Optimization and evaluation of a non-invasive tool for peste des petits ruminants surveillance and control

The Live Attenuated Vaccine Strain "ARRIAH" Completely Protects Goats from a Virulent Lineage IV Field Strain of Peste Des Petits Ruminants Virus

Peste des petits ruminants (PPR) is a transboundary viral disease that affects small ruminants, such as goats and sheep, in Africa, the Middle East, and Asia, causing substantial damage to livelihoods and disrupting livestock trade. Although Russia is PPR virus (PPRV)-free, controlling PPRV in neighboring countries is the top national priority. Recent PPR outbreaks in Mongolia and other countries in the Middle East caused by a lineage IV virus represent a risk of transboundary emergence in neighboring countries, including China, Kazakhstan, and Russia. In the present study, we assessed the potency and safety of the ARRIAH live attenuated PPRV vaccine (lineage II) in Zaannen and Nubian goat breeds by challenging them with a virulent lineage IV Mongolia/2021 isolate. For comparison, two commercial vaccines of Nigeria75/1 strain were used. The ARRIAH-vaccinated animals showed an increase in body temperature of 1-1.5 °C above the physiological norm, similar to the animals vaccinated with Nigeria75/1 vaccines. In all vaccinated groups, the average rectal temperature never exceeded 39.4-39.7 °C throughout the infection period, and no clinical signs of the disease were observed, demonstrating vaccine efficacy and safety in the current experimental setting. However, the control group (mock vaccinated) challenged with Mongolia/2021 PPRV exhibited moderate-to-severe clinical signs. Overall, the findings of the present study demonstrate that the ARRIAH vaccine strain has a promising protective phenotype compared with Nigeria75/1 vaccines, suggesting its potential as an effective alternative for curbing and controlling PPR in affected countries. Although the ARRIAH vaccine against PPR is not currently endorsed by the World Organization for Animal Health due to its incomplete safety and potency profile, this study is the first step to provide experimentally validated data on the ARRIAH vaccine.

Metagenomic and Molecular Detection of Novel Fecal Viruses in Free-Ranging Agile Wallabies

The agile wallaby (Notamacropus agilis) is one of the most abundant marsupial species in northern Queensland and a competent host for the zoonotic Ross River virus. Despite their increased proximity and interactions with humans, little is known about the viruses carried by these animals, and whether any are of conservation or zoonotic importance. Metagenomics and molecular techniques were used in a complementary manner to identify and characterize novel viruses in the fecal samples of free-ranging agile wallabies. We detected a variety of novel marsupial-related viral species including agile wallaby atadenovirus 1, agile wallaby chaphamaparvovirus 1-2, agile wallaby polyomavirus 1-2, agile wallaby associated picobirnavirus 1-9, and a known macropod gammaherpesvirus 3. Phylogenetic analyses indicate that most of these novel viruses would have co-evolved with their hosts (agile wallabies). Additionally, non-marsupial viruses that infect bacteria (phages), plants, insects, and other eukaryotes were identified. This study highlighted the utility of non-invasive sampling as well as the integration of broad-based molecular assays (consensus PCR and next generation sequencing) for monitoring the emergence of potential pathogenic viruses in wildlife species. Furthermore, the novel marsupial viruses identified in this study will enrich the diversity of knowledge about marsupial viruses, and may be useful for developing diagnostics and vaccines.

Microparticles as Viral RNA Carriers from Stool for Stable and Sensitive Surveillance

Since its discovery, polymerase chain reaction (PCR) has emerged as an important technology for the diagnosis and identification of infectious diseases. It is a highly sensitive and reliable nucleic acids (NA) detection tool for various sample types. However, stool, which carries the most abundant micro-organisms and physiological byproducts, remains to be the trickiest clinical specimen for molecular detection of pathogens. Herein, we demonstrate the novel application of hydrogel microparticles as carriers of viral RNA from stool samples without prior RNA purification for real-time polymerase chain reaction (qPCR). In each microparticle of primer-incorporated network (PIN) as a self-sufficient reaction compartment, immobilized reverse transcription (RT) primers capture the viral RNA by hybridization and directly initiate RT of RNA to generate a pool of complementary DNA (PIN-cDNA pool). Through a simple operation with a portable thermostat device, a PIN-cDNA pool for influenza A virus (IAV) was obtained in 20 min. The PIN-cDNA pools can be stored at room temperature, or directly used to deliver cDNA templates for qPCR. The viral cDNA templates were freely released in the subsequent qPCR to allow amplification efficiency of over 91%. The assay displayed good linearity, repeatability, and comparable limit of detection (LoD) with a commercialized viral RNA purification kit. As a proof of concept, this technology carries a huge potential for onsite application to improve human and animal infectious disease surveillance activities using stool samples without the need for a laboratory or centrifuge for sample preparation.

The Experimental Infection of Goats with Small Ruminant Morbillivirus Originated from Barbary Sheep

Peste des Petits Ruminants (PPR) is a transboundary contagious disease in domestic small ruminants. Infections with the small ruminant morbillivirus (SRMV) were regularly found in wildlife, with unknown roles in PPR epidemiology. In order to access infection dynamics and virulence, we infected German Edelziege goats intranasally with a SRMV isolate that originated from Barbary sheep from an outbreak in the United Arab Emirates. Six goats were infected with cell culture-isolated SRMV, and two goats were kept in contact. Goats were daily monitored, and clinical score was recorded. EDTA blood, nasal, conjunctival and rectal swab samples were collected for the detection of SRMV genome load and serum for serological analysis. Short incubation period in infected (4 to 5 dpi) as well as in contact goats (9 dpi) was followed by typical clinical signs related to PPR. The highest viral load was detectable in conjunctival and nasal swab samples with RT-qPCR and rapid pen-side test. Specific antibodies were detected at 7 dpi in infected and 14 dpi in contact goats. In general, high virulence and easy transmission of the virus originated from wildlife in domestic goats was observed. The virus isolate belongs to Asian lineage IV, genetically related to Chinese and Mongolian strains.

Epidemiology of Peste des Petits Ruminants in Nigeria: A Review

Peste des petits ruminants (PPR) is a major constraint to the productivity of small ruminants in Nigeria. Understanding of the current epidemiological status of PPR is crucial to its effective control. A review of the epidemiology of PPR in Nigeria was performed and research gaps were identified. Thirty-seven eligible articles were reviewed: these presented information from 30 of the 36 states of Nigeria. Most studies focused on goats and/or sheep (n = 33) but camels (n = 4), cattle (n = 1) and wild ruminants (n = 2) were also considered. Fourteen (37.8%) of the articles reported seroprevalence in small ruminants, which varied from 0.0% to 77.5% where more than 10 animals were sampled. Molecular characterization and phylogenetic analysis were performed in 6 studies, with lineages II and IV, detected in sheep and goats. In one study in small ruminants, sequences clustering into lineage I showed a similarity to the vaccine strain, Nigeria 75/1, based on phylogenetic analysis of F gene sequences. However, if the preferred method of sequencing the N gene had been performed, this isolate would have been grouped into lineage II. According to N gene phylogenetic analysis in the other studies, sequences were identified that clustered with clade II-NigA, II-NigB (closely related to the Nigeria 75/1 vaccine strain), and others which were well separated, suggesting a high diversity of PPRV in Nigeria. Five articles reported the detection of lineage IV in 22/36 states, with IV-NigA and IV-NigB detected, highlighting its widespread distribution in Nigeria. Risk factors for PPRV seropositivity were reported in 10/37 (27.0%) articles, with a higher seroprevalence observed in female animals, although differing results were observed when considering species and age separately. There were inconsistencies in study design and data reporting between studies which precluded conduct of a meta-analysis. Nevertheless, several research gaps were identified including the need to investigate the low uptake of PPRV vaccine, and the economic benefits of PPR control measures to small ruminant farmers. Such data will inform PPR control strategies in Nigeria and subsequently contribute to the global 2030 PPR eradication strategy.

A Review of Non-Invasive Sampling in Wildlife Disease and Health Research: What's New?

In the last decades, wildlife diseases and the health status of animal populations have gained increasing attention from the scientific community as part of a One Health framework. Furthermore, the need for non-invasive sampling methods with a minimal impact on wildlife has become paramount in complying with modern ethical standards and regulations, and to collect high-quality and unbiased data. We analysed the publication trends on non-invasive sampling in wildlife health and disease research and offer a comprehensive review on the different samples that can be collected non-invasively. We retrieved 272 articles spanning from 1998 to 2021, with a rapid increase in number from 2010. Thirty-nine percent of the papers were focussed on diseases, 58% on other health-related topics, and 3% on both. Stress and other physiological parameters were the most addressed research topics, followed by viruses, helminths, and bacterial infections. Terrestrial mammals accounted for 75% of all publications, and faeces were the most widely used sample. Our review of the sampling materials and collection methods highlights that, although the use of some types of samples for specific applications is now consolidated, others are perhaps still underutilised and new technologies may offer future opportunities for an even wider use of non-invasively collected samples.

Point of care diagnostics and non-invasive sampling strategy: a review on major advances in veterinary diagnostics

The use of point of care diagnostics (POCD) in animal diseases has steadily increased over the years since its introduction. Its potential application to diagnose infectious diseases in remote and resource limited settings have made it an ideal diagnostic in animal disease diagnosis and surveillance. The rapid increase in incidence of emerging infectious diseases requires urgent attention where POCD could be indispensable tools for immediate detection and early warning of a potential pathogen. The advantages of being rapid, easily affordable and the ability to diagnose an infectious disease on spot has driven an intense effort to refine and build on the existing technologies to generate advanced POCD with incremental improvements in analytical performance to diagnose a broad spectrum of animal diseases. The rural communities in developing countries are invariably affected by the burden of infectious animal diseases due to limited access to diagnostics and animal health personnel. Besides, the alarming trend of emerging and transboundary diseases with pathogen spill-overs at livestock-wildlife interfaces has been identified as a threat to the domestic population and wildlife conservation. Under such circumstances, POCD coupled with non-invasive sampling techniques could be successfully deployed at field level without the use of sophisticated laboratory infrastructures. This review illustrates the current and prospective POCD for existing and emerging animal diseases, the status of non-invasive sampling strategies for animal diseases, and the tremendous potential of POCD to uplift the status of global animal health care.

Nucleotide amplification and sequencing of the GC-rich region between matrix and fusion protein genes of peste des petits ruminants virus

Peste des petits ruminants virus (PPRV) causes a highly devastating disease of sheep and goats, that threatens the conservation of small wild ruminants. The development of PPRV vaccines, diagnostics and therapeutics, greatly depends on in-depth genomic data. Yet, high guanine-cytosine (GC) content between matrix (M) and fusion (F) genes of PPRV poses difficulty for both primer design and nucleotide amplification. In turn, this has led into absence or low nucleotide sequence coverage in this region. This poses a risk of missing important part of the genome that could help to infer viral evolution. Here, an overlapping long-read primer-based amplification strategy was developed to amplify the GC-rich fragments between M-F gene junction using nexus gradient polymerase chain reaction (PCR). The resulting amplicons were sequenced by dideoxynucleotide cycle sequencing and compared with other PPRV nucleotide sequences available at GenBank. Our findings indicate clear PCR amplification products with expected size of the GC-rich fragments on agarose gel electrophoresis. The sequencing results of these fragments indicate 99.5 % nucleotide identity with PPRV strain KY628761. An extremely difficult PCR target of 67.4 % GC contents was successfully amplified and sequenced using this long-read primer approach. The long-read primer set may be used in tiling multiplex PCR for complete genome sequencing of PPRV.

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.

Virus distribution and early pathogenesis of highly pathogenic peste-des-petits-ruminants virus in experimentally infected goats

INTRODUCTION

Despite causing one of the most dreaded diseases of small ruminants, relatively little is known about the pathogenic events, antigen distribution and the cells responsible for the uptake and transmission of peste-des-petits-ruminants virus (PPRV) during primitive stages of infection.

OBJECTIVES

We aimed at deciphering the sequential tissue tropism, pathological events and putative role of M2c macrophages during incubatory, prodromal and invasive stages of PPRV infection.

METHODOLOGY

A total of 10 goats were sequentially sacrificed at 1, 2, 3, 4, and 5 days post-infection (dpi, n = 2 per time-point) following intranasal inoculation with a highly virulent strain of PPRV (lineage IV PPRV/Izatnagar/94). Histological evaluation to assess PPRV mediated pathologies, RT-qPCR and immunohistochemistry (IHC) to decipher sequential virus distribution, and dual immunolabelling to determine the role of M2c macrophage in early PPRV uptake and transmission was performed.

RESULTS

PPRV/Izatnagar/94 caused major pathologies in the lung tissues. Unprecedentedly, PPRV nucleic acid and antigens were detected in various tissues as early as one dpi. RT-qPCR revealed PPRV in the nasal cavity, trachea, bronchi, tongue and lymph nodes draining these tissues from 1 dpi. IHC affirms cells residing in the lamina propria and submucosa of the respiratory tract and tongue and peribronchiolar areas of lungs as the primary target of PPRV. Following initial replication in the respiratory tract, PPRV is transmitted to the regional lymph nodes where primary viral amplification occurs. After viraemia and secondary replication in generalized lymphoid tissues, PPRV infects and replicates in the epithelial cells. Further, we localized CD163⁺ M2c macrophages in the goat tissues, but dual IHC elucidated that M2c macrophages do not facilitate uptake and transmission of PPRV during the early stages of infection.

CONCLUSION

Our study substantiates the disease establishment process and pathogenesis of PPRV/Izatnagar/94 during the incubatory and prodromal stages of infection. Further, we have also observed M2c macrophage distribution in the goat tissues and demonstrated that they do not pick and transmit PPRV.

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

Peste des petits ruminants (PPR) is a viral disease of goats and sheep that occurs in Africa, the Middle East and Asia with a severe impact on livelihoods and livestock trade. Many wild artiodactyls are susceptible to PPR virus (PPRV) infection, and some outbreaks have threatened endangered wild populations. The role of wild species in PPRV epidemiology is unclear, which is a knowledge gap for the Global Strategy for the Control and Eradication of PPR. These studies aimed to investigate PPRV infection in wild artiodactyls in the Greater Serengeti and Amboseli ecosystems of Kenya and Tanzania. Out of 132 animals purposively sampled in 2015–2016, 19.7% were PPRV seropositive by ID Screen PPR competition enzyme-linked immunosorbent assay (cELISA; IDvet, France) from the following species: African buffalo, wildebeest, topi, kongoni, Grant’s gazelle, impala, Thomson’s gazelle, warthog and gerenuk, while waterbuck and lesser kudu were seronegative. In 2018–2019, a cross-sectional survey of randomly selected African buffalo and Grant’s gazelle herds was conducted. The weighted estimate of PPRV seroprevalence was 12.0% out of 191 African buffalo and 1.1% out of 139 Grant’s gazelles. All ocular and nasal swabs and faeces were negative by PPRV real-time reverse transcription-polymerase chain reaction (RT-qPCR). Investigations of a PPR-like disease in sheep and goats confirmed PPRV circulation in the area by rapid detection test and/or RT-qPCR. These results demonstrated serological evidence of PPRV infection in wild artiodactyl species at the wildlife–livestock interface in this ecosystem where PPRV is endemic in domestic small ruminants. Exposure to PPRV could be via spillover from infected small ruminants or from transmission between wild animals, while the relatively low seroprevalence suggests that sustained transmission is unlikely. Further studies of other major wild artiodactyls in this ecosystem are required, such as impala, Thomson’s gazelle and wildebeest.

A Review of the Current Status of Peste des Petits Ruminants Epidemiology in Small Ruminants in Tanzania

Peste des petits ruminants (PPR) is a highly contagious viral disease of sheep and goats with high mortality. The disease is of considerable economic importance in countries such as Tanzania, where small ruminant products are important for sustainable livelihoods. This review assesses current knowledge regarding the epidemiology of PPRV in Tanzania, highlighting the challenges with respect to control and suggesting possible interventions. Thirty-three articles were identified after literature searches using Google Scholar and PubMed. Studies revealed that PPRV is endemic in sheep and goats in Tanzania, although seropositivity has also been reported in cattle, camels, buffalo, Grant's gazelle, wildebeest and impala, but with no clinical manifestation. Three lineages (lineage II to IV) of PPRV have been identified in Tanzania, implying at least two separate introductions of the virus. Diagnosis of PPR in Tanzania is mostly by observation of clinical signs and lesions at post mortem. Risk factors in Tanzania include age, sex, species, and close contact of animals from different farms/localities. Although there is an efficacious vaccine available for PPR, poor disease surveillance, low vaccine coverage, and uncontrolled animal movements have been the bane of control efforts for PPR in Tanzania. There is need for collaborative efforts to develop interventions to control and eradicate the disease. The establishment of a national reference laboratory for PPR, conduct of surveillance, the development of high-quality DIVA vaccines, as well as execution of a carefully planned national vaccination campaign may be key to the control and subsequent eradication of PPR in Tanzania and achieving the global goal of eradicating PPR by 2030.

A systemic approach to assess the potential and risks of wildlife culling for infectious disease control

The maintenance of infectious diseases requires a sufficient number of susceptible hosts. Host culling is a potential control strategy for animal diseases. However, the reduction in biodiversity and increasing public concerns regarding the involved ethical issues have progressively challenged the use of wildlife culling. Here, we assess the potential of wildlife culling as an epidemiologically sound management tool, by examining the host ecology, pathogen characteristics, eco-sociological contexts, and field work constraints. We also discuss alternative solutions and make recommendations for the appropriate implementation of culling for disease control.

Comparative evaluation of different antigen detection methods for the detection of peste des petits ruminants virus

Peste des petits ruminants (PPR) is a fatal disease of small ruminants which has spread rapidly to previously PPR-free countries in recent decades, causing enormous economic losses in the affected regions. Here, two newly emerged PPR virus (PPRV) isolates from India and from the Middle East were tested in an animal trial to analyse their pathogenesis, and to evaluate serological and molecular detection methods. Animals infected with the two different PPRV isolates showed marked differences in clinical manifestation and scoring. The PPRV isolate from India was less virulent than the virus from the Middle East. Commercially available rapid detection methods for PPRV antigen (two Lateral Flow Devices (LFDs) and one antigen ELISA) were evaluated in comparison with a nucleic acid detection method. For this purpose, ocular and nasal swabs were used. Due to the easy non-invasive sampling, faecal samples were also analysed. For all rapid antigen detection methods, a high specificity of 100% was observed independent of the sample matrix and dilution buffers used. Both antigen ELISA and LFD tests showed highest sensitivities for nasal swabs. Here, the detection rate of the antigen ELISA, the LFD-PESTE-TEST and the LFD-ID Rapid-Test was 78%, 75% and 78%, respectively. Ocular swabs were less suitable for antigen detection of PPRV. These results reflect the increased viral load in nasal swabs of PPRV infected goats compared to ocular swabs. The faecal samples were the least suitable for antigen detection. In conclusion, nasal swab samples are the first choice for the antigen and genome detection of PPRV. Nevertheless, based on the excellent diagnostic specificity of the rapid tests, positive results generated with other sample matrices are solid. In contrast, negative test results can be caused on the reduced analytical sensitivity of the rapid antigen tests and must be treated with caution.

Characterisation of Peste Des Petits Ruminants Disease in Pastoralist Flocks in Ngorongoro District of Northern Tanzania and Bluetongue Virus Co-Infection

Peste des petits ruminants (PPR) disease was first confirmed in Tanzania in 2008 in sheep and goats in Ngorongoro District, northern Tanzania, and is now endemic in this area. This study aimed to characterise PPR disease in pastoralist small ruminant flocks in Ngorongoro District. During June 2015, 33 PPR-like disease reports were investigated in different parts of the district, using semi-structured interviews, clinical examinations, PPR virus rapid detection test (PPRV-RDT), and laboratory analysis. Ten flocks were confirmed as PPRV infected by PPRV-RDT and/or real-time reverse transcription-polymerase chain reaction (RT-qPCR), and two flocks were co-infected with bluetongue virus (BTV), confirmed by RT-qPCR. Phylogenetic analysis of six partial N gene sequences showed that the PPR viruses clustered with recent lineage III Tanzanian viruses, and grouped with Ugandan, Kenyan and Democratic Republic of Congo isolates. No PPR-like disease was reported in wildlife. There was considerable variation in clinical syndromes between flocks: some showed a full range of PPR signs, while others were predominantly respiratory, diarrhoea, or oro-nasal syndromes, which were associated with different local disease names (olodua-a term for rinderpest, olkipiei-lung disease, oloirobi-fever, enkorotik-diarrhoea). BTV co-infection was associated with severe oro-nasal lesions. This clinical variability makes the field diagnosis of PPR challenging, highlighting the importance of access to pen-side antigen tests and multiplex assays to support improved surveillance and targeting of control activities for PPR eradication.

Eradication of Peste des Petits Ruminants Virus and the Wildlife-Livestock Interface

Growing evidence suggests that multiple wildlife species can be infected with peste des petits ruminants virus (PPRV), with important consequences for the potential maintenance of PPRV in communities of susceptible hosts, and the threat that PPRV may pose to the conservation of wildlife populations and resilience of ecosystems. Significant knowledge gaps in the epidemiology of PPRV across the ruminant community (wildlife and domestic), and the understanding of infection in wildlife and other atypical host species groups (e.g., camelidae, suidae, and bovinae) hinder our ability to apply necessary integrated disease control and management interventions at the wildlife-livestock interface. Similarly, knowledge gaps limit the inclusion of wildlife in the FAO/OIE Global Strategy for the Control and Eradication of PPR, and the framework of activities in the PPR Global Eradication Programme that lays the foundation for eradicating PPR through national and regional efforts. This article reports on the first international meeting on, "Controlling PPR at the livestock-wildlife interface," held in Rome, Italy, March 27-29, 2019. A large group representing national and international institutions discussed recent advances in our understanding of PPRV in wildlife, identified knowledge gaps and research priorities, and formulated recommendations. The need for a better understanding of PPRV epidemiology at the wildlife-livestock interface to support the integration of wildlife into PPR eradication efforts was highlighted by meeting participants along with the reminder that PPR eradication and wildlife conservation need not be viewed as competing priorities, but instead constitute two requisites of healthy socio-ecological systems.

Camelids and Cattle Are Dead-End Hosts for Peste-des-Petits-Ruminants Virus

Peste-des-petits-ruminants virus (PPRV) causes a severe respiratory disease in small ruminants. The possible impact of different atypical host species in the spread and planed worldwide eradication of PPRV remains to be clarified. Recent transmission trials with the virulent PPRV lineage IV (LIV)-strain Kurdistan/2011 revealed that pigs and wild boar are possible sources of PPRV-infection. We therefore investigated the role of cattle, llamas, alpacas, and dromedary camels in transmission trials using the Kurdistan/2011 strain for intranasal infection and integrated a literature review for a proper evaluation of their host traits and role in PPRV-transmission. Cattle and camelids developed no clinical signs, no viremia, shed no or only low PPRV-RNA loads in swab samples and did not transmit any PPRV to the contact animals. The distribution of PPRV-RNA or antigen in lymphoid organs was similar in cattle and camelids although generally lower compared to suids and small ruminants. In the typical small ruminant hosts, the tissue tropism, pathogenesis and disease expression after PPRV-infection is associated with infection of immune and epithelial cells via SLAM and nectin-4 receptors, respectively. We therefore suggest a different pathogenesis in cattle and camelids and both as dead-end hosts for PPRV.

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.

Rapid Detection of Peste des Petits Ruminants Virus (PPRV) Nucleic Acid Using a Novel Low-Cost Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) Assay for Future Use in Nascent PPR Eradication Programme

Peste des petits ruminants (PPR) is a disease of small ruminants caused by peste des petits ruminants virus (PPRV), and is endemic in Asia, the Middle East and Africa. Effective control combines the application of early warning systems, accurate laboratory diagnosis and reporting, animal movement restrictions, suitable vaccination and surveillance programs, and the coordination of all these measures by efficient veterinary services. Molecular assays, including conventional reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR (RT-qPCR) have improved the sensitivity and rapidity of diagnosing PPR. However, currently these assays are only performed within laboratory settings; therefore, the development of field diagnostics for PPR would improve the fast implementation of control policies, particularly when PPR has been targeted to be eradicated by 2030. Loop-mediated isothermal amplification (LAMP) assays are simple to use, rapid, and have sensitivity and specificity within the range of RT-qPCR; and can be performed in the field using disposable consumables and portable equipment. This study describes the development of a novel RT-LAMP assay for the detection of PPRV nucleic acid by targeting the N-protein gene. The RT-LAMP assay was evaluated using cell culture propagated PPRVs, field samples from clinically infected animals and samples from experimentally infected animals encompassing all four lineages (I-IV) of PPRV. The test displayed 100% concordance with RT-qPCR when considering an RT-qPCR cut-off value of C_T >40. Further, the RT-LAMP assay was evaluated using experimental and outbreak samples without prior RNA extraction making it more time and cost-effective. This assay provides a solution for a pen-side, rapid and inexpensive PPR diagnostic for use in the field in nascent PPR eradication programme.