Full genome sequences of two virulent strains of peste-des-petits ruminants virus, the Côte d'Ivoire 1989 and Nigeria 1976 strains

Plasminogen activator urokinase interacts with the fusion protein and antagonizes the growth of Peste des petits ruminants virus

Peste des petits ruminants is an acute and highly contagious disease caused by the Peste des petits ruminants virus (PPRV). Host proteins play a crucial role in viral replication. However, the effect of fusion (F) protein-interacting partners on PPRV infection is poorly understood. In this study, we found that the expression of goat plasminogen activator urokinase (PLAU) gradually decreased in a time- and dose-dependent manner in PPRV-infected goat alveolar macrophages (GAMs). Goat PLAU was subsequently identified using co-immunoprecipitation and confocal microscopy as an F protein binding partner. The overexpression of goat PLAU inhibited PPRV growth and replication, whereas silencing goat PLAU promoted viral growth and replication. Additionally, we confirmed that goat PLAU interacted with a virus-induced signaling adapter (VISA) to antagonize F-mediated VISA degradation, increasing the production of type I interferon. We also found that goat PLAU reduced the inhibition of PPRV replication in VISA-knockdown GAMs. Our results show that the host protein PLAU inhibits the growth and replication of PPRV by VISA-triggering RIG-I-like receptors and provides insight into the host protein that antagonizes PPRV immunosuppression.IMPORTANCEThe role of host proteins that interact with Peste des petits ruminants virus (PPRV) fusion (F) protein in PPRV replication is poorly understood. This study confirmed that goat plasminogen activator urokinase (PLAU) interacts with the PPRV F protein. We further discovered that goat PLAU inhibited PPRV replication by enhancing virus-induced signaling adapter (VISA) expression and reducing the ability of the F protein to degrade VISA. These findings offer insights into host resistance to viral invasion and suggest new strategies and directions for developing PPR vaccines.

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.

PPRV-Induced Autophagy Facilitates Infectious Virus Transmission by the Exosomal Pathway

Peste des petits ruminants virus (PPRV) is an important pathogen that seriously influences the productivity of small ruminants worldwide. We showed previously that PPRV induced sustained autophagy for their replication in host cells. Many studies have shown that exosomes released from virus-infected cells contain a variety of viral and host cellular factors that are able to modulate the recipient's cellular response and result in productive infection of the recipient host. Here, we show that PPRV infection results in packaging of the viral genomic RNA and partial viral proteins into exosomes of Vero cells and upregulates exosome secretion. We provide evidence showing that the exosomal viral cargo can be transferred to and establish productive infection in a new target cell. Importantly, our study reveals that PPRV-induced autophagy enhances exosome secretion and exosome-mediated virus transmission. Additionally, our data show that TSG101 may be involved in the sorting of the infectious PPRV RNA into exosomes to facilitate the release of PPRV through the exosomal pathway. Taken together, our results suggest a novel mechanism involving autophagy and exosome-mediated PPRV intercellular transmission. IMPORTANCE Autophagy plays an important role in PPRV pathogenesis. The role of exosomes in viral infections is beginning to be appreciated. The present study examined the role of autophagy in secretion of infectious PPRV from Vero cells. Our data provided the first direct evidence that ATG7-mediated autophagy enhances exosome secretion and exosome-mediated PPRV transmission. TSG101 may be involved in the sorting of the infectious PPRV RNA genomes into exosomes to facilitate the release of PPRV through the exosomal pathway. Inhibition of PPRV-induced autophagy or TSG101 expression could be used as a strategy to block exosome-mediated virus transmission.

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.

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.

A Novel Recombinant Newcastle Disease Virus Vectored DIVA Vaccine against Peste des Petits Ruminants in Goats

Peste des petits ruminants virus (PPRV, species: small ruminant morbillivirus) is the causative agent of the eponymous notifiable disease, the peste des petits ruminants (PPR) in wild and domestic sheep and goats. Mortality rates vary between 50% and 100%, causing significant losses of estimated 1.5 to 2 billion US Dollars per year. Live-attenuated PPRV vaccine strains are used in the field for disease prevention, but the application of a more thermostable vaccine enabling differentiation between infected and vaccinated animals (DIVA) would be highly desirable to achieve the goal of global disease eradication. We generated a recombinant Newcastle disease virus (rNDV) based on the live-attenuated NDV Clone 30 that expresses the surface protein hemagglutinin (H) of PPRV strain Kurdistan/11 (rNDV_H_Kur). In vitro analyses confirmed transgene expression as well as virus replication in avian, caprine, and ovine cells. Two consecutive subcutaneous vaccinations of German domestic goats with rNDV_H_Kur prevented clinical signs and hematogenic dissemination after an intranasal challenge with virulent PPRV Kurdistan/11. Virus shedding by different routes was reduced to a similar extent as after vaccination with the live-attenuated PPRV strain Nigeria 75/1. Goats that were either not vaccinated or inoculated with parental rNDV were used as controls. In summary, we demonstrate in a proof-of-concept study that an NDV vectored vaccine can protect against PPR. Furthermore, it provides DIVA-applicability and a high thermal tolerance.

Animal morbilliviruses and their cross-species transmission potential

Like measles virus (MV), whose primary hosts are humans, non-human animal morbilliviruses use SLAM (signaling lymphocytic activation molecule) and PVRL4 (nectin-4) expressed on immune and epithelial cells, respectively, as receptors. PVRL4's amino acid sequence is highly conserved across species, while that of SLAM varies significantly. However, non-host animal SLAMs often function as receptors for different morbilliviruses. Uniquely, human SLAM is somewhat specific for MV, but canine distemper virus, which shows the widest host range among morbilliviruses, readily gains the ability to use human SLAM. The host range for morbilliviruses is also modulated by their ability to counteract the host's innate immunity, but the risk of cross-species transmission of non-human animal morbilliviruses to humans could occur if MV is successfully eradicated.

A comprehensive global perspective on phylogenomics and evolutionary dynamics of Small ruminant morbillivirus

A string of complete genome sequences of Small ruminant morbillivirus (SRMV) have been reported from different parts of the globe including Asia, Africa and the Middle East. Despite individual genome sequence-based analysis, there is a paucity of comparative genomic and evolutionary analysis to provide overarching and comprehensive evolutionary insights. Therefore, we first enriched the existing database of complete genome sequences of SRMVs with Pakistan-originated strains and then explored overall nucleotide diversity, genomic and residue characteristics, and deduced an evolutionary relationship among strains representing a diverse geographical region worldwide. The average number of pairwise nucleotide differences among the whole genomes was found to be 788.690 with a diversity in nucleotide sequences (0.04889 ± S.D. 0.00468) and haplotype variance (0.00001). The RNA-dependent-RNA polymerase (L) gene revealed phylogenetic relationship among SRMVs in a pattern similar to those of complete genome and the nucleoprotein (N) gene. Therefore, we propose another useful molecular marker that may be employed for future epidemiological investigations. Based on evolutionary analysis, the mean evolution rate for the complete genome, N, P, M, F, H and L genes of SRMV was estimated to be 9.953 × 10^–4, 1.1 × 10^–3, 1.23 × 10^–3, 2.56 × 10^–3, 2.01 × 10^–3, 1.47 × 10^–3 and 9.75 × 10^–4 substitutions per site per year, respectively. A recombinant event was observed in a Pakistan-originated strain (KY967608) revealing Indian strains as major (98.1%, KR140086) and minor parents (99.8%, KT860064). Taken together, outcomes of the study augment our knowledge and current understanding towards ongoing phylogenomic and evolutionary dynamics for better comprehensions of SRMVs and effective disease control interventions.

Productive replication of peste des petits ruminants virus Nigeria 75/1 vaccine strain in vero cells correlates with inefficiency of maturation of the viral fusion protein

Peste des petits ruminants virus (PPRV), a member of the genus Morbillivirus, in the family Paramyxoviridae expresses two membrane glycoproteins, the fusion (F) and haemagglutinin (H) glycoproteins which mediate virus-to-cell fusion and cell-to-cell fusion leading to the induction of syncytia in PPRV infected cells. In the context of the characterization of the virulent lineage IV strain PPRV Kurdistan 2011, isolated from wild goats from the Kurdistan region in Iraq, we observed that both PPRV Kurdistan 2011 and the PPRV Nigeria 75/1 vaccine strain led to induction of large syncytia in Vero-dogSLAM cells within 48 h whereas both failed to induce detectable cell-cell fusion events in two Vero cell lines of differing passage histories. We were unable to detect syncytium formation in transiently transfected cells expressing PPRV F or H alone whereas co-expression of F and H induced large syncytia - in Vero-dogSLAM cells only. In Vero_Montpellier cells expressing PPRV F and H, fused cells were rarely detectable indicating that PPRV mediated cell fusion activity is impaired in this cell line. Surprisingly, on Vero-dogSLAM cells the vaccine strain grew to titers of 10^5.25 TCID₅₀/ml, whereas infectious virus yield was about 200-fold higher on Vero_Montpellier and Vero-76 cells. In contrast, the virulent Kurdistan 2011 strain grew to a maximum titer of 10^7.0 TCID₅₀/ml on Vero-dogSLAM cells and only 10^4.5 TCID50/ml on normal Vero cells. This was as expected since Vero cells lacking the SLAM receptor for PPRV are regarded as not so permissive for infection. To elucidate the divergent productive replication behaviour of PPRV Nigeria 75/1 vaccine strain on Vero vs Vero-dogSLAM cells, we examined whether intracellular transport and/or maturation of the viral envelope glycoproteins F and H might be implicated with this phenomenon. The results indicate that F in contrast to the H glycoprotein matures inefficiently during intracellular transport in Vero_Montpellier cells, thus leading to an absence of detectable syncytia formation. However, in the case of the PPRV Nigeria 75/1 vaccine strain this did not impair efficient virus assembly and release.

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.

Evolutionary dynamics of recent peste des petits ruminants virus epidemic in China during 2013-2014

Peste des petits ruminants virus (PPRV) causes a highly contagious disease, peste des petits ruminants (PPR), in sheep and goats which has been considered as a serious threat to the local economy in Africa and Asia. However, the in-depth evolutionary dynamics of PPRV during an epidemic is not well understood. We conducted phylogenetic analysis on genomic sequences of 25 PPRV strains from China 2013-2014 outbreaks. All these strains clustered into a novel clade in lineage 4. An evolutionary rate of 2.61 × 10-6 nucleotide substitutions per site per day was estimated, dating the most recent common ancestor of PPRV China 2013-2014 strains to early August 2013. Transmission network analysis revealed that all the virus sequences could be grouped into five clusters of infection, suggesting long-distance animal transmission play an important role in the spread of PPRV in China. These results expanded our knowledge for PPRV evolution to achieve effective control measures.

M protein is sufficient for assembly and release of Peste des petits ruminants virus-like particles

Peste des petits ruminants virus (PPRV), belonging to paramyxoviruses, has six structure proteins (such as matrix protein (M), nucleocapsid proteins (N), fusion protein (F) and hemagglutinin protein (H)) and could cause high morbidity and mortality in sheep and goats. Although a vaccine strain of PPRV has been rescued and co-expression of M and N could yield PPRV-like particles, the roles of structure proteins in virion assembly and release have not been investigated in detail. In this study, plasmids carrying PPRV cDNA sequences encoding the N, M, H, and F proteins were expressed in Vero cells. The co-expression of all four proteins resulted in the release of virus-like particles (VLPs) with similar release efficiency to that of authentic virions. Moreover, the co-expression of M together with F also resulted in efficient VLPs release. In the absence of M protein, the expression of no combination of the other proteins resulted in particle release. In summary, a VLPs production system for PPRV has been established and M protein is necessary for promoting the assembly and release of VLPs, of which the predominant protein is M protein. Further study will be focused on the immunogenicity of the VLPs.

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.

Genetic detection of peste des petits ruminants virus under field conditions: a step forward towards disease eradication

BACKGROUND

The devastating viral disease of small ruminants namely Peste des petits ruminants (PPR) declared as target for "Global Eradication" in 2015 by the Food and Agriculture Organization (FAO) and the World Organization for Animal Health (OIE). For a successful eradication campaign, molecular diagnostic tools are preferred for their specificity, efficacy and robustness to compliment prophylactic measures and surveillance methods. However, molecular tools have a few limitations including, costly equipment, multi-step template preparation protocols, target amplification and analysis that restrict their use to the sophisticated laboratory settings. As reverse transcription-loop mediated isothermal amplification assay (RT-LAMP) has such an intrinsic potential for point of care diagnosis, this study focused on the genetic detection of causative PPR virus (PPRV) in field conditions. It involves the use of a sample buffer that can precipitate out virus envelope and capsid proteins through ammonium sulphate precipitation and exposes viral RNA, present in the clinical sample, to the LAMP reaction mixture.

RESULTS

The test was evaluated using 11 PPRV cultures, and a total of 46 nasal swabs (n = 32 collected in the field outbreaks, n = 14 collected from experimentally inoculated animals). The RT-LAMP was compared with the reverse transcription-PCR (RT-PCR) and real-time quantitative RT-PCR (RT-qPCR) for its relative specificity, sensitivity and robustness. RT-LAMP detected PPRV in all PPRV cultures in or less than 30 min. Its detection limit was of 0.0001TCID50 (tissue culture infective dose-50) per ml with 10-fold higher sensitivity than that of RT-PCR. In 59.4% of the field samples, RT-LAMP detected PPRV within 35-55 min. The analytical sensitivity and specificity of the RT-LAMP were equivalent to that of the RT-qPCR. The time of detection of PPRV decreased by at least forty minutes or 3-4 h in case of in the RT-LAMP as compared with the RT-qPCR and the RT-PCR, respectively.

CONCLUSIONS

The sensitive and specific RT-LAMP test developed in this study targeting a small fragment of the N gene of PPRV is a rapid, reliable and applicable molecular diagnostic test of choice under the field conditions. RT-LAMP requiring minimal training offers a very useful tool for PPR diagnosis especially during the "Global PPR Eradication Campaign".

Molecular evolution of peste des petits ruminants virus

Sequence data will increase understanding of virus evolution, adaptability, and pathogenicity.

Despite safe and efficacious vaccines against peste des petits ruminants virus (PPRV), this virus has emerged as the cause of a highly contagious disease with serious economic consequences for small ruminant agriculture across Asia, the Middle East, and Africa. We used complete and partial genome sequences of all 4 lineages of the virus to investigate evolutionary and epidemiologic dynamics of PPRV. A Bayesian phylogenetic analysis of all PPRV lineages mapped the time to most recent common ancestor and initial divergence of PPRV to a lineage III isolate at the beginning of 20th century. A phylogeographic approach estimated the probability for root location of an ancestral PPRV and individual lineages as being Nigeria for PPRV, Senegal for lineage I, Nigeria/Ghana for lineage II, Sudan for lineage III, and India for lineage IV. Substitution rates are critical parameters for understanding virus evolution because restrictions in genetic variation can lead to lower adaptability and pathogenicity.

Mapping the evolutionary trajectories of morbilliviruses: what, where and whither

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Morbilliviruses are important human and animal pathogens.

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Measles virus is the prototype and is the most infectious human pathogen on earth.

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Live attenuated vaccines have been used to control the infections.

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Rinderpest virus is the second virus to be eradicated from earth.

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New morbilliviruses have been identified in cats and vampire bats.

Morbilliviruses are pathogens of humans and other animals. Live attenuated morbillivirus vaccines have been used to end endemic transmission of measles virus (MV) in many parts of the developed world and to eradicate rinderpest virus. Entry is mediated by two different receptors which govern virus lymphotropism and epitheliotropism. Morbillivirus transmissibility is unparalleled and MV represents the most infectious human pathogen on earth. Their evolutionary origins remain obscure and their potential for adaption to new hosts is poorly understood. It has been suggested that MV could be eradicated. Therefore it is imperative to dissect barriers which restrict cross species infections. This is important as ecological studies identify novel morbilliviruses in a vast number of small mammals and carnivorous predators.

Genetic Characterization of a Novel Mutant of Peste Des Petits Ruminants Virus Isolated from Capra ibex in China during 2015

Peste des petits ruminants virus (PPRV) is the causative agent of peste des petits ruminants (PPR). The spread of PPR often causes severe economic losses. Therefore, special attention should be paid to the surveillance of PPR emergence, spread, and geographic distribution. Here we describe a novel mutant of PPRV China/XJBZ/2015 that was isolated from Capra ibex in Xinjiang province in China 2015. The sequence analysis and phylogenetic assessment indicate that China/XJBZ/2015 belongs to lineage IV, being closely related to China/XJYL/2013 strain. Interestingly, the V protein sequence of China/XJBZ/2015 showed lower homology with other Chinese PPRVs isolated during 2013 to 2014 (94%~95%), whereas it shared 100% identity with three Tibet strains isolated in China 2007. The 3′ UTR, V gene, and C gene were determined to be highly variable. Besides, 29 PPR genomic sequences available in GenBank were analyzed in this study. It is the first time to use PPRV genomic sequences to classify the different lineages which confirmed the lineage clustering of PPRVs using N gene 255 bp fragments and F gene 322 bp fragments. In conclusion, our findings indicate that the PPRVs continue to evolve in China, and some new mutations have emerged.

Peste des petits ruminants

Peste des petits ruminants virus causes a highly infectious disease of small ruminants that is endemic across Africa, the Middle East and large regions of Asia. The virus is considered to be a major obstacle to the development of sustainable agriculture across the developing world and has recently been targeted by the World Organisation for Animal Health (OIE) and the Food and Agriculture Organisation (FAO) for eradication with the aim of global elimination of the disease by 2030. Fundamentally, the vaccines required to successfully achieve this goal are currently available, but the availability of novel vaccine preparations to also fulfill the requisite for differentiation between infected and vaccinated animals (DIVA) may reduce the time taken and the financial costs of serological surveillance in the later stages of any eradication campaign. Here, we overview what is currently known about the virus, with reference to its origin, updated global circulation, molecular evolution, diagnostic tools and vaccines currently available to combat the disease. Further, we comment on recent developments in our knowledge of various recombinant vaccines and on the potential for the development of novel multivalent vaccines for small ruminants.

Genome characterization and phylogenetic analysis of a lineage IV peste des petits ruminants virus in southern China

Since 2013, the second outbreak of peste des petits ruminants (PPR) caused by Peste des petits ruminants virus (PPRV) has spread over more than 20 provinces, municipalities, and autonomous regions in China, resulting in major economic losses for livestock industry. In 2014, we encountered a clinical PPR case on a goat farm in Guangdong province, southern China. The complete genome of this PPRV strain, named CH/GDDG/2014, was sequenced to determine its similarities and differences with other strains. The CH/GDDG/2014 genome comprised 15,954 nucleotides (six nucleotides more than classical PPRVs identified before 2013, but complying with the rule of six) with six open reading frames encoding nucleocapsid protein, phosphoprotein, matrix protein, fusion protein, hemagglutinin, and large polymerase protein, respectively. The whole-genome-based alignment analysis indicated that CH/GDDG/2014 had the most proximate consensus (99.8 %) to China/XJYL/2013 and the least consensus (87.2 %) to KN5/2011. The phylogenetic analysis showed that CH/GDDG/2014 was clustered in one branch (lineage IV) with other emerging strains during the second outbreak. This study is the first report describing the whole-genome sequence of PPRV in Guangdong province, southern China and also suggests the PPR outbreak may be closely related to illegal cross-regional importation of goats.

Peste des petits ruminants in Pakistan; past, present and future perspectives

Peste des petits ruminants (PPR) is considered to be one of the main constraints to enhancing the productivity of goats and sheep in regions where it is present and becoming endemic. PPR was recognized in Pakistan in early 1990s but got importance during the Participatory Disease Surveillance (PDS) of Rinderpest Eradication Campaign. Lot of research work has been initiated during last decade towards disease epidemiology, risk factor recognition, laboratory diagnosis, vaccination and demonstration of control strategies. Although there are ongoing projects working towards the progressive control of the disease in country yet there is need to have a national level control program for PPR. Also there is need to have comprehensive social economic surveys, disease hot spot recognition and identification of role of other species in disease transmission. With combined efforts of local and national authorities and political will, there is high likelihood that this devastating disease can be controlled and eventually eradicated in near future.

Complete genome sequence of a lineage I peste des petits ruminants virus isolated in 1969 in west Africa

We report the complete genome sequence of a lineage I peste des petits ruminants virus (E32/1969) isolated in a Senegalese laboratory in 1969. This is the earliest peste des petits ruminants virus of any lineage sequenced to date and only the second lineage I virus available in public databases.

Emergence of Lineage IV Peste des Petits Ruminants Virus in Ethiopia: Complete Genome Sequence of an Ethiopian Isolate 2010

Isolates of peste des petits ruminants virus (PPRV) can be segregated genetically into four lineages. For decades, lineages I-III have been reported across Africa whilst lineage IV has predominantly circulated across Asia. However, the lineage distribution is currently changing in Africa. Importantly, full genome sequence data for African field isolates have been lacking. Here, we announce the first complete genome sequence of a field isolate of peste des petits ruminants virus (PPRV) from East Africa. This isolate was derived from the intestine of a goat suffering from severe clinical disease during the 2010 outbreak in Ethiopia. The full genome sequence of this isolate, PPRV Ethiopia/2010, clusters genetically with other lineage IV isolates of PPRV, sharing high levels of sequence identity across the genome. Further, we have carried out a phylogenetic analysis of all of the available African partial N gene and F gene PPRV sequences to investigate the epidemiology of PPRV with a focus on the emergence of different lineages of PPRV in Africa.

Complete Genome Sequence of a Novel Variant Strain of Peste des Petits Ruminants Virus, China/XJYL/2013

Here, we announce the complete genome sequence of a novel variant strain of peste des petits ruminants virus, termed China/XJYL/2013. The genome is 15,954 nucleotides long with a 6-nucleotide insertion in the 5′ untranslated region of the F gene. This strain is phylogenetically classified as a lineage IV virus.

Full genome sequence of a peste des petits ruminants virus (PPRV) from Ghana

The full genome of a peste des petits ruminants virus (PPRV) isolated from a sheep lung sample collected in Ghana, Western Africa, in 2010, has been sequenced. Phylogenetic analysis demonstrated that the virus clustered within the lineage II clade while comparison of its full genome with those of other PPRV strains revealed the highest identity (96.6 %) at a nucleotide level with the PPRV strain Nigeria/76/1. This is the first full genome sequence generated for a PPRV lineage II isolated since 1976.

Diagnosis and control of peste des petits ruminants: a comprehensive review

Peste des petits ruminants (PPR) is an acute, highly contagious, world organization for animal health (OIE) notifiable and economically important transboundary viral disease of sheep and goats associated with high morbidity and mortality and caused by PPR virus. PPR is considered as one of the main constraints in augmenting the productivity of small ruminants in developing countries and particularly severely affects poor farmer's economy. The disease is clinically manifested by pyrexia, oculo-nasal discharges, necrotizing and erosive stomatitis, gastroenteritis, diarrhoea and bronchopneumonia. The disease can be diagnosed from its clinical signs, pathological lesions, and specific detection of virus antigen/antibodies/genome in the clinical samples by various serological tests and molecular assays. PPR is the one of the priority animal diseases whose control is considered important for poverty alleviation in enzootic countries. Availability of effective and safe live attenuated cell culture PPR vaccines and diagnostics have boosted the recently launched centrally sponsored control programme in India and also in other countries. This review article primarily focus on the current scenario of PPR diagnosis and its control programme with advancement of research areas that have taken place in the recent years with future perspectives.

Prokaryotic expression of f protein from PPRV and characterization of its polyclonal antibody

The goal of this study was to evaluate the specificity of a polyclonal antibody against the F protein from Peste des petits ruminants virus (PPRV). A pET30a/F prokaryotic expression vector was successfully constructed and its recombinant protein was expressed. The result of Western blot analysis showed that the fusion protein pET30a/F possessed good immunoreactivity and the purified recombinant protein was then used as the antigen to raise anti-pET30a/F polyclonal antibody in rabbits. The polyclonal antibody titer against the recombinant F protein was confirmed by indirect ELISA, and the protein's specificity against pET30/F polyclonal antibody was confirmed by both Western blot and indirect immunofluorescence assay in transfected cells. In short, we obtained the high-level expression of recombinant F protein as well as high titers of rabbit polyclonal antibody specificity against F protein in pCAGGS/F transfected cells. This special polyclonal antibody offers a valuable and useful tool for further study of the pathogenesis of PPRV early infection and the structural and functional characterization of PPRV F protein.

Characterization of ovine Nectin-4, a novel peste des petits ruminants virus receptor

Small ruminants infected with peste des petits ruminants virus exhibit lesions typical of epithelial infection and necrosis. However, the only established host receptor for this virus is the immune cell marker signaling lymphocyte activation molecule (SLAM). We have confirmed that the ovine Nectin-4 protein, when overexpressed in epithelial cells, permits efficient replication of PPRV. Furthermore, this gene was predominantly expressed in epithelial tissues and encoded by multiple haplotypes in sheep breeds from around the world.

Early events following experimental infection with Peste-Des-Petits ruminants virus suggest immune cell targeting

Peste-des-petits ruminants virus (PPRV) is a viral pathogen that causes a devastating plague of small ruminants. PPRV is an economically significant disease that continues to be a major obstacle to the development of sustainable agriculture across the developing world. The current understanding of PPRV pathogenesis has been heavily assumed from the closely related rinderpest virus (RPV) and other morbillivirus infections alongside data derived from field outbreaks. There have been few studies reported that have focused on the pathogenesis of PPRV and very little is known about the processes underlying the early stages of infection. In the present study, 15 goats were challenged by the intranasal route with a virulent PPRV isolate, Côte d'Ivoire '89 (CI/89) and sacrificed at strategically defined time-points post infection to enable pre- and post-mortem sampling. This approach enabled precise monitoring of the progress and distribution of virus throughout the infection from the time of challenge, through peak viraemia and into a period of convalescence. Observations were then related to findings of previous field studies and experimental models of PPRV to develop a clinical scoring system for PPRV. Importantly, histopathological investigations demonstrated that the initial site for virus replication is not within the epithelial cells of the respiratory mucosa, as has been previously reported, but is within the tonsillar tissue and lymph nodes draining the site of inoculation. We propose that virus is taken up by immune cells within the respiratory mucosa which then transport virus to lymphoid tissues where primary virus replication occurs, and from where virus enters circulation. Based on these findings we propose a novel clinical scoring methodology for PPRV pathogenesis and suggest a fundamental shift away from the conventional model of PPRV pathogenesis.

Assessment of the cytotoxic and anti-viral potential of aqueous extracts from different parts of Acacia nilotica (Linn) Delile against Peste des petits ruminants virus

Peste des petits ruminants virus (PPRV); a negative sense single stranded RNA enveloped virus that causes Peste des petits ruminants (PPR), is dramatically affecting the health status of ruminants all around the world resulting in extensive economical losses in livestock sector. Acacia nilotica (Linn) Delile; a tannin-rich medicinal plant distributed throughout subcontinent, is traditionally used as food for ruminants and possesses anti-viral potential against different RNA viruses. In the current study, aqueous extracts from the bark, leaves and pods of A. nilotica (Linn) Delile indica were evaluated for their cytotoxicity and anti-viral activities against PPRV by adopting MTT colorimetric assay and anti-viral assay using Vero cell line. Aqueous extract from the leaves presented significantly better (P<0.05) anti-PPRV activities in comparison to pods extract. On the contrary, bark extract did not show any anti-viral activity. The data presented in the study could pave a way toward the discovery of novel anti-viral chemicals in the plants against PPRV and other viral diseases.

Peste des petits ruminants virus detected in tissues from an Asiatic lion (Panthera leo persica) belongs to Asian lineage IV

In this study, peste des petits ruminants virus (PPRV) was detected in frozen pooled tissue samples from a dead Asiatic lion (Panthera leo persica). The samples were negative for canine distemper virus and positive for PPRV nucleic acids when tested with one-step RT-PCR using the appropriate virus-specific primers. Subsequent amplification, cloning, and sequencing of the partial nucleocapsid, matrix, and fusion genes confirmed the presence of PPRV nucleic acid. Comparative sequence and phylogenetic analyses of the structural genes of the isolated virus confirmed that the virus belonged to Asian lineage IV and was closely related to PPRV circulating in India.

Feline morbillivirus, a previously undescribed paramyxovirus associated with tubulointerstitial nephritis in domestic cats

We describe the discovery and isolation of a paramyxovirus, feline morbillivirus (FmoPV), from domestic cat (Felis catus). FmoPV RNA was detected in 56 (12.3%) of 457 stray cats (53 urine, four rectal swabs, and one blood sample) by RT-PCR. Complete genome sequencing of three FmoPV strains showed genome sizes of 16,050 bases, the largest among morbilliviruses, because of unusually long 5' trailer sequences of 400 nt. FmoPV possesses identical gene contents (3'-N-P/V/C-M-F-H-L-5') and is phylogenetically clustered with other morbilliviruses. IgG against FmoPV N protein was positive in 49 sera (76.7%) of 56 RT-PCR-positive cats, but 78 (19.4%) of 401 RT-PCR-negative cats (P < 0.0001) by Western blot. FmoPV was isolated from CRFK feline kidney cells, causing cytopathic effects with cell rounding, detachment, lysis, and syncytia formation. FmoPV could also replicate in subsequent passages in primate Vero E6 cells. Infected cell lines exhibited finely granular and diffuse cytoplasmic fluorescence on immunostaining for FmoPV N protein. Electron microscopy showed enveloped virus with typical "herringbone" appearance of helical N in paramyxoviruses. Histological examination of necropsy tissues in two FmoPV-positive cats revealed interstitial inflammatory infiltrate and tubular degeneration/necrosis in kidneys, with decreased cauxin expression in degenerated tubular epithelial cells, compatible with tubulointerstitial nephritis (TIN). Immunohistochemical staining revealed FmoPV N protein-positive renal tubular cells and mononuclear cells in lymph nodes. A case-control study showed the presence of TIN in seven of 12 cats with FmoPV infection, but only two of 15 cats without FmoPV infection (P < 0.05), suggesting an association between FmoPV and TIN.

Molecular characterization and phylogenetic study of peste des petits ruminants viruses from north central states of Nigeria

BACKGROUND

Peste des petits ruminants is an endemic disease of sheep and goats in Nigeria and vaccination has been the method of control but sporadic outbreaks have been reported. This study was carried out to characterize PPR viruses from outbreaks in 2007 and 2009 from Kaduna and Plateau States.

RESULTS

Of the 33 clinical samples analysed, 51.52% (n = 17) were positive for F protein gene primers (F1/F2). All the samples had a sequence similarity of 98-100% among them and 92-97% with the reference vaccine (Nig 75/1) strain. The deduced amino acid homology ranges between 96.3-99.7%. Phylogenetically all the Nigerian sequences cluster with Nig 75/1 and Nig 76/1 in lineage 1.

CONCLUSIONS

PPR is still a problem in Kaduna and Plateau States of Nigeria. The strains involved were genetically closely related to the vaccine strain (Nig 75/1) used in the country. Based on this study, the continued outbreaks in the Country is not due to the efficacy of the vaccine. Therefore, to achieve effective control and possibly eradication of PPR in Nigeria, the current control strategies should be revisited.

Asian lineage of peste des petits ruminants virus, Africa

Interest in peste des petits ruminants virus (PPRV) has been stimulated by recent changes in its host and geographic distribution. For this study, biological specimens were collected from camels, sheep, and goats clinically suspected of having PPRV infection in Sudan during 2000-2009 and from sheep soon after the first reported outbreaks in Morocco in 2008. Reverse transcription PCR analysis confirmed the wide distribution of PPRV throughout Sudan and spread of the virus in Morocco. Molecular typing of 32 samples positive for PPRV provided strong evidence of the introduction and broad spread of Asian lineage IV. This lineage was defined further by 2 subclusters; one consisted of camel and goat isolates and some of the sheep isolates, while the other contained only sheep isolates, a finding with suggests a genetic bias according to the host. This study provides evidence of the recent spread of PPRV lineage IV in Africa.

Sequence and phylogenetic analyses of the structural genes of virulent isolates and vaccine strains of peste des petits ruminants virus from India

Peste des petits ruminants (PPR) is an acute, highly contagious, notifiable and economically important transboundary viral disease of sheep and goats. In this study, sequence and phylogenetic analyses of structural protein genes, namely the nucleocapsid (N), the matrix (M), the fusion (F) and the haemagglutinin (H) coding sequences of virulent and vaccine strains of PPR virus (PPRV), were undertaken to determine the genetic variations between field isolates and vaccine strains. The open reading frame (ORF) of these genes of the isolates/strains was amplified by RT-PCR, cloned and sequenced. The ORF of N, M, F and H genes was 1578, 1008, 1641 and 1830 nucleotides (nt) in length and encodes polypeptides of 525, 335, 546 and 609 amino acids (aa), respectively, as reported earlier. Comparative sequence analyses of these four genes of isolates/strains were carried out with published sequences. It revealed an identity of 97.7-100% and 97.7-99.8% among the Asian lineage IV and 89.6-98.7% and 89.8-98.9% with other lineages of PPRV at nt and aa levels, respectively. The phylogenetic analyses of these isolates based on the aa sequences showed that all the viruses belonged to lineage IV along with other Asian isolates. This is in agreement with earlier observations that only PPRV lineage IV is in circulation in India since the disease was first reported. Further, sequence analysis of the thermostable/thermo-adapted vaccine strains showed no significant changes in the functional or structural surface protein-coding gene sequences. It is important to monitor the circulation of the PPRV in susceptible animals by H gene-based sequence comparisons in addition to the F gene- and N gene-based approaches to identify the distribution and spread of virus in the regular outbreaks that occur in endemic countries like India.