenic determinant recognized by the P-13A9 and it may be suitable as an ELISA antigen in place of the whole virus. Morbillivirus cELISA detected anti-RPV and anti-PPRV antibodies in all reference RPV and PPRV antisera containing VN titers >/=1:8, suggesting that the assay can simultaneously detect antibodies against RPV and PPRV. Anti-RPV antibody was detected by morbillivirus cELISA in vaccinated cattle as early as the VNT and continued to be detectable by both the cELISA and the VNT until termination of the study. When applied to field samples from Africa, morbillivirus cELISA showed good agreement with a RP cELISA kit (kappa value of 0.86) in bovine sera and with a peste des petits ruminant cELISA kit (kappa value of 0.81) in caprine/ovine sera. Usefulness of morbillivirus cELISA using the rRPV N protein was discussed.

Observations on the pathogenicity for sheep and goats and the transmissibility of the strain of virus isolated during the rinderpest outbreak in Sri Lanka in 1987

The pathogenicity for sheep and goats of the virus strain that caused acute rinderpest in cattle and domestic buffalo in Sri Lanka after an interval of over 40 years has been examined. The results show that it can cause overt clinical disease in goats, but only mild or unapparent infection in sheep. The disease was transmitted from infected sheep to in-contact susceptible sheep and calves.

Simple and rapid dot-enzyme immunoassay for visual detection of rinderpest antibodies in bovine and caprine sera

A modified solid phase enzyme immunoassay (EIA) is described for visual detection of anti-rinderpest virus (RPV) antibodies in cattle and goat sera. Dots of RPV antigens were adsorbed to nitrocellulose (NC) paper (hence Dot-EIA) and the adsorptive reactive sites were blocked with skim milk powder. After immersion in bovine or caprine test serum bound antibodies were reacted with a peroxidase-conjugated anti-bovine or anti-caprine IgG (H & L), respectively. Positive reactions were easily visualized as red-brown dots after enzyme degradation of a substrate containing hydrogen peroxide and amino-ethylcarbazole (AEC). The Dot-EIA was comparable to the serum neutralisation (SN) test in its ability to detect antibody in bovine sera seven or ten days after experimental infection (DPI) with live attenuated Kabete "O" (RBOK) strain of RPV (grown in Vero cells) by a combination of subcutaneous (s/c), intravenous (i/v) or intranasal (i/n) routes. Early (seven DPI) RPV antibodies were detected in a serum sample from one goat experimentally infected with RPV by combined s/c-i/v routes but not in another goat only infected intranasally. The specificity of the Dot-EIA was equal to that of the SN test, as serum samples, collected from these experimental animals and those inoculated with non infected Vero cell culture fluid, with SN titres of 0.3 or lower were all negative by Dot-EIA. The Dot-EIA may have potential application as a rapid, simple and economical field test in diagnosis of rinderpest, vaccination surveillance and other seroepidemiological studies.