Development and validation of an epitope-blocking ELISA using an anti-haemagglutinin monoclonal antibody for specific detection of antibodies in sheep and goat sera directed against peste des petits ruminants virus

Long-term trial of protection provided by adenovirus-vectored vaccine expressing the PPRV H protein

A recombinant, replication-defective, adenovirus-vectored vaccine expressing the H surface glycoprotein of peste des petits ruminants virus (PPRV) has previously been shown to protect goats from challenge with wild-type PPRV at up to 4 months post vaccination. Here, we present the results of a longer-term trial of the protection provided by such a vaccine, challenging animals at 6, 9, 12 and 15 months post vaccination. Vaccinated animals developed high levels of anti-PPRV H protein antibodies, which were virus-neutralising, and the level of these antibodies was maintained for the duration of the trial. The vaccinated animals were largely protected against overt clinical disease from the challenge virus. Although viral genome was intermittently detected in blood samples, nasal and/or ocular swabs of vaccinated goats post challenge, viral RNA levels were significantly lower compared to unvaccinated control animals and vaccinated goats did not appear to excrete live virus. This protection, like the antibody response, was maintained at the same level for at least 15 months after vaccination. In addition, we showed that animals that have been vaccinated with the adenovirus-based vaccine can be revaccinated with the same vaccine after 12 months and showed an increased anti-PPRV antibody response after this boost vaccination. Such vaccines, which provide a DIVA capability, would therefore be suitable for use when the current live attenuated PPRV vaccines are withdrawn at the end of the ongoing global PPR eradication campaign.

Prokaryotic expression of the V protein of the peste des petits ruminants virus and development of an indirect ELISA

In this study, we recombinantly expressed the V protein of the peste des petits ruminants virus (PPRV) and evaluated its diagnostic value for PPRV infection using an indirect ELISA (i-ELISA). The optimal concentration of the coated antigen of V protein was 15 ng/well at a serum dilution of 1:400, and the optimal positive threshold value was 0.233. A cross-reactivity assay showed that the V protein-based i-ELISA was specific to PPRV with consistent reproducibility and showed a specificity of 82.6% and a sensitivity of 100% with a virus neutralization test. Using the recombinant V protein as an antigen in ELISA is useful for seroepidemiological studies of PPRV infections.

The evaluation of five serological assays in determining seroconversion to peste des petits ruminants virus in typical and atypical hosts

Peste des petits ruminants (PPR) is an infectious viral disease, primarily of small ruminants such as sheep and goats, but is also known to infect a wide range of wild and domestic Artiodactyls including African buffalo, gazelle, saiga and camels. The livestock-wildlife interface, where free-ranging animals can interact with captive flocks, is the subject of scrutiny as its role in the maintenance and spread of PPR virus (PPRV) is poorly understood. As seroconversion to PPRV indicates previous infection and/or vaccination, the availability of validated serological tools for use in both typical (sheep and goat) and atypical species is essential to support future disease surveillance and control strategies. The virus neutralisation test (VNT) and enzyme-linked immunosorbent assay (ELISA) have been validated using sera from typical host species. Still, the performance of these assays in detecting antibodies from atypical species remains unclear. We examined a large panel of sera (n = 793) from a range of species from multiple countries (sourced 2015-2022) using three tests: VNT, ID VET N-ELISA and AU-PANVAC H-ELISA. A sub-panel (n = 30) was also distributed to two laboratories and tested using the luciferase immunoprecipitation system (LIPS) and a pseudotyped virus neutralisation assay (PVNA). We demonstrate a 75.0-88.0% agreement of positive results for detecting PPRV antibodies in sera from typical species between the VNT and commercial ELISAs, however this decreased to 44.4-62.3% in sera from atypical species, with an inter-species variation. The LIPS and PVNA strongly correlate with the VNT and ELISAs for typical species but vary when testing sera from atypical species.

Risk mapping using serologic surveillance for selected One Health and transboundary diseases in Cambodian goats

In Cambodia, goat production and meat consumption are customary among Muslim communities. Recently, goat meat has gained popularity among Cambodians. Goat farmers use a traditional management system, including grazing, requiring minimal labour. The close proximity between humans and animals could increase the risk of zoonotic disease transmission. A serological survey was undertaken to estimate the prevalence of some priority zoonoses and high-impact animal diseases in the Cambodian goat population. A total of 540 samples were collected from goats in six provinces and analysed with commercially available enzyme-linked immunosorbent assays for Brucella species, Q fever (Coxiella burnetii), Foot and Mouth Disease virus non-structural protein (FMDV NSP) and Peste des Petits Ruminants virus (PPRV). True seroprevalences with a 95% Confidence Interval (CI), taking into account imperfect tests, risk factors and odds ratios (ORs), were calculated to better understand the disease distribution and epidemiology. Independent variables used in statistical modellings included sex, body condition score, age, vaccination history, province and commune, while dependent variables were ELISA test results. The overall true prevalence of antibodies to Brucella spp., C. burnetii, FMDV and PPRV, were 0.1% (95% CI 0.0, 1.0), 7.2% (95% CI 5.3, 9.7), 57.7% (95% CI 53.1, 62.3) and 0.0% (95% CI 0.0, 0.0), respectively. There was no identified risk factor for brucellosis and PPR. The two risk factors for C. burnetii seropositivity were sex (p-value = 0.0005) and commune (p-value <0.0001). However, only the OR of C. burnetii seropositive female goat was significant at 9.7 (95% CI 2.7, 35.5) times higher than male. The risk factors of FMD NSP seropositivity were age (p-value = 0.001) and commune (p-value <0.0001). Only the age 'more than two-year-old' group with a significant OR of 6.2 (95% CI 2.1, 18.4) using the 'up to one-year-old' group as the reference. In summary, Brucella spp. seroprevalence was low, while no evidence of PPRV antibodies was detected in the goat populations. C. burnetii seroprevalence in female goats was significantly higher than for males, and there were significant differences in C. burnetii seroprevalence between communes. The overall FMDV NSP seroprevalence was high, especially in older animals. Vaccination should be advocated to protect animals from FMDV and improve productivity. As the impacts of these zoonoses on human and animal health were still unknown, further investigation of these zoonotic diseases' epidemiology is recommended.

Potential diagnostic application of the baculovirus-expressed recombinant truncated nucleocapsid protein of peste des petits ruminants in ELISA

The study describes the expression of recombinant truncated nucleocapsid protein (NP) of peste des petits ruminants (PPR) virus in the baculovirus system (PPRV-rBNP) and its potential application as a diagnostic antigen in ELISA for diagnosis of PPR in sheep and goats. The PPRV N-terminal immunogenic region (1-266 aa) of the NP coding sequence was amplified and cloned into the pFastBac HT A vector. The PPRV-rBNP with a molecular weight of ~30 kDa was expressed in an insect cell system using generated recombinant baculovirus through Bac-to-Bac® Baculovirus Expression System. The crude PPRV-rBNP or Ni-NTA affinity-purified NP was characterized by SDS-PAGE and immunoblot using standard PPRV-specific sera. The PPRV-rBNP reacted well with PPRV anti-N specific monoclonal and polyclonal antibodies and PPRV-specific antiserum, suggesting that the expressed PPRV-rBNP is in its native form. The crude PPRV-rBNP as a diagnostic antigen was evaluated either as a coating antigen or standard positive control antigen in the Avidin-Biotin ELISA using the known standard panel reagents. The results showed that the expressed PPRV-rBNP can be an alternative diagnostic antigen to E. coli expressed recombinant PPRV-NPN and the utility of PPRV-rBNP avoids the need to use live PPRV antigen in the diagnostic ELISA. Hence, this allows scope in the future for large-scale field application of the recombinant antigen-based assays for diagnosis/surveillance and monitoring of PPR at the eradication as well as post-eradication phases in endemic or non-endemic countries.

Comparative diagnostic efficacy of Avidin-Biotin recombinant nucleoprotein competitive ELISA for serosurveillance and monitoring of peste des petits ruminants in sheep and goats

In this study extensive evaluation of Avidin-Biotin recombinant nucleoprotein competitive ELISA (ABrC-ELISA) was carried out by mass screening of a large number of sera to make use of this assay for serosurveillance and seromonitoring of peste des petits ruminants (PPR) in sheep and goats to evaluate its diagnostic efficacy value and strengthen findings associated with the assay. The recombinant PPR virus (PPRV) nucleoprotein was over-expressed in E. coli, Ni-NTA affinity-purified, and characterized and used as coating diagnostic antigen in ABrC-ELISA, and evaluated using the field sera from animals. On evaluation of the diagnostic performance or efficacy of this assay using the pre-vaccinated and post-vaccinated sera of sheep and goats (n = 1437), the ABrC-ELISA showed a relative diagnostic sensitivity of 87.2% (95% CI: 84.1-90%) and diagnostic specificity of 92.0% (95% CI: 90-93.7%), against well-established existing indigenous H protein-specific PPR competitive ELISA kit with an accuracy of 90.1% (95% CI: 88.5-91.7%) and good or substantial agreement of Cohen's Kappa value of 0.79 ± 0.017 SE (95% CI: 0.76 to 0.82). These findings suggest that the ABrC-ELISA is a potential additional diagnostic tool of a rapid, sensitive, and specific assay for the detection of the PPRV nucleoprotein antibodies in sera of sheep and goats. This PPR Ab Chek kit can be used extensively under field conditions for serosurveillance, and seromonitoring of PPR in sheep and goats at the eradication /post-eradication phase in disease-controlled countries or PPR non-enzootic countries.

Evaluation of diagnostic performance of H-based blocking ELISA for specific detection of peste des petits ruminants in domestic sheep, goats, cattle and camels

INTRODUCTION

Peste des petits ruminants virus (PPRV) causes a highly devastating disease of sheep and goats, peste des petits ruminants (PPR), which is targeted for global control and eradication by 2030. The serological diagnostic tool kits for accurate diagnosis of PPR have inherent strengths and weaknesses that require parallel validation and optimization across animal species. Thus, the objective of this study was to evaluate diagnostic performance of haemagglutinin based PPR blocking ELISA (HPPR- b-ELISA), that was developed by Africa Union Pan African Veterinary Vaccine Center for specific detection of anti- PPRV antibodies.

METHODS

In preliminarily investigation, diagnostic performance of the HPPR-b-ELISA®, commercial PPR competition ELISA (c-ELISA) and virus neutralization test (VNT) were compared for the detection of anti-PPRV antibodies in goats, sheep, cattle and camels.

RESULTS

The sensitivity and specificity of HPPR- b-ELISA® were 79.55 and 99.74%, respectively, compared to c-ELISA. The HPPR- b-ELISA® was in perfect agreement (κ = 0.86) with the c-ELISA in all sera collected from goats, sheep and cattle. There was almost perfect agreement between the species of goats (κ = 0.82) and sheep (κ = 0.98), while the agreement was substantial in cattle (κ = 0.78) and no agreement was observed in camels (κ = 0.00). Similarly, the sensitivity and specificity of the HPPR b-ELISA were 80 and 96.36%, respectively compared to VNT with almost perfect agreement in goats (κ = 0.83) and sheep (κ = 0.89), moderate in cattle (κ = 0.50) and none in camels (κ = 0.00).

CONCLUSION

Our study revealed that HPPR- b-ELISA is a suitable and valid method that can alternatively be used for screening and monitoring of PPR in sheep, goats and cattle except for camels.

Long term immunity against Peste Des Petits Ruminants mediated by a recombinant Newcastle disease virus vaccine

Peste des Petits Ruminants (PPR) is a highly contagious and often fatal disease of sheep and goats. Conventional live vaccines have been successfully used in endemic countries however, there are not completely safe and not allowing differentiation between vaccinated and infected animals (DIVA). In this study, a recombinant Newcastle disease virus (NDV) expressing the hemagglutinin of PPRV (NDV-PPRVH) was evaluated on small ruminants by serology response in sheep and goats, experimental infection in goats and immunity duration in sheep. The NDV-PPRVH vaccine injected twice at 28 days' interval, provided full protection against challenge with a virulent PPR strain in the most sensitive species and induced significant neutralizing antibodies. Immunological response in goats was slightly higher than sheep and the vaccine injected at 10^8.0 50 % egg infective dose/mL allowed anti-PPRV antibodies that lasted at least 12 months as shown by antibody response monitoring in sheep. The NDV vector presented a limited replication in the host and vaccinated animals remained negative when tested by cELISA based on PPRV nucleoprotein allowing DIVA. This recombinant vaccine appears to be a promising candidate in a free at risk countries and may be an important component of the global strategy for PPR eradication.

Development of Nanobodies Targeting Peste des Petits Ruminants Virus: The Prospect in Disease Diagnosis and Therapy

Simple Summary

Peste des petits ruminants virus (PPRV) causes a highly devastating disease, peste des petits ruminants (PPR) of sheep and goats, that threatens food security, small ruminant production, and the conservation of wild small ruminants. Current efforts are directed towards the global control and eradication of PPRV, an initiative of the World Organisation for Animal Health and Food and the Agriculture Organisation of the United Nations. A plethora of diagnostic tools for PPR were primarily developed for livestock. New innovative diagnostic tools are needed to detect PPRV in atypical hosts (e.g., Camelidae, Suidae, and Bovinae), in wildlife ecosystems, and in complex field situations. Recent studies confirmed that single-domain antigen binding fragments (nanobodies) derived from heavy-chain-only camelid antibodies have proven to be a powerful tool in diagnostics and therapeutics due to their unique properties, such as small size and strong antigen-binding affinity. Therefore, the main objective of this study was to generate PPRV-reactive nanobodies in order to set a pace for the development of diagnostic and possibly therapeutic nanobodies in the future. Initially, a strategy was developed whereby an alpaca was immunized with PPRV in order to raise an affinity-matured immune response, from which an immune nanobody library was constructed. Following phage display, nine nanobodies that specifically recognise PPRV were identified on enzyme-linked immunosorbent assay. This study has generated PPRV-reactive nanobodies and have significant implications in the development of cost-effective diagnostic tools in context with the planned eradication of PPR in the world.

Abstract

Peste des petits ruminants virus (PPRV) causes a highly devastating disease, peste des petits ruminants (PPR) of sheep and goats, that threatens food security, small ruminant production, and the conservation of wild small ruminants in many developing countries, especially in Africa. Robust serological and molecular diagnostic tools are available to detect PPRV infection, but they were mainly developed for domestic sheep and goats. The presence of a wide host range for PPRV does present serological diagnostic challenges. New innovative diagnostic tools are needed to detect PPRV in atypical hosts (e.g., Camelidae, Suidae, and Bovinae), in wildlife ecosystems and in complex field situations. Interestingly, single-domain antigen binding fragments (nanobodies) derived from heavy-chain-only camelid antibodies have emerged as a new hope in the development of accurate, rapid, and cost-effective diagnostic tools in veterinary and biomedical fields that are suitable for low-income countries. The main objective of this study was to construct an immune nanobody library to retrieve PPRV-reactive nanobodies that enable the development of diagnostic and therapeutic nanobodies in the future. Here, a strategy was developed whereby an alpaca (Vicugna pacos) was immunized with a live attenuated vaccine strain (PPRV/N/75/1) to raise an affinity-matured immune response in the heavy-chain-only antibody classes. The nanobody gene repertoire was engineered in pMECS-GG phagemid, whereby a ccdB gene (encoding a lethal protein) was substituted by the nanobody gene. An immune nanobody library with approximately sixty-four million independent transformants was constructed, of which 100% contained an insert with the proper size of nanobody gene. Following phage display and biopanning, nine nanobodies that specifically recognise completely inactivated PPRV were identified on enzyme-linked immunosorbent assay. They showed superb potency in rapidly identifying PPRV, which is likely to open a new perspective in the diagnosis and possible treatment of PPR infection.

The influence of intranasal peste des petits ruminants (PPR) vaccine administration alone or with phytogenic mucoadhesive delivery system on PPR outbreak outcomes in goats

This study reports the influence of peste des petits ruminants (PPR) vaccination on the clinico-pathological outcomes of PPR in the face of an outbreak. Twenty-two West African dwarf goats procured for a different study started showing early signs of PPR during acclimatization. In response, PPR vaccine was administered either intranasally with phytogenic mucoadhesive gum (Group A; n = 6) or without gum (Group B; n = 6); subcutaneously (Group C; n = 6) or not vaccinated (Group D; n = 4) and studied for 21 days. The clinical scores, hematology, serology and pathology scores were evaluated. Clinical signs of PPR were present in all groups, presenting a percentage mortality of 33%; 33%; 64% and 100% for Groups A, B, C, and D, respectively. Polycythemia and mild leukopenia were observed in all groups, and all animals were seropositive by day 7 post-vaccination. The lung consolidation scores were low in Groups A and B, compared to Group C. Histopathological lesions consistent with PPR was observed in the lymphoid organs, gastrointestinal tract, and lungs with the presence of PPR antigen as detected by immunohistochemistry. The findings suggest that intranasal vaccination with or without mucoadhesive gum may influence the outcome of PPR infection more than the subcutaneous route in the face of an outbreak.

Intranasal Peste des petits ruminants virus vaccination of goats using Irvingia gabonensis gum as delivery system: hematological and humoral immune responses

Peste des petits ruminants (PPR) in Africa continues to defy conventional vaccinational approaches aimed at its control. There is need for route modification and immunopotentiation of the current vaccination methods, using easily affordable materials. This study evaluates the immunomodulatory potential of Irvingia gabonensis (IG) seed gum extract for intranasal PPR vaccination in goats using attenuated Nigeria 75/1 PPR vaccine. Twenty West African dwarf goats were divided into four groups (n=5). Group 1 was vaccinated intranasally using IG gum as vehicle; Group 2 was vaccinated intranasally without the gum; Group 3 via subcutaneous injection while Group 4 was not vaccinated. Hematology and Serum IgG levels were assessed weekly for 28 days post vaccination (dpv). H-PPR bELISA detected antibodies against PPR by 7th dpv, peaking by 21st dpv with mean percentage inhibitions of 78.2%; 69.6%; 87.0% and 0% in Groups 1, 2, 3 and 4, respectively. Also, significantly lower neutrophil to lymphocyte ratio (P<0.05) were observed by 14th dpv to 28th dpv in the vaccinated groups. The findings of this study show that the use of I. gabonensis seed gum extract for mucoadhesive intranasal PPR vaccine delivery has an immunomodulatory effect on the systemic immune response following PPR intranasal vaccine administration.

Field serological investigation for peste des petits ruminants, foot-and-mouth disease, and bluetongue diseases in illegally introduced animals in Egypt

AIM

In this study, laboratory scoping on the viruses that cause peste des petits ruminants (PPR), bluetongue (BT), and foot-and-mouth disease (FMD) was performed to evaluate the current status of animals illegally introduced into Egypt. This study aims to help control these infectious illnesses and tries to prevent the introduction of other strains of these three viruses to Egypt, as these illnesses spread quickly if not controlled.

MATERIALS AND METHODS

In the year 2018, 62 serum samples were collected and serologically tested through competitive enzyme-linked immunosorbent assays (ELISA) kits to detect antibodies against PPR, BT, and FMD, which are three important transboundary infectious illnesses.

RESULTS

The results indicated that 60 out of 62 serum samples were positive for PPR antibodies (96.7%), 31 out of 62 were positive for FMD antibodies (50%), and 59 out of 62 serum samples were positive for BT antibodies (95%).

CONCLUSION

This study revealed that PPR, FMD, and BT can be introduced into Egypt through the illegal introduction of sheep and goat from neighboring countries. Laboratory diagnostic abilities should be improved for the early detection and control of these illnesses.

Sentinel surveillance of selected veterinary and public health pathogens in camel population originating from Southern Punjab province, Pakistan

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Camels are susceptible to a wide range of infectious diseases with varying rate of morbidity and mortality.

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Blutongue, peste des petits ruminants and brucellosis are prevalent among camels in southern part of the Punjab provinvce, Pakistan.

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Genome corresponding to Brucella abortus and multiple serotypes of bluetongue were detected among camels.

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Camels should be included for disease control interventions reltaed to brucellosis, blutongue and PPR from their endemic setting worldwide.

An extended range of host susceptibility including camel has been evidenced for some of the important veterinary and public health pathogens, such as brucellosis, peste des petits ruminants (PPR) and bluetongue (BT). However, in disease endemic settings across many parts of the globe, most of the disease control interventions accounts for small and large ruminants, whereas unusual hosts and/or natural reservoirs, such as camels, remain neglected for disease control measures including routine vaccination. Such a policy drawback not only plays an important role in disease epizootiology particularly in settings where disease is endemic, but also serves an obstacle in disease control and subsequent eradication in future. With this background, using pre-validated ELISA and molecular assays [multiplex PCR, reverse transcriptase (RT)-PCR and real-time (rt)-PCR], we conducted a large-scale pathogen- and antibody-based surveillance for brucellosis, peste des petits ruminants and bluetongue in camel population (n = 992) originating from a wide geographical region in southern part of the Punjab province, Pakistan. Varying in each of the selected districts, the seroprevalence was found to be maximum for bluetongue [n = 697 (70.26%, 95% CI: 67.29–73.07)], followed by PPR [n = 193 (19.46%, 95% CI: 17.07–22.09)] and brucellosis [n = 66 (6.65%, 95% CI: 5.22–8.43)]. Odds of seroprevalence were more significantly associated with pregnancy status (non-pregnant, OR = 2.23, 95% CI: 1.86–5.63, p<0.01), farming system (mixed-animal, OR = 2.59, 95% CI: 1.56–4.29, p<0.01), breed (Desi, OR = 1.97, 95% CI: 1.28–4.03, p<0.01) and farmer education (illiterate, OR = 3.17, 95% CI: 1.45–6.93, p<0.01) for BTV, body condition (normal, OR = 3.54, 95% CI: 1.92–6.54, p<0.01) and breed (Desi, OR = 2.19, 95% CI: 1.09–4.40, p<0.01) for brucellosis, and feeding system for PPR (grazing, OR = 2.75, 95% CI: 1.79–4.22, p<0.01). Among the total herds included (n = 74), genome corresponding to BT virus (BTV) and brucellosis was detected in 14 (18.92%, 95 CI: 11.09–30.04) and 19 herds (25.68%, 95% CI: 16.54–37.38), respectively. None of the herds was detected with genome of PPR virus (PPRV). Among the positive herds, serotype 1, 8 and 11 were detected for BTV while all the herds were exclusively positive to B. abortus. Taken together, the study highlights the role of potential disease reservoirs in the persistence and transmission of selected diseases in their susceptible hosts and, therefore, urges necessary interventions (e.g., inclusion of camels for vaccine etc.) for the control of diseases from their endemic setting worldwide.

Evaluation of mucoadhesive property and the effect of Boswellia carteri gum on intranasal vaccination against small ruminant morbillivirus infection (PPR)

A study was conducted to evaluate mucoadhesive property and immunomodulatory effect of phytogenic gums from Boswellia frereana, Boswellia carteri andCommiphora myrrha on intranasal Peste des petits ruminants (PPR) vaccination in goats and sheep in an ex-vivo and in-vivo situations. Plant gums were purified, dried and compressed into 500gm tablets. Modified shear stress measurement technique was used on freshly excised trachea and intestine tissues of goat to measure peak adhesion time. Forty eight animals (24 goats and 24 sheep) were divided into eight groups (of 3 goats and 3 sheep) and immunized intranasally with gum-vaccine combinations in two ratios (1:1, 1:2). Antibody against PPR virus was measured on day 14, 28, 42 and 56 post vaccination using H-based PPR bELISA. The peak adhesion time of the different gums was transient. PPR virus antibodies were detected in all immunized goats and sheep but not in unvaccinated control. The best percentage inhibition was recorded for Boswellia carteri-vaccine combination group at a ratio of 1:1. Administration of Boswellia carteri-PPR vaccine combination through intranasal or subcutaneous route, elicited similar antibody titre, implying that the intranasal route may be used as a non-invasive alternative delivery in PPR vaccination of small ruminants.

Paradigm shift in the diagnosis of peste des petits ruminants: scoping review

Peste des petits ruminants virus causes a highly contagious disease, which poses enormous economic losses in domestic animals and threatens the conservation of wild herbivores. Diagnosis remains a cornerstone to the Peste des petits ruminants Global Control and Eradication Strategy, an initiative of the World Organisation for Animal Health and the Food and Agriculture Organisation. The present review presents the peste des petits ruminants diagnostic landscape, including the practicality of commercially available diagnostic tools, prototype tests and opportunities for new technologies. The most common peste des petits ruminants diagnostic tools include; agar gel immunodiffusion, counter-immunoelectrophoresis, enzyme-linked immunosorbent assays, reverse transcription polymerase chain reaction either gel-based or real-time, reverse transcription loop-mediated isothermal amplification, reverse transcription recombinase polymerase amplification assays, immunochromatographic lateral flow devices, luciferase immunoprecipitation system and pseudotype-based assays. These tests vary in their technical demands, but all require a laboratory with exception of immunochromatographic lateral flow and possibly reverse transcription loop-mediated isothermal amplification and reverse transcription recombinase polymerase amplification assays. Thus, we are proposing an efficient integration of diagnostic tests for rapid and correct identification of peste des petits ruminants in endemic zones and to rapidly confirm outbreaks. Deployment of pen-side tests will improve diagnostic capacity in extremely remote settings and susceptible wildlife ecosystems, where transportation of clinical samples in the optimum cold chain is unreliable.

Peste des petits ruminants virus hemagglutinin (H) induces lysosomal degradation of host cyclophilin A to facilitate viral replication

Peste des petits ruminants virus (PPRV) is a highly contagious disease that affects sheep and goats. To better understand PPRV replication and virulence, cyclophilin A (CypA), a multifunctional goat host protein, was selected for further studies. CypA has been reported to inhibit or facilitate viral replication. However, the precise roles of CypA during PPRV infection remain unclear. Our data show for the first time that CypA suppressed PPRV replication by its PPIase activity, and PPRV infection decreased CypA protein levels. Detailed analysis revealed that PPRV H protein was responsible for the reduction of CypA, which was dependent on the lysosome pathway. No interaction was identified between H and CypA. Furthermore, the 35-58 region of H was essential for the reduction of CypA. In conclusion, our findings identify the antiviral role of CypA against PPRV and provide key insights into how PPRV H protein antagonizes host antiviral response.

Peste des petits ruminants pathogenesis on experimental infected goats by the Moroccan 2015 isolate

BACKGROUND

Peste des petits ruminants (PPR) is a viral disease of major economic importance on small ruminants. Goats are usually known to be more susceptible to the disease. Infection chronology, virus circulation, and the disease early detection need to be better understood. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of goats using a lineage IV virus, the most dominant in the world originated from Asia. PPRV infection was experimentally induced in 4 six-month-old goats by intra-nasal and intravenous route of cell virus suspension and from infectious mashed tissue. The clinical signs were observed and goats were euthanized at predetermined clinical score level for post-mortem examinations and PPRV detection by RT-PCR. Clinical signs of infection were present, pyrexia, serous-mucopurulent nasal discharges, coughing, diarrhea and asthenia, for both cell virus suspension and infectious mashed tissue. PPRV genome was highly detected in swabs and tissues with clinical signs dominated by pulmonary attack and digestive symptoms secondary.

RESULTS

Results of this study indicates that PPRV is an invasive infection in animals that in a short period, less than 10 days, invade all vital organs. On live animals, early diagnostic may be easily done on lacrimal and rectal swabs.

CONCLUSION

The experimental PPRV-infection model using the cell virus suspension is suitable for vaccine evaluation as a standard model.

Peste des Petits Ruminants Virus Surveillance in Domestic Small Ruminants, Mozambique (2015 and 2017)

Peste des Petits Ruminants (PPR), a transboundary animal disease affecting mainly goats and sheep is caused by a morbillivirus and threatens food security and livelihoods as morbidity and mortality rates can reach 90%. There are no records of PPR in Mozambique, but the disease situation in Tanzania and the ability of PPR virus to rapidly spread across countries constitute a high risk for about 4.7 million goats and sheep in Mozambique. A total of 4,995 goats and sheep were sampled in several provinces during 2015 and 2017 to assess the status of PPR virus (PPRV) in Mozambique and to contribute to surveillance along the border with Tanzania. The sera were screened for anti-PPRV antibodies using a commercial PPR competition ELISA (c-ELISA) and the haemagglutinin based PPR blocking ELISA (HPPR-bELISA). The swabs were tested using one-step RT-PCR for detection of PPRV RNA. The overall percentage of animals with anti-PPRV antibodies by c-ELISA, was 0.46% [0.30–0.70]. However, all the sera positive on c-ELISA were confirmed to be negative by the HPPR-bELISA. Considering that all the swabs were negative for detection of PPRV, no clinical cases were observed during passive surveillance and active sampling, and no symptoms were reported, these results suggest that PPRV is not present in Mozambique.

Development and Evaluation of Epitope-Blocking ELISA for Detection of Antibodies against Contagious Caprine Pleuropneumonia in Goat Sera

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.

Progress to Control and Eradication of Peste des Petits Ruminants in the Southern African Development Community Region

In southern Africa, small ruminants are an important source of nutrition and income to resource-poor small holder farmers. After spreading from West to Central and Eastern Africa, peste des petits ruminants (PPR) emerged in the United Republic of Tanzania in 2008 and has since been reported in Angola, the Democratic Republic of the Congo, and the Comoros. The disease can cause considerable morbidity and mortality in naïve sheep and goat populations and severely impact rural livelihoods, particularly those of women. Gaps in the knowledge of PPR epidemiology still exist, particularly around the role of small-ruminant movement and the role of the abundant wildlife in southern Africa. The capacity of veterinary services to undertake surveillance and control PPR is heterogeneous within the region, with vaccination being limited. The Pan African strategy for the control and eradication of PPR mirrors the Global Strategy and provides the framework for the Southern African Development Community (SADC) region to meet the 2030 goal of eradication. Five countries and one zone within Namibia are officially PPR free according to OIE Standards. Most countries have developed national strategies for the control and eradication of PPR. To strengthen national and regional PPR eradication programme goals, there is a need for a regional risk-based surveillance adapted to infected, high-risk and lower-risk countries that will enable targeted and efficient control, rapid response to incursions and prevention of spread as well as improved preparedness. Continued international and national support will be necessary including laboratory diagnostics and enhancing surveillance capacity to prevent further spread southwards on the continent.

Epidemiological Survey of Peste des Petits Ruminants in Ethiopia: Cattle as Potential Sentinel for Surveillance

Peste des petits ruminants (PPR) is a highly contagious viral disease of small ruminants; it emerged in countries previously free of the disease following the eradication of rinderpest. PPR is classified by international organizations as the next priority animal disease for global eradication campaign. Assessment of the local situations is the first step in the eradication efforts. The objective of this study was to investigate and compare the seroprevalence of PPR in cattle, sheep, and goats under two livestock production systems in Ethiopia: North Shewa zone of Amhara region represents a highland sedentary life style characterized by mixed livestock-crop production system; Zone Three of Afar region represents a lowland nomadic life style characterized by pastoral livestock production system. N-competitive ELISA PPR test was performed on sera from 2,993 animals ≥6 months old sampled at watering and grazing points. Multivariable logistic regression models comparing the seropositivity between the two production systems were built by classifying doubtful results as positive, negative, or excluding them from the data. The odds ratio (OR) comparing overall PPR seroprevalence in the sedentary North Shewa Zone compared to the nomadic Zone Three ranged from 19 to 27 (P < 0.001), depending on how doubtful results were classified, which contrasts with what has been reported in the literature. This is not likely to be related solely to vaccination, since seroprevalences in cattle and small ruminants were similarly high or low in the respective zones (0-4% for Zone Three and 20-40% for North Shewa Zone), and cattle were not likely to be vaccinated. The OR of seropositivity for goats compared to cattle ranged from 1.9 [95% confidence interval (CI): 1.3-2.7; P < 0.001] to 2.2 (95% CI: 1.5-3.1; P < 0.001) when doubtful results were excluded or classified as negative, respectively. When doubtful results were classified as positive, association between seropositivity and animal species was not significant (P > 0.05). Our results suggest to further investigate cattle as sentinel animals for PPR surveillance.

Experimental infection of dromedary camels with virulent virus of Peste des Petits Ruminants

Peste des Petits Ruminants Virus (PPRV) causes a severe contagious disease of sheep and goats and has spread extensively in last years through Asia and Africa. PPRV, known to infect exclusively small ruminants, has been recently reported in camels in Iran and Sudan. Reported clinical symptoms are similar to those observed in small ruminants, fatality rate still unknown. However most of the authors reported seropositive camels without clinical signs. Camel sensitivity to PPRV is still controversial and more investigation need to be performed. In this study, we tested camel susceptibility by an experimental infection using a virulent PPRV strain belonging to lineage IV. Young dromedary camels were infected intravenously and observed one month for clinical symptoms. Viraemia and virus secretion charge in swabs were evaluated by PCR. Seroconversion was assessed by ELISA and virus neutralisation test. Infected animals did not manifest any clinical symptoms of the disease and no virus was detected in secretions. Seroconversion was observed from day 14 post infection.

Detection and molecular characterization of Peste des Petits Ruminants virus from outbreaks in Burundi, December 2017-January 2018

In December 2017, Peste des Petits Ruminants (PPR) emerged in Burundi (East Africa) and rapidly spread to five provinces (Gitega, Kirundo, Mwaro, Muramvya and Karuzi) in the country, causing severe disease and killing more than 4,000 goats in the province of Gitega alone. An initial outbreak investigation was conducted in December 2017 by the Burundi Government Veterinary Services and samples were collected for laboratory confirmation. A competitive Enzyme Linked Immuno-Sorbent Assay (cELISA: Chinese Patent No. ZL201210278970.9) supplied by the Lanzhou Veterinary Research Institute was used to test 112 sera and results showed around 37.5% positive samples. This high level of PPR positive sera in an animal population where PPR infection and vaccination had not been previously reported indicated the exposure of the animals to PPRV. Subsequently in January 2018, the laboratory tests conducted at the African Union-Pan African Veterinary Vaccine Centre (AU-PANVAC) laboratories following a joint investigative mission by the African Union-Interafrican Bureau for Animal Resources (AU-IBAR), AU-PANVAC and the East African Community (EAC) confirmed the presence of PPR in Burundi. Samples tested by conventional RT-PCR indicated the presence of the PPR virus (PPRV). Confirmatory isolation of the virus was also performed. Phylogenetic analysis revealed that the virus belongs to lineage III and shows a close relationship with PPRV isolates from Kenya in 2011 and Uganda in 2012. A possible explanation for the outbreaks of PPR in Burundi between December 2017 and February 2018 is presented.