Co-circulation of Peste-des-Petits-Ruminants Virus Asian lineage IV with Lineage II in Nigeria

First Report of the Emergence of Peste des Petits Ruminants Lineage IV Virus in Senegal

Peste des petits ruminants (PPR) is a highly contagious viral disease and one of the deadliest affecting wild goats, sheep, and small ruminants; however, goats are generally more sensitive. The causative agent is the Peste des Petits Ruminants virus (PPRV), which is a single-stranded RNA virus of negative polarity belonging to the Paramyxoviridae family. In February 2020, an active outbreak of PPR was reported in a herd of a transhumant farmer in the village of Gainth Pathé (department of Kounguel, Kaffrine region, Senegal). Of the ten swabs collected from the goats, eight returned a positive result through a quantitative real-time PCR. The sample that yielded the strongest signal from the quantitative real-time PCR was further analyzed with a conventional PCR amplification and direct amplicon sequencing. A phylogenetic analysis showed that the sequence of the PPR virus obtained belonged to lineage IV. These results confirm those found in the countries bordering Senegal and reinforce the hypothesis of the importance of animal mobility between these neighboring countries in the control of PPRV. In perspective, following the discovery of this lineage IV in Senegal, a study on its dispersion is underway throughout the national territory. The results that will emerge from this study, associated with detailed data on animal movements and epidemiological data, will provide appropriate and effective information to improve PPR surveillance and control strategies with a view to its eradication.

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.

The Spread of Peste Des Petits Ruminants Virus Lineage IV in West Africa

Monitoring the transboundary spread of peste des petits ruminants (PPR) virus is an essential part of the global efforts towards the eradication of PPR by 2030. There is growing evidence that Lineage IV is becoming the predominant viral lineage, replacing Lineage I and II in West Africa. As part of a regional investigation, samples collected in Burkina Faso, Côte d'Ivoire, Guinea and Ghana were screened for the presence of PPRV. A segment of the nucleoprotein gene from positive samples was sequenced, and phylogenetic analysis revealed the co-circulation of Lineage II and IV in Burkina Faso, Côte d'Ivoire and Guinea, and the identification of Lineage IV in Ghana. These data will be of importance to local and regional authorities involved in the management of PPRV spread.

Simultaneous detection and identification of Peste des petits ruminants Virus Lineages II and IV by MCA-Based real-time quantitative RT-PCR assay within single reaction

BACKGROUND

Peste des petits ruminants (PPR) disease is a cross-species infectious disease that severely affects small ruminants and causes great losses to livestock industries in various countries. Distinguishing vaccine-immunized animals from naturally infected animals is an important prerequisite for the eradication of PPR. At present PPRV are classified into lineages I through IV, and only one vaccination strain, Nigeria/75/1, belongs to lineage II, but all of the epidemic strains in China at present are from lineage IV.

RESULTS

To achieve this goal, we developed an SYBR Green I real-time qRT-PCR method for rapid detection and identification of PPRV lineages II and IV by analyzing different melting curve analyses. The negative amplification of other commonly circulating viruses such as orf virus, goat poxvirus, and foot-and-mouth disease virus demonstrated that primers targeting the L gene of PPRV were extremely specific. The sensitivity of the assay was assessed based on plasmid DNA and the detection limit achieved was 100 copies of PPRV lineages II and IV.

CONCLUSION

Since the method has high sensitivity, specificity, and reproducibility, it will be effectively differentiated PPRV lineages II from PPRV lineages IV in PPRV infected animals.

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.

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.

Prevalence, Risk Factors for Exposure, and Socio-Economic Impact of Peste Des Petits Ruminants in Karenga District, Karamoja Region, Uganda

Peste des petits ruminants (PPR), a disease caused by small ruminant morbillivirus (SRM), is highly contagious with high morbidity and mortality. Controlling PPR requires a proper understanding of the epidemiological dynamics and impact of the disease in a range of geographical areas and management systems. Karenga district, located in the pastoral region of Karamoja in northeastern Uganda, and in the vicinity of Kidepo Valley National Park, is characterised by free cross-border (South Sudan and Kenya) livestock trade, communal grazing, and transhumance. This study was conducted from November through December 2020 to determine the seroprevalence of anti-SRM antibodies, the risk factors associated with the occurrence, and the socio-economic impact of PPR in Karenga. A total of 22 kraals were randomly selected from all administrative units, and 684 small ruminants (sheep = 115, goats = 569) were selected for serum collection using systematic random sampling. Exposure to SRM was determined using a competitive enzyme-linked immunosorbent assay. The overall true seroprevalence of SRM antibodies was high, 51.4 (95% confidence interval [CI] 45–52.6). Multivariate logistic regression for risk factors showed that seroprevalence varied significantly by location (26.8% to 87.8%, odds ratio (OR) ≤ 14.5). The odds of exposure to SRM were higher in sheep (73.9%) than in goats (43.8%) (OR = 1.7, p = 0.08), and seropositivity was higher in animals greater than two years old (65.5%; OR = 11.1, p < 0.001), or those one to two years old (24.7%; OR = 1.6, p = 0.2), compared to small ruminants less than one year old (16.1%). Using participatory epidemiology approaches (semi-structured interviews, clinical examinations, pairwise ranking, proportional piling, impact matrix scoring) with 15 key informants and 22 focus groups of pastoralists, PPR was the second most important small ruminant disease: relative morbidity 14%, relative mortality 9%, and case fatality rate 78%, and impacted productivity mainly in terms of treatment costs, mortality, marketability, and conflicts. These findings provide evidence to support the implementation of disease surveillance and control strategies to mitigate the impact of PPR in Karamoja and other pastoral areas in eastern Africa.

Development and Evaluation of a Nested PCR for Improved Diagnosis and Genetic Analysis of Peste des Petits Ruminants Virus (PPRV) for Future Use in Nascent PPR Eradication Programme

Peste des petits ruminants (PPR) is a highly contagious viral disease of small ruminants caused by PPR virus (PPRV). PPR is endemic in Asia, the Middle East and across large areas of Africa and is currently targeted for global eradication by 2030. The virus exists as four different lineages that are usually limited to specific geographical areas. However, recent reports of spread of PPRV, in particular of lineage IV viruses to infection-free countries and previously PPR endemic areas are noteworthy. A rapid and accurate laboratory diagnosis and reports on its epidemiological linkage for virus spread play a major role in the effective control and eradication of the disease. Currently, molecular assays, including conventional reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR (RT-qPCR) are usually used for diagnosis of PPR while the sequencing of part of the nucleocapsid gene is usually carried out for the viral lineage identification. However, it is difficult to diagnose and sequence the genetic material if the animal excreted a low level of virus at the initial stage of infection or if the PPRV is degraded during the long-distance transportation of samples to the reference laboratories. This study describes the development of a novel nested RT-PCR assay for the detection of the PPRV nucleic acid by targeting the N-protein gene, compares the performance of the assay with the existing conventional RT-PCR and also provides good-quality DNA suitable for sequencing in order to identify circulating lineages. The 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. This assay provides a solution with an easy, accurate, rapid and cost-effective PPR diagnostic and partial genome sequencing for use in resource-limited settings.

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.

Wide circulation of peste des petits ruminants virus in sheep and goats across Nigeria

Peste des petits ruminants (PPR) is a highly contagious viral disease that mainly affects goats and sheep in Asia, Africa and the Middle East, and threatens Europe [R.E.1]. The disease is endemic on the African continent, particularly in West Africa, and is a major factor driving food insecurity in low-income populations. The aim of this research study was to carry out surveillance, genetic characterisation and isolation of recently circulating PPR viruses (PPRV) in sheep and goats from the six agro-ecological zones of Nigeria. A total of 268 post-mortem tissue samples of lung and mesenteric ganglia were collected from clinically suspected sheep and goats in 18 different states, of which five never previously sampled. The presence of PPRV was confirmed using a reverse-transcription coupled with a polymerase chain reaction (RT-PCR) assay. A total of 72 samples, 17 sheep (6%) and 55 goats (21%), were found to be PPR positive. Positive samples were distributed in almost all states, except Kano, where PPR was detected in previous studies. The PPRV-positive samples were further confirmed by sequencing or virus isolation in areas where the infection had never previously been detected. These results confirm the active circulation of PPRV across all six agro-ecological zones of Nigeria, and consequently, the need for introducing strict measures for the control and prevention of the disease in the country.

Molecular epidemiology of peste des petits ruminants virus in Nigeria: An update

Peste des petits ruminants (PPR) is a highly contagious viral disease that mainly affects goats and sheep in Asia, Africa and the Middle East. The PPR virus (PPRV) can be classified into four genetically distinct lineages (I, II, III and IV). All have been historically present in Africa, except the Asian lineage IV that has been spreading across the globe and across Africa in recent decades. Previous studies have identified the presence of lineage IV in Nigeria since 2010. In the present study, samples were taken from 429 small ruminants with PPR symptoms across Nigeria in 2017–2020 to provide an update on the distribution and genetic diversity of PPRV in the country. Sequences from a portion of the PPRV nucleoprotein (N) gene were obtained from 91 samples, 90 belonging to lineage IV and one to lineage II. Phylogenetic analysis identified at least four lineage IV sub‐clusters in Nigeria, grouping samples across multiple regions. Our results suggest extensive endemic circulation of a wide range of PPRV strains across Nigeria and across borders with neighbouring countries, underlining the difficulty involved in controlling the disease in the region.

Persistence of the historical lineage I of West Africa against the ongoing spread of the Asian lineage of peste des petits ruminants virus

Peste des petits ruminants (PPR) is a highly contagious disease of small ruminants. The causal agent, PPR virus (PPRV), is classified into four genetically distinct lineages. Lineage IV, originally from Asia, has shown a unique capacity to spread across Asia, the Middle East and Africa. Recent studies have reported its presence in two West African countries: Nigeria and Niger. Animals are frequently exchanged between Mali and Niger, which could allow the virus to enter and progress in Mali and to other West African countries. Here, PPRV samples were collected from sick goats between 2014 and 2017 in both Mali and in Senegal, on the border with Mali. Partial PPRV nucleoprotein gene was sequenced to identify the genetic lineage of the strains. Our results showed that lineage IV was present in south‐eastern Mali in 2017. This is currently the furthest West the lineage has been detected in West Africa. Surprisingly, we identified the persistence at least until 2014 of the supposedly extinct lineage I in two regions of Mali, Segou and Sikasso. Most PPRV sequences obtained in this study belonged to lineage II, which is dominant in West Africa. Phylogenetic analyses showed a close relationship between sequences obtained at the border between Senegal and Mali, supporting the hypothesis of an important movement of the virus between the two countries. Understanding the movement of animals between these countries, where the livestock trade is not fully controlled, is very important in the design of efficient control strategies to combat this devastating disease.

Peste des petits ruminants in Africa: a review of currently available molecular epidemiological data, 2020

Small ruminants (e.g., sheep and goats) contribute considerably to the cash income and nutrition of small farmers in most countries in Africa and Asia. Their husbandry is threatened by the highly infectious transboundary viral disease peste des petits ruminants (PPR) caused by peste-des-petits-ruminants virus (PPRV). Given its social and economic impact, PPR is presently being targeted by international organizations for global eradication by 2030. Since its first description in Côte d’Ivoire in 1942, and particularly over the last 10 years, a large amount of molecular epidemiological data on the virus have been generated in Africa. This review aims to consolidate these data in order to have a clearer picture of the current PPR situation in Africa, which will, in turn, assist authorities in global eradication attempts.

Prevalence and molecular characterization of some circulating strains of the peste-des-petits-ruminants virus in Saudi Arabia between 2014-2016

Background

The peste-des-petits-ruminants virus (PPRV) is a highly devastating virus of small ruminants in many parts of the world, including the Kingdome of Saudi Arabia. Therefore, our objectives were (1) to conduct a molecular prevalence study of PPRV in sheep and goat across the KSA and (2) to isolate and identify currently circulating PPRV lineages. Swabs and tissue specimens were collected from 97 herds suspected to be infected with PPRV across the Kingdome of Saudi Arabia (KSA). Testing for the presence of the virus was done by the real-time PCR. Confirmation of the identity of the reactions was done by the gel-based-PCR then by sequencing of the partial PPRV genome.

Results

Our results revealed that 24.1% of the tested specimens were PPRV-positive. Isolation of PPRV was successful from samples using the Vero cell line. Sequence analysis of some partial PPRV genes (N, F, M, L, P, and H) revealed that these strains were belonging to lineage IV of the PPRV.

Conclusions

This is the first study to conduct both the nationwide prevalence, isolation, and molecular characterizations of the PPRV in the KSA. Continuous surveillance and monitoring of the circulating strains of PPRV among sheep and goats will contribute substantially to the global eradication campaign of such a virus.

Molecular epidemiology of peste des petits ruminants in Niger: An update

Like many West African countries, outbreaks of peste des petits ruminants (PPR), an economically important disease of goats and sheep, are regularly reported in Niger. The causative virus, peste des petits ruminants virus (PPRV), can be differentiated into four genetically distinct lineages. A publication in 2018 identified three PPRV lineages circulating in the country in 2001 (lineages I and II) and 2013 (lineage IV), respectively. In this present study, more recent samples were collected from goats and sheep in locations throughout Niger between 2011 and 2017. Twelve PPRV-positive samples were characterized by sequencing of a segment of the nucleocapsid protein (N) gene. Phylogenetic analysis of the sequences identified viruses from lineages II and IV only. The analysis also indicated a shared origin of the viruses from Niger with PPRVs from neighbouring countries suggesting transboundary movement.

Peste des petits ruminants viruses of lineages II and III identified in the Democratic Republic of the Congo

Understanding the molecular epidemiology and evolution of peste des petits ruminants virus (PPRV), the causative agent of Peste des petits ruminants, can assist in the control of the transboundary spread of this economically important disease. To date, despite having been reported in the majority of northern and central African countries, no molecular epidemiological data on PPRVs are available for the Democratic Republic of the Congo (DRC). This study reports the collection and analysis of 11 samples collected from three provinces of the DRC in 2016 and 2018. Sequence analysis identified two (i.e. II and III) of the four known lineages of PPRV in the country providing important information that will assist in the global eradication of PPR.

Co-infection of peste des petits ruminants and goatpox in a mixed flock of sheep and goats in Kanam, North Central Nigeria

Peste‐des‐petits‐ruminants (PPR) and Goat pox (GTP) are two devastating and economically important transboundary animal diseases of small ruminants in Africa and Asia that have been difficult to control. This study however, investigated an outbreak of PPR and GTP in a mixed flock of indigenous sheep and goats in Kanam, North Central Nigeria. A total of nine sera and seven tissues (lungs, spleen, scab and skin) samples were collected and analysed in the laboratory using competitive enzyme linked immunosorbent assay (cELISA) for PPR antibodies and polymerase chain reaction (PCR) for detection of PPR virus (PPRV) and GTP virus (GTPV). Gene fragments of the nucleoprotein of PPRV and the G‐protein‐coupled chemokine receptor (GPCR) of GTPV were amplified and sequenced to confirm the presence of the causative viruses. Serologically, antibodies to PPRV were detected in all (9/9) sera collected. GTPV and PPRV was detected in corresponding samples (42.8% n = 3/7) of the scab/skin samples collected by both PCR and RT‐PCR technique. The phylogenetic analysis of PPRV revealed that the virus belongs to lineage IV and clustered with viruses from Gabon and Cameroon. Similarly, the GTPV also clustered with other sequences from Burkina Faso and Yemen. The positive cELISA, RT‐PCR and PCR results from samples collected from the same animals confirmed co‐infection of PPR and GTP in this mixed flock of sheep and goats. This is the first report of concurrent infection of PPR and GTP in mixed flock of sheep and goats in Nigeria. Our findings underscore the need for farmers to vaccinate their flock to control spread and economic losses as result of these diseases.

Peste des petits ruminants in Africa: Meta-analysis of the virus isolation in molecular epidemiology studies

Peste des petits ruminant (PPR) is a highly contagious, infectious viral disease of small ruminant species which is caused by the peste des petits ruminants virus (PPRV), the prototype member of the Morbillivirus genus in the Paramyxoviridae family. Peste des petits ruminant was first described in West Africa, where it has probably been endemic in sheep and goats since the emergence of the rinderpest pandemic and was always misdiagnosed with rinderpest in sheep and goats. Since its discovery PPR has had a major impact on sheep and goat breeders in Africa and has therefore been a key focus of research at the veterinary research institutes and university faculties of veterinary medicine in Africa. Several key discoveries were made at these institutions, including the isolation and propagation of African PPR virus isolates, notable amongst which was the Nigerian PPRV 75/1 that was used in the scientific study to understand the taxonomy, molecular dynamics, lineage differentiation of PPRV and the development of vaccine seeds for immunisation against PPR. African sheep and goat breeds including camels and wild ruminants are frequently infected, manifesting clinical signs of the disease, whereas cattle and pigs are asymptomatic but can seroconvert for PPR. The immunisation of susceptible sheep and goats remains the most effective and practical control measure against PPR. To carry out PPR vaccination in tropical African countries with a very high temperature, a thermostable vaccine using the rinderpest lyophilisation method to the attenuated Nigeria 75/1 PPR vaccine strain has been developed, which will greatly facilitate the delivery of vaccination in the control, prevention and global eradication of PPR. Apart from vaccination, other important questions that will contribute towards the control and prevention of PPR need to be answered, for example, to identify the period when a susceptible naïve animal becomes infectious when in contact with an infected animal and when an infectious animal becomes contagious.

First genetic characterization of Peste des Petits Ruminants from Niger: On the advancing front of the Asian virus lineage

Peste des Petits Ruminants (PPR) is a serious transboundary infectious disease of small ruminants. The causal agent, PPR virus (PPRV), can be separated into four genetically distinct lineages using phylogenetic analysis. In recent decades, lineage IV of PPRV has dramatically extended its geographic distribution from Asia to the Middle East and to Africa, where it has progressively replaced other PPRV lineages. Lineages I and II are historically distributed in West Africa. Currently, lineage II appears to dominate the region, whereas the last recorded occurrence of lineage I dates back to 1994. Recent studies reported the presence of lineage IV in Nigeria, suggesting that this lineage is expanding in West Africa. In Niger, a close neighbour of Nigeria, PPRV has never been genetically characterized, despite reports of PPR incidence. In this study, pathological samples collected from sick goats were collected in 2013 during a suspected PPR outbreak in southern Niger close to the Nigerian border were compared to samples collected in a previous investigation in October 2001 in south-western Niger. These strains were characterized by sequencing and phylogenetic analysis to identify their genetic lineage. Our results show that in 2001, lineages I and II were cocirculating in south-western Niger, whereas the strain that caused the outbreak in 2013 belonged to lineage IV and is closely related to strains identified in Nigeria. These results confirm the progression of lineage IV in West Africa. The process of PPRV lineage replacement and its implications for the epidemiology and the control of the disease in this region are unclear and should be the subject of further studies in the field.

Genome sequencing of an Indian peste des petits ruminants virus isolate, Izatnagar/94, and its implications for virus diversity, divergence and phylogeography

Peste des petits ruminants is an important transboundary disease infecting small ruminants. Genome or gene sequence analysis enriches our knowledge about the evolution and transboundary nature of the causative agent of this disease, peste des petits ruminants virus (PPRV). Although analysis using whole genome sequences of pathogens leads to more precise phylogenetic relationships, when compared to individual genes or partial sequences, there is still a need to identify specific genes/genomic regions that can provide evolutionary assessments consistent with those predicted with full-length genome sequences. Here the virulent Izatnagar/94 PPRV isolate was assembled and compared to all available complete genome sequences (currently in the NCBI database) to estimate nucleotide diversity and to deduce evolutionary relationships between genes/genomic regions and the full length genomes. Our aim was to identify the preferred candidate gene for use as a phylogenetic marker, as well as to predict divergence time and explore PPRV phylogeography. Among all the PPRV genes, the H gene was identified to be the most diverse with the highest evolutionary relationship with the full genome sequences. Hence it is considered as the most preferred candidate gene for phylogenetic study with 93% identity set as a nucleotide cutoff. A whole genome nucleotide sequence cutoff value of 94% permitted specific differentiation of PPRV lineages. All the isolates examined in the study were found to have a most recent common ancestor in the late 19th or in the early 20th century with high posterior probability values. The Bayesian skyline plot revealed a decrease in genetic diversity among lineage IV isolates since the start of the vaccination program and the network analysis localized the ancestry of PPRV to Africa.

Advances in peste des petits ruminants vaccines

Peste des petits ruminants (PPR) is a highly contagious disease of small ruminants that leads to high morbidity and mortality thereby results in devastating economic consequences to the livestock industry. PPR is currently endemic across most parts of Asia and Africa, the two regions with the highest concentration of poor people in the world. Sheep and goats in particularly contribute significantly towards the upliftment of livelihood of the poor and marginal farmers in these regions. In this context, PPR directly affecting the viability of sheep and goat husbandry has emerged as a major hurdle in the development of these regions. The control of PPR in these regions could significantly contribute to poverty alleviation, therefore, the Office International des Epizooties (OIE) and Food and Agricultural Organization (FAO) have targeted the control and eradication of PPR by 2030 a priority. In order to achieve this goal, a potent, safe and efficacious live-attenuated PPR vaccine with long-lasting immunity is available for immunoprophylaxis. However, the live-attenuated PPR vaccine is thermolabile and needs maintenance of an effective cold chain to deliver into the field. In addition, the infected animals cannot be differentiated from vaccinated animals. To overcome these limitations, some recombinant vaccines have been developed. This review comprehensively describes about the latest developments in PPR vaccines.

Comparison of nucleotide sequences of recent and previous lineages of peste-des-petits-ruminants viruses of sheep and goats in Nigeria

Peste-des-petits-ruminants virus (PPRV) is a highly contagious, fatal and economically important viral disease of small ruminants that is still endemic and militates against the production of sheep and goats in endemic areas of the world. The aim of this study was to describe the viral strains within the country. This was carried out by collecting tissue and swab samples from sheep and goats in various agro-ecological zones of Nigeria. The phylogeny of archived PPRV strains or isolates and those circulating and causing recent outbreaks was determined by sequencing of the nucleoprotein (N)-gene. Twenty tissue and swab samples from apparently healthy and sick sheep and goats were collected randomly from 18 states, namely 3 states in each of the 6 agro-ecological zones visited. A total of 360 samples were collected. A total of 35 samples of 360 (9.7%) tested positive by reverse transcriptase–polymerase chain reaction, of which 25 were from oculo-nasal swabs and 10 were from tissue samples. Neighbour-joining phylogenetic analysis using Phylogenetic Analysis Using Parsimony (PAUP) identified four different lineages, that is, lineages I, II, III and IV. Interestingly, the Nigerian strains described in this study grouped in two separate major lineages, that is, lineages II and IV. Strains from Sokoto, Oyo, Plateau and Ondo states grouped according to the historical distribution of PPRV together with the Nigerian 75/1 strain of lineage II, while other strains from Sokoto, Oyo, Plateau, Akwa-Ibom, Adamawa, Kaduna, Lagos, Bauchi, Niger and Kano states grouped together with the East African and Asian strains of lineage IV. This finding confirms that both lineage II and IV strains of PPRV are circulating in Nigeria. Previously, only strains of lineage II were found to be present in the country.