Peste des Petits Ruminants Virus Infection at the Wildlife-Livestock Interface in the Greater Serengeti Ecosystem, 2015-2019

Structure, Attachment and Transmembrane Internalisation of Peste Des Petits Ruminants Virus

Peste des petits ruminants virus (PPRV), a single-stranded negative-sense RNA virus with an envelope, belongs to the Morbillivirus in the Paramyxoviridae family and is prevalent worldwide. PPRV infection causes fever, stomatitis, diarrhoea, pneumonia, abortion and other symptoms in small ruminants, with a high mortality rate that poses a significant threat to the sustainability and productivity of the small ruminant livestock sector. The PPRV virus particles have a diameter of approximately 400-500 nm and are composed of six structural proteins: nucleocapsid protein (N), phosphoprotein (P), envelope matrix protein (M), fusion protein (F), haemagglutinin protein (H) and large protein (L). Each protein has a distinct role in the virus's life cycle. Although the life cycle activities of PPRV have been widely reported, they are still limited. Research has demonstrated that PPRV has distinct adhesion factors on various cell surfaces, such as the epithelial cell adhesion factor nectin-4 or the lymphocyte adhesion factor SLAM. After attaching to the cell, the F and H proteins on the PPRV membrane interact with each other, resulting in a conformational change in the F protein. This change allows the F protein to enter the cell through direct fusion with the host cell membrane. The virus enters the host cell via the outer vesicle endocytosis strategy and replicates and proliferates through the role of caveolin, actin, dynein and cholesterol on the host cell membrane. This review summarises the viral structure, attachment mechanism and transmembrane internalisation mechanism of PPRV. The aim of this review is to provide theoretical support for the development of PPRV inhibitors and the prevention and control of PPR.

First Incidence of Peste des Petits Ruminants Virus in Cervidae Family from State Zoo of Assam, India

The present study aimed to investigate the episodes of per-acute mortality due to peste des petits ruminants (PPR) that resulted in the death of 30 animals of different species of cervids, namely, barking deer, four-horned antelope, hog deer, thamin, and mouse deer in the State Zoo of Assam, a northeastern state of India. The affected animals showed no to limited clinical signs. However, the necropsy and histopathological findings were highly suggestive of PPR virus (PPRV) infection observed in domestic small ruminants. Representative tissue samples were screened for the presence of PPRV along with blue tongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) using RT-PCR or RT-qPCR and were found to be positive for PPRV. Considering the sudden outbreak of PPR in captive cervids, we sought to determine the role of domestic goats as the potential spillover host. To verify that, archived tissue samples of domestic goats collected during PPRV outbreaks in nearby localities and slaughtered goats used as meat for Carnivorous animals in the State Zoo were also screened and found to be positive for PPRV in RT-PCR. Phylogenetic analysis based on the Nucleocapsid (N) protein gene of PPRV from infected cervids, domestic goats, and goat meat revealed the virus to be of Lineage IV origin. Our findings provide evidence of probable spillover of PPRV from domestic goats to captive endangered cervids and circulation of Lineage IV PPRV strains among the small-ruminant population of this region.

Prediction of the Potential Host of Peste Des Petits Ruminants Virus by the Least Common Amino Acid Pattern in SLAM Receptor

Peste-des-Petits Ruminants Virus (PPRV) causes a highly contagious and severe infectious disease known as Peste-des-Petits Ruminants (PPR), resulting in significant mortality in both domestic and wild ruminants. An in-depth understanding of the molecular relationship between PPRV and susceptible hosts is essential for the prevention of PPR. The signaling lymphocytic-activation molecule (SLAM) acts as a key receptor in susceptible host species, mediating interactions with PPRV and triggering PPR in ruminants. This study offers an in-depth analysis of PPRV-susceptible host species as well as the identified SLAM amino acid sequences to date. Investigation reveals that nine families-Bovidae, Camelidae, Cervidae, Elephantidae, Suidae, Felidae, Canidae, Muridae, and Ceratopogonidae-have been affected by PPRV infection. Furthermore, a bioinformatics-based approach was proposed to screen the least common amino acid patterns (LCAP) in important SLAM receptor regions of known PPRV-susceptible species. Research findings reveal that 14 least common amino acid sites (LCAS) in SLAM amino acid sequences (I61, I63, S60, S70, K76, K78, I79, S81, L82, E123, N125, S127, V128, and F131) exhibit a prevalent similarity to LCAP across all known susceptible species. Comparative analysis of these 14 LCAP with SLAM nucleotide sequences from unknown susceptible ruminants to identify species at heightened risk of PPRV. In the result, 48 species from 20 different families across six orders were at potential risk of being infected with PPRV. This exploration suggests the feasibility of assessing potential hosts at high risk of PPRV infection through the LCAS screening technique. Moreover, it offers a means to anticipate and issue warnings regarding the likelihood of interspecies transmission. In conclusion, this study integrates molecular biology and bioinformatics, shedding light on PPRV infection dynamics and paving the way for predictive strategies to prevent the spread of this devastating disease among ruminant populations.

An Integrated Ecological Niche Modelling Framework for Risk Mapping of Peste des Petits Ruminants Virus Exposure in African Buffalo (Syncerus caffer) in the Greater Serengeti-Mara Ecosystem

Peste des petits ruminants (PPR) is a highly contagious viral disease of small ruminants that threatens livelihoods and food security in developing countries and, in some cases, wild ungulate species conservation. The Greater Serengeti-Mara Ecosystem (GSME) encompasses one of the major wildlife populations of PPR virus (PPRV)-susceptible species left on earth, although no clinical disease has been reported so far. This study aimed to gain further knowledge about PPRV circulation in the GSME by identifying which factors predict PPRV seropositivity in African buffalo (Syncerus caffer). Following an ecological niche modeling framework to map host-pathogen distribution, two models of PPRV exposure and buffalo habitat suitability were performed using serological data and buffalo censuses. Western Maasai Mara National Reserve and Western Serengeti National Park were identified as high-risk areas for PPRV exposure in buffalo. Variables related to wildlife-livestock interaction contributed to the higher risk of PPRV seropositivity in buffalo, providing supportive evidence that buffalo acquire the virus through contact with infected livestock. These findings can guide the design of cost-effective PPRV surveillance using buffalo as a sentinel species at the identified high-risk locations. As more intensive studies have been carried out in Eastern GSME, this study highlights the need for investigating PPRV dynamics in Western GSME.

Effect of epidemic diseases on wild animal conservation

Under the background of global species extinction, the impact of epidemic diseases on wild animal protection is increasingly prominent. Here, we review and synthesize the literature on this topic, and discuss the relationship between diseases and biodiversity. Diseases usually reduce species diversity by decreasing or extinction of species populations, but also accelerate species evolution and promote species diversity. At the same time, species diversity can regulate disease outbreaks through dilution or amplification effects. The synergistic effect of human activities and global change is emphasized, which further aggravates the complex relationship between biodiversity and diseases. Finally, we emphasize the importance of active surveillance of wild animal diseases, which can protect wild animals from potential diseases, maintain population size and genetic variation, and reduce the damage of diseases to the balance of the whole ecosystem and human health. Therefore, we suggest that a background survey of wild animal populations and their pathogens should be carried out to assess the impact of potential outbreaks on the population or species level. The mechanism of dilution and amplification effect between species diversity and diseases of wild animals should be further studied to provide a theoretical basis and technical support for human intervention measures to change biodiversity. Most importantly, we should closely combine the protection of wild animals with the establishment of an active surveillance, prevention, and control system for wild animal epidemics, in an effort to achieve a win-win situation between wild animal protection and disease control.

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.

Genes, inflammatory response, tolerance, and resistance to virus infections in migratory birds, bats, and rodents

Normally, the host immunological response to viral infection is coordinated to restore homeostasis and protect the individual from possible tissue damage. The two major approaches are adopted by the host to deal with the pathogen: resistance or tolerance. The nature of the responses often differs between species and between individuals of the same species. Resistance includes innate and adaptive immune responses to control virus replication. Disease tolerance relies on the immune response allowing the coexistence of infections in the host with minimal or no clinical signs, while maintaining sufficient viral replication for transmission. Here, we compared the virome of bats, rodents and migratory birds and the molecular mechanisms underlying symptomatic and asymptomatic disease progression. We also explore the influence of the host physiology and environmental influences on RNA virus expression and how it impacts on the whole brain transcriptome of seemingly healthy semipalmated sandpiper (Calidris pusilla) and spotted sandpiper (Actitis macularius). Three time points throughout the year were selected to understand the importance of longitudinal surveys in the characterization of the virome. We finally revisited evidence that upstream and downstream regulation of the inflammatory response is, respectively, associated with resistance and tolerance to viral infections.

Peste Des Petits Ruminants Screening and Diagnostic Tests in African Wildlife in the Context of Rinderpest Eradication (1994-2007)

Peste des petits ruminants (PPR) virus causes a major disease in domestic and wild small ruminants. Understanding the role of wildlife in PPR virus ecology is important for PPR control and its eradication targeted worldwide in 2030. Developing diagnostic tools that provide reliable data for PPR detection in wildlife will help monitor wild populations for PPR and support the eradication program. We analyze a continental-scale dataset from African free-ranging wild ungulates (n = 2570) collected between 1994 and 2007. A Bayesian model estimated the performance of ELISA tests against PPR and rinderpest and their prevalence in African buffalo. The H- and N-ELISA tests used, not initially developed for wildlife, showed poor sensitivities for the detection of PPR antibodies in African buffalo. The estimations of PPR antibody prevalence derived from the results of these tests for animals presumably not exposed or potentially exposed to PPR were uncertain. Thus, poor performances of these PPR serological tests in wildlife would not allow robust estimations of PPR antibody prevalence in African buffalo and would be extremely speculative in non-buffalo wild ungulate species. We recommend that current and new tests be validated for wildlife hosts to provide sufficient sensitivity and specificity of detection and a diagnostic protocol be developed for PPR wildlife research.

Novel and classical morbilliviruses: Current knowledge of three divergent morbillivirus groups

Currently, seven species of morbillivirus have been classified. Six of these species (Measles morbillivirus, Rinderpest morbillivirus, Small ruminant morbillivirus, Canine morbillivirus, Phocine morbillivirus, and Cetacean morbillivirus) are highly infectious and cause serious systemic diseases in humans, livestock, domestic dogs, and wild animals. These species commonly use the host proteins signaling lymphocytic activation molecule (SLAM) and nectin-4 as receptors, and this usage contributes to their virulence. The seventh species (Feline morbillivirus: FeMV) is phylogenetically divergent from the six SLAM-using species. FeMV differs from the SLAM-using morbillivirus group in pathogenicity and infectivity, and is speculated to use non-SLAM receptors. Recently, novel species of morbilliviruses have been discovered in bats, rodents, and domestic pigs. Because the ability to use SLAM and nectin-4 is closely related to the infectivity and pathogenicity of morbilliviruses, investigation of the potential usage of these receptors is useful for estimating infectivity and pathogenicity. The SLAM-binding sites in the receptor-binding protein show high similarity among the SLAM-using morbilliviruses. This feature may help to estimate whether novel morbillivirus species can use SLAM as a receptor. A novel morbillivirus species isolated from wild mice diverged from the classified morbilliviruses in the phylogenetic tree, forming a third group separate from the SLAM-using morbillivirus group and FeMV. This suggests that the novel rodent morbillivirus may exhibit a different risk from the SLAM-using morbillivirus group, and analyses of its viral pathogenicity and infectivity toward humans are warranted.

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.

Peste des Petits Ruminants in Central and Eastern Asia/West Eurasia: Epidemiological Situation and Status of Control and Eradication Activities after the First Phase of the PPR Global Eradication Programme (2017–2021)

Simple Summary

Peste des petits ruminants (PPR) is a highly contagious viral disease of domestic and wild small ruminants. The disease is endemic to large parts of Africa, the Middle East and Asia and causes severe socioeconomic losses, especially in developing countries reliant on small ruminant value chains. Currently, PPR is the only animal disease targeted by the Global Eradication Programme (PPR GEP), which aims to eradicate the disease by 2030. Following the end of the first five-year phase of the PPR GEP, the goal of this review is to provide an update on the status of the eradication progress in one of the nine regions targeted for coordinated action in the PPR Global Control and Eradication Strategy, denominated Central Asia/West Eurasia. In addition to the original nine countries, regional meetings and activities have involved four additional countries based on shared epidemiological features, which are also reviewed here. The considered area spans from Eastern Europe to East Asia and features remarkable variability in terms of both PPR presence and enacted control efforts. The achievements and constraints encountered at regional and national levels are discussed, thus providing useful data for tailoring the next steps of the eradication programme to the peculiarities of the region.

Abstract

Peste des petits ruminants (PPR) is a highly contagious infectious disease of small ruminants caused by peste des petits ruminants virus (PPRV). PPR poses a significant threat to sheep and goat systems in over 65 endemic countries across Africa, the Middle East and Asia. It is also responsible for devastating outbreaks in susceptible wildlife, threatening biodiversity. For these reasons, PPR is the target of the Global Eradication Programme (PPR GEP), launched in 2016, which is aimed at eradicating the disease by 2030. The end of the first five-year phase of the PPR GEP (2017–2021) provides an ideal opportunity to assess the status of the stepwise control and eradication process. This review analyses 13 countries belonging to Eastern Europe, Transcaucasia, and Central and East Asia. Substantial heterogeneity is apparent in terms of PPR presence and control strategies implemented by different countries. Within this region, one country is officially recognised as PPR-free, seven countries have never reported PPR, and two have had no outbreaks in the last five years. Therefore, there is real potential for countries in this region to move forward in a coordinated manner to secure official PPR freedom status and thus reap the trade and socioeconomic benefits of PPR eradication.

Expansion in host dynamics of peste des petits ruminants: Potential attribute of outbreaks in disease-endemic settings

Since the first case report in 1942, the peste-des-petits-ruminants virus (PPRV) has been causing infection in a wide range of susceptible hosts, particularly in disease-endemic regions. In the last 40 years, various reports highlighted the evidence of disease and viral genome in around 46 animal species from nine diverse families, including Bovidae, Cervidae, Camelidae, Suidae, Canidae, Felidae, Muridae, and Elephantidae. This evidence of clinical and/ or subclinical infection and the presence of the virus in an extended range of susceptible hosts emphasizes the cross-species transmission that remains a significant obstacle to effective control, particularly in disease-endemic regions. Therefore, a better understanding of virus transmission, host susceptibility, and epidemiological investigation of the disease is crucial to achieving the goals of efficient disease control and eradication programs initiated by OIE and FAO in various diseases-endemic regions. Nevertheless, the propensity of PPRV to inter- and intra-transmission may be a possible constraint in disease control strategies in terms of the new outbreak with the involvement of unusual or novel hosts. Considering this aspect, we tried to summarize the scattered data on PPR in available information about the susceptibility of a wide range of wildlife species, large ruminants, camels, and unusual hosts.

Spatio-temporal cluster analysis and transmission drivers for Peste des Petits Ruminants in Uganda

Peste des Petits Ruminants (PPR) is a transboundary, highly contagious, and fatal disease of small ruminants. PPR causes global annual economic losses of between USD 1.5-2.0 billion across more than 70 affected countries. Despite the commercial availability of effective PPR vaccines, lack of financial and technical commitment to PPR control coupled with a dearth of refined PPR risk profiling data in different endemic countries has perpetuated PPR virus transmission. In Uganda, over the past five years, PPR has extended from north-eastern Uganda (Karamoja) with sporadic incursions in other districts /regions. To identify disease cluster hotspot trends that would facilitate the design and implementation of PPR risk-based control methods (including vaccination), we employed the space-time cube approach to identify trends in the clustering of outbreaks in neighbouring space-time cells using confirmed PPR outbreak report data (2007-2020). We also used negative binomial and logistic regression models and identified high small ruminant density, extended road length, low annual precipitation and high soil water index as the most important drivers of PPR in Uganda. The study identified (with 90 - 99% confidence) five PPR disease hotspot trend categories across subregions of Uganda. Diminishing hotspots were identified in the Karamoja region whereas consecutive, sporadic, new, and emerging hotspots were identified in central and southwestern districts of Uganda. Inter-district and cross-border small ruminant movement facilitated by longer road stretches and animal comingling precipitate PPR outbreaks as well as PPR virus spread from its initial Karamoja focus to the central and south-western Uganda. There is therefore urgent need to prioritize considerable vaccination coverage to obtain the required herd immunity among small ruminants in the new hotspot areas to block transmission to further emerging hotspots. Findings of this study provide a basis for more robust timing and prioritization of control measures including vaccination. This article is protected by copyright. All rights reserved.

Peste Des Petits Ruminants in Atypical Hosts and Wildlife: Systematic Review and Meta-Analysis of the Prevalence between 2001 and 2021

Peste des petits ruminants (PPR) or goat plague is considered a leading, highly contagious, and most lethal infectious viral disease of small ruminants affecting the worldwide livestock economy and international animal trade. Although sheep and goats are the primarily affected, the PPR Virus (PPRV) host range has expanded to other livestock (large ruminants) and wildlife animals over the last few decades, resulting in serious concern to the ongoing PPR global eradication program, which is primarily optimized, designed, and targeted towards accessible sheep and goat population. A systematic review and meta-analysis study was conducted to estimate the prevalence and spill-over infection of PPRV in large ruminants (bovine and camel) and wildlife. Published articles from 2001 to October 2021 on the "PPR" were searched in four electronic databases of PubMed, Scopus, Science direct, and Google Scholars. The articles were then selected using inclusion criteria (detection/prevalence of PPRV in bovine, camel, and wildlife population), exclusion criteria (only sheep or goats, lack of prevalence data, experimental trial, test evaluation, and reviews written in other languages or published before 2001), and the prevalence was estimated by random effect meta-analysis model. In the current study, all published articles belonged to Africa and Asia. The overall pooled prevalence of PPR estimates was 24% (95% CI: 15-33), with 30% in Asia (95% CI: 14-49) and 20% in Africa (95% CI: 11-30). The overall estimated pooled prevalence at an Africa-Asia level in bovine and camel was 13% (95% CI: 8-19), and in wildlife, it was 52% (95% CI: 30-74) with significant heterogeneity (I² = 97%) in most pooled estimates with a high prevalence in atypical hosts and wildlife across Asia and Africa. Over the last two decades, the host range has increased drastically in the wildlife population, even for prevalent PPR in the unnatural hosts only for a short time, contributing to virus persistence in multi-host systems with an impact on PPR control and eradication program. This observation on the epidemiology of the PPRV in unnatural hosts demands appropriate intervention strategies, particularly at the livestock-wildlife interface.

Analysis and Sequence Alignment of Peste des Petits Ruminants Virus ChinaSX2020

The peste des petits ruminants virus (PPRV) mainly infects goats and sheep and causes a highly contagious disease, PPR. Recently, a PPRV strain named ChinaSX2020 was isolated and confirmed following an indirect immunofluorescence assay and PCR using PPRV-specific antibody and primers, respectively. A sequencing of the ChinaSX2020 strain showed a genome length of 15,954 nucleotides. A phylogenetic tree analysis showed that the ChinaSX2020 genome was classified into lineage IV of the PRRV genotypes. The genome of the ChinaSX2020 strain was found to be closely related to PPRVs isolated in China between 2013 and 2014. These findings revealed that not a variety of PRRVs but similar PPRVs were continuously spreading and causing sporadic outbreaks in China.

Complete Genome Sequencing of Field Isolates of Peste des Petits Ruminants Virus from Tanzania Revealed a High Nucleotide Identity with Lineage III PPR Viruses

Peste des petits ruminants virus (PPRV) causes a highly devastating disease of sheep and goats that threatens food security, small ruminant production and susceptible endangered wild ruminants. With policy directed towards achieving global PPR eradication, the establishment of cost-effective genomic surveillance tools is critical where PPR is endemic. Genomic data can provide sufficient in-depth information to identify the pockets of endemicity responsible for PPRV persistence and viral evolution, and direct an appropriate vaccination response. Yet, access to the required sequencing technology is low in resource-limited settings and is compounded by the difficulty of transporting clinical samples from wildlife across international borders due to the Convention on International Trade in Endangered Species (CITES) of Wild Fauna and Flora, and Nagoya Protocol regulations. Oxford nanopore MinION sequencing technology has recently demonstrated an extraordinary performance in the sequencing of PPRV due to its rapidity, utility in endemic countries and comparatively low cost per sample when compared to other whole-genome (WGS) sequencing platforms. In the present study, Oxford nanopore MinION sequencing was utilised to generate complete genomes of PPRV isolates collected from infected goats in Ngorongoro and Momba districts in the northern and southern highlands of Tanzania during 2016 and 2018, respectively. The tiling multiplex polymerase chain reaction (PCR) was carried out with twenty-five pairs of long-read primers. The resulting PCR amplicons were used for nanopore library preparation and sequencing. The analysis of output data was complete genomes of PPRV, produced within four hours of sequencing (accession numbers: MW960272 and MZ322753). Phylogenetic analysis of the complete genomes revealed a high nucleotide identity, between 96.19 and 99.24% with lineage III PPRV currently circulating in East Africa, indicating a common origin. The Oxford nanopore MinION sequencer can be deployed to overcome diagnostic and surveillance challenges in the PPR Global Control and Eradication program. However, the coverage depth was uneven across the genome and amplicon dropout was observed mainly in the GC-rich region between the matrix (M) and fusion (F) genes of PPRV. Thus, larger field studies are needed to allow the collection of sufficient data to assess the robustness of nanopore sequencing technology.

A predictive analysis on the risk of peste des petits ruminants in livestock in the Trans-Himalayan region and validation of its transboundary transmission paths

Although the Trans-Himalayan region (THR) is an important endemic and rendezvous area of peste des petits ruminants (PPR), monitoring and prevention measurements are difficult to execute because of the rough geographical conditions. Besides, a heterogeneous breeding system and the poor veterinary service of susceptible animals compound the existing problems. Here, we propose a forecasting system to define the key points of PPR prevention and aid the countries in saving time, labor, and products to achieve the goal of the global eradication project of PPR. The spatial distribution of PPR was predicted in the THR for the first time using a niche model that was constructed with a combination of eco-geographical, anthropoid, meteorological, and host variables. The transboundary least-cost paths (LCPs) of small ruminants in the THR were also calculated. Our results reveal that the low-elevation area of the THR had a higher PPR risk and was mainly dominated by human variables. The high-elevation area had lower risk and was mainly dominated by natural variables. Eight LCPs representing corridors among India, Nepal, Bhutan, Bangladesh, and China were obtained. This confirmed the potential risk of transboundary communication by relying on PPR contamination on the grasslands for the first time. The predicted potential risk communication between the two livestock systems and landscapes (high and low elevation) might play a role in driving PPR transboundary transmission.

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.