Peste des petits ruminants virus (PPRV), which is the only member of the Morbillivirus caprinae species and belongs to the genus Morbillivirus within the Paramyxoviridae family, causes the highly contagious viral sickness “Peste des petits ruminants (PPR).” PPR is of serious economic significance for small ruminant production, particularly in Africa. Control of this critical disease depends highly on successful vaccination against the PPRV. An in-depth understanding of the genetic evolution of the live-attenuated PPR vaccine Nigeria 75/1 strain used in Africa is essential for the successful eradication of this disease by 2030. Therefore, this study investigated the possible genetic evolution of the PPR vaccine produced by various African laboratories compared with the master seed available at AU-PANVAC. RT-PCR was performed to amplify a segment of the hypervariable C-terminal part of the nucleoprotein (N) from commercial batches of PPR vaccine Nigeria 75/1 strain. The sequences were analyzed, and 100% nucleotide sequence identity was observed between the master seed and vaccines produced. The results of this study indicate the genetic stability of the PPR vaccine from the Nigeria 75/1 strain over decades and that the vaccine production process used by different manufacturers did not contribute to the emergence of mutations in the vaccine strain.

Enzyme linked immunosorbent assays (ELISAs) have been developed for the detection of antibodies against contagious caprine pleuropneumonia (CCPP), the causative agent of which is Mycoplasma capricolum subsp. Capripneumoniae (Mccp). The currently available commercial CCPP competitive ELISA (CCPP cELISA) kit produced and supplied by IDEXX Company (Westbrook, Maine, United States) is relatively expensive for most African laboratories. To address this issue and provide a variety of choices, a sensitive and specific blocking-ELISA (b-ELISA) test to detect antibodies against CCPP was developed. We describe the newly developed CCPP blocking-ELISA based on the blocking of an epitope of a monoclonal antibody (Mccp-25) by a positive serum sample against the Mccp protein coated on a plate. The Percentage Inhibition (PI) cut-off value for the CCPP b-ELISA was set at 50 using 466 CCPP negative and 84 CCPP positive small ruminant sera. Of the negative sera, 307 were obtained from the Botswana National Veterinary Laboratory (BNVL) and 159 from the Friedrich-Loeffler-Institute (FLI) Germany. The 84 positive sera samples came from experimentally vaccinated goats at the AU-PANVAC facility in Debre-Zeit, Ethiopia. The relative diagnostic sensitivity and specificity of the CCPP b-ELISA was 93% and 88%, respectively. This test result indicated good correlation with that of the commercial CCPP cELISA by IDEXX Company (Westbrook, Maine, United States) with a Cohen’s κ agreement of κ agreement of 0.85. The newly developed CCPP b-ELISA will be useful in the detection of antibodies for the diagnosis CCPP and for sero-surveillance during vaccination campaigns.

An effective contagious caprine pleuropneumonia (CCPP) vaccine is essential for the increased production of healthy goats in a cost-effective manner and the prevention of animal-to-animal transmission for both domestic animals and wildlife. Quality control of this vaccine ensures that a reliable supply of pure, safe, and potent batches is obtained. As part of this control, in vitro quantification of Mycoplasma capricolum subsp. capripneumoniae (Mccp) protein in the final vaccines is required before the CCPP vaccine undergoes batch release and certification. The current method used for quantification is based on the measurement of total protein using the bicinchonic acid (BCA) test. This method quantifies the total amount of protein in the vaccine including contaminant protein from media, which can lead to overestimation of the quantity of Mccp protein, resulting in reduced vaccine immunogenicity. An immuno-capture ELISA (ICE) was developed for specific detection and quantification of the Mccp antigen in the CCPP vaccine. As the ICE detects and measures the amount of antigen between two layers of antibodies, capture and detecting antibodies are required. Mouse monoclonal antibodies (mAbs) that detect the Mccp antigen were produced and characterized. One of these mAbs, Mccp-25, was used to develop the ICE as an unlabelled capture antibody and horseradish peroxidase conjugated detecting antibody. The ICE was standardized and evaluated using an internal reference sample, experimental CCPP vaccines and commercial CCPP vaccines. A comparison between the polymerase chain reaction (PCR) and ICE showed good correlation between the two assays. Also, an in vitro ICE method correlated well with an in vivo sero-conversion in goats that were vaccinated with selected test vaccines. The sensitivity of the ICE was estimated at 30ngml.

[This corrects the article DOI: 10.1155/2020/4236807.].

The Peste des Petits Ruminants (PPR) live attenuated vaccines, the PPR virus (PPRV) Nigeria 75/1 strain (lineage II) and PPRV India Sungry 96 strain (lineage IV), currently used for control and eradication programme are very efficient vaccines as they provide the host, sheep and goats, a lifelong immunity after a single minimum recommended dose of 10^2.5 TCID₅₀/mL. Unfortunately, both live attenuated vaccines are thermolabile and their use requires maintaining the cold chain from the manufactory premises to the field as most PPR-infected regions are facing of hot climate, with poor infrastructure, and the maintenance of an effective cold chain remains a challenge. To address this challenge, efforts have focused on developing thermotolerant (ThT) PPR vaccines using different stabilisers and improving the freeze-drying process. This study aimed to define the criteria for the evaluation of the stability of ThT PPR vaccines. A total of 37 batches of freeze-dried PPR vaccines using the PPRV Nigeria 75/1 strain, including eight (8) and twenty-nine (29) vaccines labelled as ThT and conventional formulations, respectively, were tested to evaluate the stability at temperatures of 40 °C to simulate the field conditions in some hot climate regions. All the vaccine batches included in this study initially showed acceptable levels of residual moisture, below 3%, and titres above the minimum WOAH standard requirement of 10^2.5 TCID₅₀/mL. Following the incubation at 40 °C, 56.7% and 46% of the 37 vaccine batches tested retained titres above 10^2.5 TCID₅₀/mL on day 3 and day 5, respectively. These vaccines use stabilisers such as skimmed milk, lactalbumin–sucrose, trehalose and one unnamed product (which may be protected for patent). The mean of titre loss among the PPR vaccines maintaining titres above 10^2.5 TCID₅₀/mL was 0.78 log10 at day 3 and 0.99 log10 at day 5, suggesting a significant early degradation during the first 3 days. Based on these data, it is proposed that thermotolerant PPR vaccines should maintain a minimum titre of 10^2.5 TCID₅₀/mL for vaccine dose on day 5 post-incubation at 40 °C with a titre loss below 1 log10 per mL. Preliminary immunogenicity test results showed that the PPR ThT vaccine meeting this criterion could be used in the field without maintaining a cold chain for up to 3 weeks, offering a practical solution for vaccination in remote areas.

Peste des Petits Ruminants (PPR) disease is widely distributed in Africa. Live attenuated PPR vaccines are produced using approved Nigeria 75/1 and Sungri/96 strains by the World Organisation of Animal Health (WOAH) to control the disease. These PPR vaccines are very efficacious; however, the main challenge is the maintaining of the cold chain during vaccine distribution and delivery. This study evaluated the thermotolerance of freeze-dried and reconstituted PPR Nigeria 75/1 vaccines from vaccine manufacturers using eight stabilizer formulations (lactalbumin hydrolysate and sucrose, sucrose and peptone, Weybridge medium, trehalose, Lactose and N-Z Amine, lactalbumin hydrolysate, sucrose and L glutamine, skimmed milk, and lactalbumin hydrolysate, maltose and gelatine). Aliquots of the reconstituted PPR vaccine batches were titrated after 2, 4, and 6 h of storage at 4 °C and 40 °C. The PPR vaccines were also titrated after storage at 40 °C and 45 °C for 3 and 5 days. The results showed that reconstituted PPR vaccine stabilized with lactalbumin hydrolysate–sucrose promoted tolerance at 40 °C for 6 h. It was also noted that all reconstituted PPR vaccine formulations except the formulation stabilized with lactalbumin hydrolysate–maltose–gelatine maintained the titre above a 10^2.5 TCID₅₀/dose after 4 h of storage at 4 °C. Furthermore, the results showed that the PPR vaccine formulation containing lactalbumin hydrolysate sucrose was as the only one that maintained the titres above 10^2.5 TCID₅₀/dose after storage at 45 °C for 5 days, with a titre loss of 10^0.95 TCID₅₀/dose. Therefore, vaccine manufacturers producing PPR vaccines for use in tropical field regions could preferably use lactalbumin hydrolysate–sucrose stabilizer in vaccine formulation.