Olivier Kwiatek

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.

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.

Peste des petits ruminants, the next eradicated animal disease?

Peste des Petits Ruminants (PPR) is a widespread viral disease caused by a Morbillivirus (Paramyxoviridae). There is a single serotype of PPR virus, but four distinct genetic lineages. Morbidity and mortality are high when occurring in naive sheep and goats populations. Cattle and African buffaloes (Syncerus caffer) are asymptomatically infected. Other wild ruminants and camels may express clinical signs and mortality. PPR has recently spread in southern and northern Africa, and in central and far-east Asia. More than one billion sheep and goats worldwide are at risk. PPR is also present in Europe through western Turkey. Because of its clinical incidence and the restrictions on animal movements, PPR is a disease of major economic importance. A live attenuated vaccine was developed in the 1980s, and has been widely used in sheep and goats. Current researches aim (i) to make it more thermotolerant for use in countries with limited cold chain, and (ii) to add a DIVA mark to shorten and reduce the cost of final eradication. Rinderpest virus-another Morbillivirus-was the first animal virus to be eradicated from Earth. PPRV has been proposed as the next candidate. Considering its wide distribution and its multiple target host species which have an intense mobility, it will be a long process that cannot exclusively rely on mass vaccination. PPR specific epidemiological features and socio-economic considerations will also have to be taken into account, and sustained international, coordinated, and funded strategy based on a regional approach of PPR control will be the guarantee toward success.

Quantitative one-step real-time RT-PCR for the fast detection of the four genotypes of PPRV

A one-step real-time Taqman RT-PCR assay (RRT-PCR) for peste des petits ruminants virus (PPRV) was developed to detect the four lineages of PPRV by targeting the nucleoprotein (N) gene of the virus. This new assay was compared to a conventional RT-PCR on reference strains and field materials. Quantitation was performed against a standard based on a synthetic transcript of the NPPR gene for which a minimum of 32 copies per reaction were detected with a corresponding C(t) value of 39. Depending on the lineage involved, the detection limit of RRT-PCR was decreased by one to three log copies relative to the conventional method. The lower stringency occurred with lineage III because of minor nucleotide mismatches within the probe region. The assay did not detect phylogenetically or symptomatically related viruses of ruminants (such as rinderpest, bluetongue, and bovine viral diarrhea viruses). However, it was capable of detecting 20% more positive field samples with low viral RNA loads compared to the conventional PCR method. When compared on a proficiency panel to the method developed by Bao et al. (2008), the sensitivity of the in-house assay was slightly improved on lineage II. It proved significantly faster to perform and hence better adapted for monitoring large numbers of at risk or diseased animals.

First serological investigation of peste-des-petits-ruminants and Rift Valley fever in Tunisia.

This study, carried out between September 2006 and January 2007, is the first cross-sectional serological investigation of peste-des-petits-ruminants (PPR) and Rift Valley fever (RVF) in Tunisia. The objective was to assess the potential need to develop a dual, recombinant PPR-RVF vaccine and how such a vaccine might be utilised in Tunisia. An overall PPR seroprevalence of 7.45% was determined, a finding supported by the high specificity (99.4%) and sensitivity (94.5%) of the ELISA used. On assessment of the diversity and density of mosquitoes in the sampling area, four species of RVF-vectors of the genus Aedes and Culex were identified. However, no serological evidence of RVF was found despite the use of a highly sensitive ELISA (99-100%). Larger scale investigations are underway to confirm these findings and the continuation of the emergency vaccination program against these two diseases remains valid.

Resurgence of Morbillivirus infection in Mediterranean dolphins off the French coast

IN the past 20 years, epizootics of Morbillivirus infection have occurred among several marine mammal populations worldwide ([Van Bressem and others 2001][1]). From 1990 to 1992, dolphin Morbillivirus spread to the striped dolphin ( Stenella coeruleoalba ) population of the Mediterranean sea,

Protective efficacy of a single immunization with capripoxvirus-vectored recombinant peste des petits ruminants vaccines in presence of pre-existing immunity

Sheeppox, goatpox and peste des petits ruminants (PPR) are highly contagious ruminant diseases widely distributed in Africa, the Middle East and Asia. Capripoxvirus (CPV)-vectored recombinant PPR vaccines (rCPV-PPR vaccines), which have been developed and shown to protect against both Capripox (CP) and PPR, would be critical tools in the control of these important diseases. In most parts of the world, these disease distributions overlap each other leaving concerns about the potential impact that pre-existing immunity against either disease may have on the protective efficacy of these bivalent rCPV-PPR vaccines. Currently, this question has not been indisputably addressed. Therefore, we undertook this study, under experimental conditions designed for the context of mass vaccination campaigns of small ruminants, using the two CPV recombinants (Kenya sheep-1 (KS-1) strain-based constructs) developed previously in our laboratory. Pre-existing immunity was first induced by immunization either with an attenuated CPV vaccine strain (KS-1) or the attenuated PPRV vaccine strain (Nigeria 75/1) and animals were thereafter inoculated once subcutaneously with a mixture of CPV recombinants expressing either the hemagglutinin (H) or the fusion (F) protein gene of PPRV (10(3) TCID50/animal of each). Finally, these animals were challenged with a virulent CPV strain followed by a virulent PPRV strain 3 weeks later. Our study demonstrated full protection against CP for vaccinated animals with prior exposure to PPRV and a partial protection against PPR for vaccinated animals with prior exposure to CPV. The latter animals exhibited a mild clinical form of PPR and did not show any post-challenge anamnestic neutralizing antibody response against PPRV. The implications of these results are discussed herein and suggestions made for future research regarding the development of CPV-vectored vaccines.

The incursion, persistence and spread of peste des petits ruminants in Tanzania: Epidemiological patterns and predictions

Peste des petits ruminants virus, which causes a severe disease in sheep and goats, has only recently been officially declared to be present in Tanzania. An epidemiological study was carried out between September 2008 and October 2010 to investigate the incursion, persistence and spread of the virus in Tanzania. The investigation involved serosurveillance, outbreak investigation and computation of epidemiological indices such as the effective reproductive number, persistence and the threshold level for vaccination. Field and molecular epidemiological techniques were applied to isolate, characterise and trace the origin of the virus in Tanzania. A total of 2182 serum samples from goats and 1296 from sheep from 79 villages across 12 districts were investigated. Village-level prevalence of infection was variable (0.00% – 88.00%) and was higher in pastoral than in agro-pastoral villages. The overall antibody response to the virus was 22.10% (CI95% = 20.72% – 23.48%). About 68.00% and 73.00% of seropositive goats and sheep, respectively, did not show clinical signs. The proportion of seropositive animals differed significantly (p ≤ 0.001) between age groups, sex and farming practices. Real-time polymerase chain reaction results showed that the isolated strains belong to lineage III, whose origin is in East Africa and the Middle East. This indicates that one of the northern neighbouring countries is most likely the source of infection. The computed overall effective reproductive number, the threshold level of vaccination necessary to eradicate the disease and persistence were 4.75% and 98.00%, respectively. These estimates indicate that achieving elimination of the peste des petits ruminants virus from pastoral flocks will require significant effort and development of highly effective intervention tools.

RNA Interference against Animal Viruses: How Morbilliviruses Generate Extended Diversity To Escape Small Interfering RNA Control

ABSTRACT Viruses are serious threats to human and animal health. Vaccines can prevent viral diseases, but few antiviral treatments are available to control evolving infections. Among new antiviral therapies, RNA interference (RNAi) has been the focus of intensive research. However, along with the development of efficient RNAi-based therapeutics comes the risk of emergence of resistant viruses. In this study, we challenged the in vitro propensity of a morbillivirus (peste des petits ruminants virus), a stable RNA virus, to escape the inhibition conferred by single or multiple small interfering RNAs (siRNAs) against conserved regions of the N gene. Except with the combination of three different siRNAs, the virus systematically escaped RNAi after 3 to 20 consecutive passages. The genetic modifications involved consisted of single or multiple point nucleotide mutations and a deletion of a stretch of six nucleotides, illustrating that this virus has an unusual genomic malleability.

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.