Peste des Petits Ruminants (PPR) Outbreak in Tajikistan

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.

Peste des petits ruminants virus in Heilongjiang province, China, 2014

During March 25–May 5, 2014, we investigated 11 outbreaks of peste des petits ruminants in Heilongjiang Province, China. We found that the most likely source of the outbreaks was animals from livestock markets in Shandong. Peste des petits ruminants viruses belonging to lineages II and IV were detected in sick animals.

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 vaccine and vaccination in India: sharing experience with disease endemic countries

Peste des petits ruminants, a viral disease of small ruminants, the control of which is important for poverty alleviation and to ensure livelihood security in Asia, Middle East and Africa. In recognition of these issues, we developed and applied vaccine and diagnostics to demonstrate effective control of PPR during preceding 6 years in a sub-population of small ruminants in India. Two south Indian states, namely Andhra Pradesh and Karnataka, strongly indicated possibility of PPR control with more than 90 % reduction in number of reported outbreaks of PPR, mostly through mass vaccination. Similarly, the situation at the national level also demonstrated a decline of more than 75 % in the number of reported outbreaks. Sharing these experiences may motivate other countries for similar initiatives leading to progressive control of PPR, which is in line with the initiatives of the organizations like FAO/OIE and the recent platforms on global PPR research alliance.

Peste des petits ruminants outbreaks in White Nile State, Sudan

Eight outbreaks of peste des petits ruminants in sheep and goats were reported in White Nile State, Sudan, between 2008 and 2009. A mortality rate of 4.2% was reported across the different outbreaks. Clinically the disease was characterised by high fever, ocular and nasal discharge, pneumonia, ulceration of the mucous membranes, diarrhoea and death. The postmortem findings included necrotic lesions in the mouth and gastrointestinal tract, and swollen, oedematous lymph nodes associated with the lungs and intestine. Of the 209 serum samples tested by competitive enzyme-linked immunosorbent assay, 113 (54%) were found positive. Peste des petits ruminants virus was confirmed in tissues, nasal swabs and blood samples by immunocapture enzyme-linked immunosorbent assay, reverse-transcription polymerase chain reaction and isolation of the virus in culture of lamb testicle cells.

Detection and Genetic Characterization of Lineage IV Peste Des Petits Ruminant Virus in Kazakhstan

Peste des petits ruminant (PPR) is endemic in many Asian countries with expansion of the range in recent years including across China during 2013-2014 (OIE, 2014). Till the end of 2014, no cases of PPR virus (PPRV) were officially reported to the Office Internationale des Epizooties (OIE) from Kazakhstan. This study describes for the first time clinicopathological, epidemiological and genetic characterization of PPRV in 3 farm level outbreaks reported for the first time in Zhambyl region (oblast), southern Kazakhstan. Phylogenetic analysis based on partial N gene sequence data confirms the lineage IV PPRV circulation, similar to the virus that recently circulated in China. The isolated viruses are 99.5-99.7% identical to the PPRV isolated in 2014 from Heilongjiang Province in China and therefore providing evidence of transboundary spread of PPRV. There is a risk of further maintenance of virus in young stock despite vaccination of adult sheep and goats, along livestock trade and pastoral routes, threatening both small livestock and endangered susceptible wildlife populations throughout Kazakhstan.

Serological Detection of Antibodies to Peste des Petits Ruminants Virus in Large Ruminants

Peste des petits ruminants (PPR) is an economically important disease of small ruminants with a rapidly expanding geographical distribution. Peste des petits ruminants virus may manifest in a variety of ways with disease ranging from acute to subclinical. We investigated the exposure of large ruminants to PPRV in areas where the virus is endemic in the small ruminant population by assessing the serological status of groups of animals. This study focused on the Punjab province of Pakistan as an area where the virus is endemic and where mixed farming practices occur enabling close interactions between small and large ruminant populations. An overall PPR seropositivity was detected in 10.0% of cattle and 14.16% of buffaloes. Following an assessment of serological profiles in large ruminants within different age groups, a maximum seroprevalence was observed in cattle (17.5%) and buffaloes (22.5%) over 2 years of age indicating the potential utility of sampling large ruminant populations for PPR serosurveillance. The large ruminants sampled between one and two years of age had similar levels of seropositivity within populations with 11.2% and 16.2% of animals being seropositive, respectively. Current PPR vaccination strategies do not enable the differentiation between infected and vaccinated small ruminants, and as such, the serological surveillance of sheep and goats is of little value. When considering eradication programmes for PPRV, this factor is of great significance. However, where large and small ruminants are farmed together, serological surveillance of large ruminants may provide a snapshot of virus infection within populations where mild disease is present or where small ruminants are regularly vaccinated.

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

Peste-des-petits-ruminants (PPR), a major small ruminant transboundary animal disease, is endemic in Nigeria. Strains of the causal agent, peste-des-petits-ruminants virus (PPRV), have been differentiated into four genetically distinct lineages based on the partial sequence of the virus nucleoprotein (N) or fusion (F) genes. Peste-des-petits-ruminants virus strains that were identified initially in Africa were grouped into lineages I, II and III and viruses from Asia were classified as lineage IV and referred to as the Asian lineage. Many recent reports indicate that the Asian lineage is now also present in Africa. With this in mind, this study was conducted to reassess the epidemiology of PPRV in Nigeria. A total of 140 clinical samples from 16 sheep and 63 goats with symptoms suggestive of PPR were collected from different states of Nigeria during a four-year period (2010-2013). They were analysed by the amplification of fragments of the N gene. Results for 33 (42%) animals were positive. The phylogenetic analysis of the N gene sequences with those available in GenBank showed that viruses that were detected belong to both lineage II and IV. Based on an analysis of the N gene sequences, the lineage IV isolates grouped into two clades, one being predominant in the north-eastern part of the country and the other found primarily in the southern regions of the country. This study reports the presence of PPRV Asian lineage IV in Nigeria for the first time.

First serological and molecular evidence of PPRV occurrence in Ghardaïa district, center of Algeria

In February 2012, an outbreak of peste des petits ruminants (PPR) was suspected in Ghardaïa district at the center of Algeria. Clinical, serological, and molecular investigations were performed to confirm the occurrence of PPRV. The overall morbidity, mortality, and case fatality rates of the ten flocks investigated were 12.2, 2.5, and 20.3 %, respectively. At the flock level, positivity to PPR was 100, 90, and 100 % by competitive ELISA (c-ELISA), RT-PCR of blood samples, and oculo-nasal swabs, respectively. At the individual levels, the present study showed that out of 186 samples collected from the same animals 17/62 (27.41 %), 14/62 (22.85 %), and 36/62 (58.06 %) were positive by c-ELISA, RT-PCR of blood samples, and RT PCR of oculo-nasal swabs, respectively. The positivity of PPR was significantly higher using RT-PCR of oculo-nasal swabs than c-ELISA and RT-PCR of blood samples. The N gene partial sequence of five PPRV-positive amplicons revealed 100 % homology among them and phylogenetically belonged to lineage IV. The sequences also showed similarity range of 97-99 % with the strains implicated in the Moroccan and Tunisian outbreaks, however, suggesting that a similar strain is circulating across this area of the Maghreb and highlighting the need for a regional control approach.

Peste des Petits Ruminants Viruses Re-emerging in China, 2013-2014

Re-emergence of peste des petits ruminants (PPR) was officially reported in Xinjiang Uygur Autonomous Region in north-western China in November 2013, and then along with the movements of goats and sheep, this disease rapidly spread to other provinces, autonomous regions and municipalities (P/A/M) of China. A total of 256 PPR-affected counties in 22 P/A/M were identified up to September 2014. Phylogenetic analysis revealed that the current circulating strains and Tibet strains isolated previously in 2007, both belonged to lineage IV but in different sub-branches. Nevertheless, compared with the Tibet strains, the current circulating strains shared high degree of genetic homology with those from Pakistan and Tajikistan.

Impact and Epidemiological Investigations into the Incursion and Spread of Peste des Petits Ruminants in the Comoros Archipelago: An Increased Threat to Surrounding Islands

Late October 2012, a great number of deaths of unknown origin occurred in goat herds in the suburbs of Ngazidja, located in the Comoros archipelago. Few weeks later, laboratory testing requested by the animal health authorities resulted in the identification of peste des petits ruminants (PPR) infection. Notably, the Index case could be attributed to a sick goat imported from Tanzania. Viral isolation was successful from the lungs leading to the whole N nucleoprotein gene sequencing. Phylogenetic analysis revealed that the strain belongs to the lineage III which includes strains of eastern African origin. In addition, to evaluate the impact of PPR on the Comorian indigenous domesticated ruminant population, a cross-sectional PPR serological survey was conducted between April and July 2013. A low overall PPRV antibody prevalence 2.24% (95% CI [1.38; 3.08]) was detected with a Grande Comore prevalence of 3.34% (IC = [2.09; 4.63]) with a limited spread of the disease mainly due to farm practices such as limited contacts between farm animals and rapid slaughtering of sick animals.

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.

Molecular characterization of peste-des-petits ruminants virus (PPRV) isolated from an outbreak in the Indo-Bangladesh border of Tripura state of North-East India

Peste-des-petits- ruminants (PPR) is a highly contagious and devastating disease of goats and sheep. Although India is endemic for PPR, Tripura, a state in North East India has never been reported confirmed PPR outbreaks. Recently, an outbreak of PPR occurred in non-descript goats at the Sabroom town of Tripura state in North-East India in June, 2013. The causative agent, PPR virus (PPRV) was confirmed by sandwich ELISA, virus isolation and N gene based RT-PCR and sequencing. The sequence and phylogenetic analysis confirmed the involvement of lineage IV PPR virus in the outbreak. The outbreak viruses from Tripura state were clustered mainly with circulating viruses from Bangladesh, India, China, Pakistan, Tajikistan, Dubai and Kurdistan. However, the nucleotide sequence homology ranged from 99.2 to 99.6% with the PPR strains circulating in Bangladesh during 2011 and 2012 whereas 95.5-98% homology has been observed with the viruses from India and other countries. These findings suggest the transboundary circulation of PPR virus between India and Bangladesh border, which warrant immediate vaccination across the international border to create an immune belt.

Dried fluid spots for peste des petits ruminants virus load evaluation allowing for non-invasive diagnosis and genotyping

BACKGROUND

Active surveillance of peste des petits ruminants (PPR) should ease prevention and control of this disease widely present across Africa, Middle East, central and southern Asia. PPR is now present in Turkey at the gateway to the European Union. In Bangladesh, the diagnosis and genotyping of PPR virus (PPRV) may be hampered by inadequate infrastructures and by lack of proper clinical material, which is often not preserved under cold chain up to laboratories. It has been shown previously that Whatman® 3MM filter paper (GE Healthcare, France) preserves the nucleic acid of PPRV for at least 3 months at 32°C.

RESULTS

In this study, we demonstrate the performances of filter papers for archiving RNA from local PPRV field isolates for further molecular detection and genotyping of PPRV, at -70°C combined with ambient temperature, for periods up to 16 months. PPR-suspected live animals were sampled and their blood and nasal swabs were applied on filter papers then air dried. Immediately after field sampling, RT-PCR amplifying a 448-bp fragment of the F gene appeared positive for both blood and nasal swabs when animals were in febrile stage and only nasal swabs were detected positive in non-febrile stage. Those tested positive were monitored by RT-PCR up to 10 months by storage at -70°C. At 16 months, using real time RT-PCR adapted to amplify the N gene from filter paper, high viral loads could still be detected (~2 x 10(7) copy numbers), essentially from nasal samples. The material was successfully sequenced and a Bayesian phylogenetic reconstruction achieved adequate resolution to establish temporal relationships within or between the geographical clusters of the PPRV strains.

CONCLUSIONS

This clearly reveals the excellent capacity of filter papers to store genetic material that can be sampled using a non-invasive approach.

WITHDRAWN: Identification of peste-des-petits ruminants virus (PPRV) lineage IV, the Asian lineage, in Nigeria and co-circulation with PPRV lineage II

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Complete Genome Sequence of a Field Strain of Peste des Petits Ruminants Virus Isolated during 2010-2014 Epidemics in Senegal

Peste des petits ruminants virus (PPRV) infection is expanding and results in regular epizootic activities in Africa, the Middle East, and Asia. Here, we report the complete genome sequence of a field strain of PPRV isolated in Senegal (SnDk11I13) in 2013.

Virus excretion and antibody dynamics in goats inoculated with a field isolate of peste des petits ruminants virus

A field isolate of peste des petits ruminants virus (PPRV) from an outbreak in Tibet, China, was inoculated into goats to investigate the dynamics of virus excretion and antibody production. Further, animals received PPRV vaccine strain Nigeria 75/1. Ocular, nasal and oral samples were tested for the presence of virus antigen by one-step real-time qualitative RT-PCR (qRT-PCR); competitive ELISA (c-ELISA) was used for the measurement of specific antibodies against PPRV. Virus particles could be detected as early as day 3 post-inoculation (pi) and virus excretion lasted for up to day 26 pi. All four goats inoculated with the PPRV field isolate were seropositive as early as day 10 pi. In animals inoculated with the vaccine strain, antibody was detected at day 14 pi, and levels of neutralizing antibodies remained above the protection threshold level (1 : 8) for 8 months. Both virus particles and neutralizing antibodies were detected earlier in goats challenged with the field isolate than in those receiving the vaccine strain.

Emergence of peste des petits ruminants virus lineage IV in Ismailia Province, Egypt

Peste des petits ruminants (PPR) is an acute, highly contagious fatal disease of small ruminants characterized by high fever, ocular and nasal discharge, pneumonia, erosive stomatitis and severe enteritis that ultimately results in high mortalities. Peste des petits ruminants virus (PPRV) is widely distributed and endemic in several African, middle eastern and south Asian countries and it poses a threat to European countries. Egyptian veterinary medical authorities stated that Egypt is free from PPRV and the only measures for disease control are test and slaughter of infected population to maintain the free status. The aim of our investigation was to detect PPRV in Ismailia province as an indicator of the infection status in Egypt and perform molecular characterization of the emerging virus to gain insight into the origin of circulating virus. A total of 40 representative clinical samples, from a single goat case and goat flock in 2010 and sheep flock in 2012, were tested for PPRV by RT-PCR. About 21 (52.5%) samples were positive. The phylogenetic analysis of the detected viruses revealed circulation of PPRV lineage IV. The circulating viruses are closely related to Sudanese and Saudia Arabian strains with nucleotide identity ranged from 99.2% to 99.6%, respectively. Also, it is closely related to Moroccan 2008 viruses with identities ranged from 97.6% to 98%. Epidemiological investigation at the national level is recommended for monitoring PPRV spread and implementing an appropriate control program.

Peste des petits ruminants virus infection of small ruminants: a comprehensive review

Peste des petits ruminants (PPR) is caused by a Morbillivirus that belongs to the family Paramyxoviridae. PPR is an acute, highly contagious and fatal disease primarily affecting goats and sheep, whereas cattle undergo sub-clinical infection. With morbidity and mortality rates that can be as high as 90%, PPR is classified as an OIE (Office International des Epizooties)-listed disease. Considering the importance of sheep and goats in the livelihood of the poor and marginal farmers in Africa and South Asia, PPR is an important concern for food security and poverty alleviation. PPR virus (PPRV) and rinderpest virus (RPV) are closely related Morbilliviruses. Rinderpest has been globally eradicated by mass vaccination. Though a live attenuated vaccine is available against PPR for immunoprophylaxis, due to its instability in subtropical climate (thermo-sensitivity), unavailability of required doses and insufficient coverage (herd immunity), the disease control program has not been a great success. Further, emerging evidence of poor cross neutralization between vaccine strain and PPRV strains currently circulating in the field has raised concerns about the protective efficacy of the existing PPR vaccines. This review summarizes the recent advancement in PPRV replication, its pathogenesis, immune response to vaccine and disease control. Attempts have also been made to highlight the current trends in understanding the host susceptibility and resistance to PPR.

Induction of protective immune response against both PPRV and FMDV by a novel recombinant PPRV expressing FMDV VP1

Peste des petits ruminants (PPR) and foot-and-mouth disease (FMD) are both highly contagious diseases of small domestic and wild ruminants caused by the PPR virus (PPRV) and the FMD virus (FMDV). In this study, a recombinant PPRV expressing the FMDV VP1 gene (rPPRV/VP1) was generated and FMDV VP1 expression did not impair replication of the recombinant virus in vitro and immunogenicity in inducing neutralizing antibody against PPR in goats. Vaccination with one dose of rPPRV/VP1 induced FMDV neutralizing antibody in goats and protected them from challenge with virulent FMDV. Our results suggest that the recombinant PPRV expressing the FMDV VP1 protein is a potential dual live vectored vaccine against PPRV and FMDV.

Genetic analysis of peste des petits ruminants virus from Pakistan

Background

Peste des petits ruminants (PPR) is an endemic and highly contagious disease in small ruminants of Pakistan. Despite the fact that an effective vaccine is available, outbreaks are regularly occurring in the country. Thus so far, the diagnosis has primarily been made based on clinical outcome or serology. This study was carried out to characterize PPRV from an emerging wave of outbreaks from Punjab, Pakistan.

Results

A total of 32 blood samples from five different flocks were tested with real-time PCR for the presence of PPRV genome. The samples detected positive in real-time PCR (n = 17) were subjected to conventional PCR for the amplification of the nucleoprotein (N) gene. Phylogenetic analysis of the sequenced N genes (n = 8) indicated the grouping of all the sequences in lineage IV along with PPRV strains from Asian and Middle East. However, interestingly sequences were divided into two groups. One group of viruses (n = 7) clustered with previously characterized Pakistani isolates whereas one strain of PPRV was distinct and clustered with Saudi Arabian and Iranian strains of PPRV.

Conclusions

Results demonstrated in this study expanded the information on the genetic nature of different PPRV population circulating in small ruminants. Such information is essential to understand genetic nature of PPRV strains throughout the country. Proper understanding of these viruses will help to devise control strategies in PPRV endemic countries such as Pakistan.

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.

Complete genome sequence of a Peste des petits ruminants virus recovered from wild bharal in Tibet, China

For the first time, here we announce the complete genome sequence of a field isolate of Peste des petits ruminants virus (PPRV) derived from macerated rectal tissue of a free living bharal (Pseudois nayaur) that displayed clinical disease consistent with severe infection with PPRV. Further, we compare the full genome of this isolate, termed PPRV Tibet/Bharal/2008, with previously available PPRV genomes, including those of virus isolates from domestic small ruminants local to the area where the reported isolate was collected. The current sequence is phylogenetically classified as a lineage IV virus, sharing high levels of sequence identity with previously described Tibetan PPRV isolates. Indeed, across the entire genome, only 26 nucleotide differences (0.16% nucleotide variation) and, consequently, 9 amino acid changes were present compared to sequences of locally derived viruses.

Rescue of recombinant peste des petits ruminants virus: creation of a GFP-expressing virus and application in rapid virus neutralization test

Peste des petits ruminants virus (PPRV) causes high mortality in goats and sheep and the disease has shown a greatly increased geographic distribution over the last 15 years. It is responsible for serious socioeconomic problems in some of the poorest developing countries. The ability to create recombinant PPRV would provide a useful tool for investigating the biology of the virus and the pathology of disease, as well as for developing new vaccines and diagnostic methods. Here we report the first successful rescue of recombinant PPRV from a full-length cDNA clone of the virus genome. Successful recovery of PPRV was achieved by using a RNA polymerase II promoter to drive transcription of the full-length virus antigenome. We have used this technique to construct a virus expressing a tracer protein (green fluorescent protein, GFP). The recombinant virus replicated as well as the parental virus and could stably express GFP during at least 10 passages. The newly established reverse genetics system for PPRV provides a novel method for constructing a vaccine using PPRV as a vector, and will also prove valuable for fundamental research on the biology of the virus. We found that our recombinant virus allowed more rapid and higher throughput assessment of PPRV neutralization antibody titer via the virus neutralization test (VNT) compared with the traditional method.

A novel recombinant Peste des petits ruminants-canine adenovirus vaccine elicits long-lasting neutralizing antibody response against PPR in goats

BACKGROUND

Peste des petits ruminants (PPR) is a highly contagious infectious disease of goats, sheep and small wild ruminant species with high morbidity and mortality rates. The Peste des petits ruminants virus (PPRV) expresses a hemagglutinin (H) glycoprotein on its outer envelope that is crucial for viral attachment to host cells and represents a key antigen for inducing the host immune response.

METHODOLOGY/PRINCIPAL FINDINGS

To determine whether H can be exploited to generate an effective PPRV vaccine, a replication-competent recombinant canine adenovirus type-2 (CAV-2) expressing the H gene of PPRV (China/Tibet strain) was constructed by the in vitro ligation method. The H expression cassette, including the human cytomegalovirus (hCMV) promoter/enhancer and the BGH early mRNA polyadenylation signal, was inserted into the SspI site of the E3 region, which is not essential for proliferation of CAV-2. Infectious recombinant rCAV-2-PPRV-H virus was generated in transfected MDCK cells and used to immunize goats. All vaccinated animals produced antibodies upon primary injection that were effective in neutralizing PPRV in vitro. Higher antibody titer was obtained following booster inoculation, and the antibody was detectable in goats for at least seven months. No serious recombinant virus-related adverse effect was observed in immunized animals and no adenovirus could be isolated from the urine or feces of vaccinated animals. Results showed that the recombinant virus was safe and could stimulate a long-lasting immune response in goats.

CONCLUSIONS/SIGNIFICANCE

This strategy not only provides an effective PPR vaccine candidate for goats but may be a valuable mean by which to differentiate infected from vaccinated animals (the so-called DIVA approach).

Fatalities in wild goats in Kurdistan associated with Peste des Petits Ruminants virus

Between August 2010 and February 2011, over 750 deaths were recorded among wild goats (Capra aegagrus, the endangered progenitor of the domestic goat) in Kurdistan. Based on the clinical signs and post-mortem findings, the involvement of peste des petits ruminants virus (PPRV) was suspected. This was confirmed by laboratory analysis, and the virus was found to be closely related to a Turkish strain isolated in 2000. During the outbreak in wild goats, no disease in domestic animals was reported. Domestic ruminants in the region are routinely vaccinated with an attenuated vaccine based on the 'Nigeria/75/1' strain of PPRV. This is the first report of active PPRV infection in Kurdistan and most likely the immunity afforded by vaccination prevented spillover infections. It is therefore recommended to continue with the campaign. Conversely, there is no justification for the use of force to keep the endangered wild goats away from domestic flocks.

Tissue distribution and expression of signaling lymphocyte activation molecule receptor to peste des petits ruminant virus in goats detected by real-time PCR

In the present study, we investigated the tissue distribution and expression of signaling lymphocyte activation molecule (SLAM) in 40 tissues and organs of goats by real-time RT-PCR, in order to determine the role of these receptors in tissue tropism. SLAM mRNA was detected in all the samples investigated. The expression of SLAM mRNA was detected at high levels in spleen, mesenteric lymph node, hilar lymph node, mandibular lymph node, superficial cervical lymph node, nasal mucosa, duodenum, heart, gallbladder, thymus and blood; this is similar to the tissue tropism of peste des petits ruminant virus. However, it was surprising that expression of SLAM was low in lungs, colon and rectum which are the major sites of replication of PPRV. In addition, very low levels were detected in larynx, tongue and esophagus, which suggest the possible presence of an alternative receptor for PPRV. This study provided the first data on caprine SLAM for use in further studies of the pathogenesis of PPRV in goats.

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.

A real time RT-PCR assay for the specific detection of Peste des petits ruminants virus

Peste des petits ruminants virus (PPRV) causes a devastating disease of small ruminants present across much of Africa and Asia. Recent surveillance activities and phylogenetic analyses have suggested that the virus is an emerging problem as it is now being detected in areas previously free of the disease. As such, the virus not only is threatening small ruminant production and agricultural stability in the developing world, but also poses an economic threat to livestock in the European Union (EU) through introduction from European Turkey and North Africa. This report describes the development of a high throughput, rapid, real time RT-PCR method for the sensitive and specific detection of PPRV using robotic RNA extraction. This assay targets the nucleocapsid (N) gene of PPRV and has been shown to detect all four genetic lineages of PPRV in tissues, ocular and nasal swabs and blood samples collected in the field. The lowest detection limit achieved was approximately 10 genome copies/reaction, making this assay an ideal tool for the sensitive and rapid detection of PPRV in diagnostic laboratories.

An outbreak of peste des petits ruminants (PPR) in camels in the Sudan

In mid-August 2004, an outbreak of a previously unknown fatal disease of camels was reported to Kassala State veterinary authorities. Several areas in the state were visited during August-October 2004 to collect epidemiological data and specimens for diagnosis. Clinically the disease was characterized by sudden death of apparently healthy animals and yellowish and later bloody diarrhea and abortion. The disease outbreaks coincided with the seasonal movement of animals towards autumn green pasture. Death was always sudden and proceeded with colic and difficulty in respiration. Mortality rate ranged between 0% and 50% and vary in accordance with the area with a mean of 7.4%. More than 80% of deaths were in pregnant and recently-delivered she-camels. All age, sex and breed groups were affected but more than 50% of deaths were reported in adult animals in comparison to calves and young camels. The main post-mortem findings include lung congestion and consolidation, paleness and fragility of liver, enlarged lymph nodes and congestion and hemorrhage of small intestine and stomach. Agar gel diffusion test (AGDT), RT-PCR and virus isolation in cell culture gave positive results for peste des petits ruminants virus (PPRV), a virus belonging to the Morbillivirus, Genus, member of the family Paramyxoviridae. The effect of this new devastating disease on camel production in the affected area was discussed as well as proposals for future research.

Detection and genetic characterization of peste des petits ruminants virus in free-living bharals (Pseudois nayaur) in Tibet, China

Peste des petits ruminants (PPR) is an important viral disease of sheep and goats. The wildlife hosts of PPR, which may play an important role in the epidemiology of this disease, are not well characterized. The research was undertaken to study the infection of PPR virus (PPRV) in free-living bharals (Pseudois nayaur) in Tibet, China. In 2007, PPRV infection was confirmed in two bharals in Rutog County of Tibet based on clinical signs and detection of PPRV RNA in tissue samples. In 2008, PPRV infection was found in one bharal in Ge'gyai County of Tibet by competitive ELISA, reverse transcription-polymerase chain reaction, and sequence analysis of PPRV fusion protein (F) and nucleoprotein (N) gene segments. The PPRV variant identified in infected bharal was closely related to other circulating PPRV variants recently identified in sheep and goats from Tibet. This is the first report of PPRV infection in free-living bharals.

Peste des petits ruminants in Arabian wildlife

Recurrence of peste des petits ruminants (PPR) was diagnosed in the United Arabian Emirates in several wild ruminants confirmed by morphological, immunohistochemical, serological and molecular findings. Phylogenetic analysis revealed that the virus strain belongs to lineage IV, which is different to some previously isolated PPR strains from the Arabian Peninsula. This study shows that wild ruminants may play an important epidemiological role as virus source for domestic small ruminants.

Peste des petits ruminants virus in Tibet, China

Serologic and molecular evidence indicates that peste des petits ruminants virus (PPRV) infection has emerged in goats and sheep in the Ngari region of southwestern Tibet, People’s Republic of China. Phylogenetic analysis confirms that the PPRV strain from Tibet is classified as lineage 4 and is closely related to viruses currently circulating in neighboring countries of southern Asia.

Examples of probable host-pathogen co-adaptation/co-evolution in isolated farmed animal populations in the mountainous regions of North Vietnam

In Vietnam, for a number of specific geographical and historical reasons, the mountainous areas have preserved an exceptional diversity of wild and domestic animal species of high socioeconomic interest. This endemic genetic diversity fosters a rapid response to environmental change in mostly isolated local communities and, in particular, fosters the constant adaptation of ecosystems common to humans and farmed and wild animal populations and pathogens. During a 2-year study carried out in several mountainous regions of North Vietnam near the Chinese border, we surveyed 1697 breeders in 249 villages and gathered 5815 biological samples among the four main domesticated species of food animals: chickens, cattle, buffaloes, and goats. Serological analyses were carried out by ELISA on 726 sera in order to assess the prevalence of antibodies specific to two major diseases suspected to be present in the region: avian influenza (AI) and peste des petits ruminants (PPR). The results reported here reveal the presence of antibodies specific to AI, but not the H5N1 highly pathogenic strain, and the presence of antibodies specific to PPR, confirming that this disease, never previously described in Southeast Asia, is present in this region, with no mortality and little or no evidence of clinical cases. These are probably situations of co-evolutive epidemiological equilibrium between pathogen populations, which may have lost their virulence, and animal populations that have acquired genetic resistances over generations, either naturally or through genetic introgression from related wild species better adapted to such pathogens. These results suggest the need for more research, both short-term and, more globally, long-term.

Real-time RT-PCR assays for the rapid and differential detection of dolphin and porpoise morbilliviruses

Real-time RT-PCR (rtRT-PCR) assays for identifying and differentiating infections caused by dolphin morbillivirus (DMV) and porpoise morbillivirus (PMV) were developed by targeting the hypervariable C-terminal domain of the nucleocapsid (N) gene. Total DMV and PMV RNA extracted from infected Vero cells expressing the canine signaling lymphocyte-activation molecule (SLAM) produced positive cycle threshold (C(T)) values after the 17th and 25th cycles, respectively. The assays were then validated using infected cetacean tissue RNA. The assays were specific for either DMV or PMV and did not cross-react with canine distemper virus (CDV), phocid distemper virus (PDV), rinderpest virus (RPV), peste des petits ruminants virus (PPRV) and measles virus (MV). The glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene was targeted as control for RNA quality, and a consensus GAPDH probe that reacted with 11 different marine mammal species, generating positive C(T) values ranging from the 21st to the 37th cycle was used. The rtRT-PCR assays have advantages over conventional assays in that they are rapid, easier to scale up, and are less prone to cross-contamination and have improved the limit of detection and specificity.

Development of one-step real-time RT-PCR assay for detection and quantitation of peste des petits ruminants virus

In this study, a rapid and specific TaqMan-based, one-step real-time quantitative reverse transcription PCR (qRT-PCR) has been described for the detection of peste des petits ruminants virus (PPRV). Primers and probe were designed based on the nucleocapsid protein gene sequence. The real-time qRT-PCR assay was able to detect PPRV isolates from very distinct geographical areas (Africa, Middle East and Asia). The specificity of the assay was assessed by including rinderpest virus and other morbillivirus RNAs but none of these tested positive in the assay. The analytical sensitivity of the real-time qRT-PCR assay was achieved through the construction of an in-house PPRV cRNA for the generation of a standard curve. The detection limit of the assay was found to be 8.1 RNA copies per reaction mixture. The assay had excellent intra- and inter-assay reproducibility. In total 30 field samples were screened for the presence of PPRV by conventional RT-PCR in parallel with qRT-PCR. The detection rate increased from 46.7% to 73.3% by use of the real-time qRT-PCR. The real-time qRT-PCR assay described in this report allows the rapid, specific and sensitive laboratory detection of PPRV in tissue samples from field cases.

Long-term storage at tropical temperature of dried-blood filter papers for detection and genotyping of RNA and DNA viruses by direct PCR

In tropical countries the diagnosis of viral infections of humans or animals is often hampered by the lack of suitable clinical material and the necessity to maintain a cold chain for sample preservation up to the laboratory. This study describes the use of filter papers for rapid sample collection, and the molecular detection and genotyping of viruses when stored over long periods at elevated temperatures. Infected blood was collected on filter papers, dried and stored at different temperatures (22, 32 and 37 degrees C) for various periods (up to 9 months). Two animal viruses, African swine fever, a large double-stranded DNA virus and Peste des Petits Ruminants, a negative single-stranded RNA virus, were used to validate the method. Filter papers with dried blood containing virus or control plasmid DNA were cut in small 5mm(2) pieces and added directly to the PCR tube for conventional PCR. Nucleic acid from both viruses could still be detected after 3 months at 32 degrees C. Moreover, the DNA virus could be detected at least 9 months after conservation at 37 degrees C. PCR products obtained from the filter papers were sequenced and phylogenetic analysis carried out. The results were consistent with published sequences, demonstrating that this method can be used for virus genotyping.

The threat of peste des petits ruminants: progress in vaccine development for disease control

Peste des petits ruminants (PPR) is a highly contagious animal disease caused by a virus in the genus Morbillivirus, family Paramyxoviridae. This infection is responsible for high morbidity and mortality in sheep and goats and in some small wild ruminant species. The huge number of small ruminants, which are reared in the endemic areas makes PPR a serious disease threatening the livelihood of poor farmers. Taking advantage of the closely relationship between rinderpest and PPR viruses, the attenuated rinderpest vaccine was used in the control of PPR. It is now replaced by the homologous attenuated PPR vaccine. Unfortunately, animals that have received this vaccine cannot be distinguished serologically from infected animals. With the advent of DNA recombinant technology, efforts are being made to develop effective PPR marker vaccines to enable such differentiation and which would allow countries to implement both vaccination and disease surveillance programmes at the same time.