Patricia Gil

Newcastle disease virus in Madagascar: identification of an original genotype possibly deriving from a died out ancestor of genotype IV.

In Madagascar, Newcastle disease (ND) has become enzootic after the first documented epizootics in 1946, with recurrent annual outbreaks causing mortality up to 40%. Four ND viruses recently isolated in Madagascar were genotypically and pathotypically characterised. By phylogenetic inference based on the F and HN genes, and also full-genome sequence analyses, the NDV Malagasy isolates form a cluster distant enough to constitute a new genotype hereby proposed as genotype XI. This new genotype is presumably deriving from an ancestor close to genotype IV introduced in the island probably more than 50 years ago. Our data show also that all the previously described neutralising epitopes are conserved between Malagasy and vaccine strains. However, the potential implication in vaccination failures of specific amino acid substitutions predominantly found on surface-exposed epitopes of F and HN proteins is discussed.

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.

Vaccination with Trypanosoma rangeli reduces the infectiousness of dogs experimentally infected with Trypanosoma cruzi.

Abstract The goal of this work was to test the efficacy of the vaccination with Trypanosoma rangeli in dogs. Mongrel dogs received three subcutaneous injections of fixed T. rangeli epimastigotes at 6-week intervals. Such immunisation induced antibodies against Trypanosoma cruzi. While both control and immunised dogs developed detectable parasitemia, this was lower and shorter in vaccinated animals. Interestingly, feeding of Triatoma infestans nymphs on vaccinated and chronically infected dogs led to a sharp reduction in the rate of bug infection. These results suggest that it might be possible to reduce the vectorial parasitemia through vaccination of dogs. As dogs are known to play a major role in the domestic cycle of T. cruzi, this might represent a strategy to reduce parasite transmission to humans.

Investigating Avian Influenza Infection Hotspots in Old-World Shorebirds

Heterogeneity in the transmission rates of pathogens across hosts or environments may produce disease hotspots, which are defined as specific sites, times or species associations in which the infection rate is consistently elevated. Hotspots for avian influenza virus (AIV) in wild birds are largely unstudied and poorly understood. A striking feature is the existence of a unique but consistent AIV hotspot in shorebirds (Charadriiformes) associated with a single species at a specific location and time (ruddy turnstone Arenaria interpres at Delaware Bay, USA, in May). This unique case, though a valuable reference, limits our capacity to explore and understand the general properties of AIV hotspots in shorebirds. Unfortunately, relatively few shorebirds have been sampled outside Delaware Bay and they belong to only a few shorebird families; there also has been a lack of consistent oropharyngeal sampling as a complement to cloacal sampling. In this study we looked for AIV hotspots associated with other shorebird species and/or with some of the larger congregation sites of shorebirds in the old world. We assembled and analysed a regionally extensive dataset of AIV prevalence from 69 shorebird species sampled in 25 countries across Africa and Western Eurasia. Despite this diverse and extensive coverage we did not detect any new shorebird AIV hotspots. Neither large shorebird congregation sites nor the ruddy turnstone were consistently associated with AIV hotspots. We did, however, find a low but widespread circulation of AIV in shorebirds that contrast with the absence of AIV previously reported in shorebirds in Europe. A very high AIV antibody prevalence coupled to a low infection rate was found in both first-year and adult birds of two migratory sandpiper species, suggesting the potential existence of an AIV hotspot along their migratory flyway that is yet to be discovered.

Plasminogen Controls Inflammation and Pathogenesis of Influenza Virus Infections via Fibrinolysis

Detrimental inflammation of the lungs is a hallmark of severe influenza virus infections. Endothelial cells are the source of cytokine amplification, although mechanisms underlying this process are unknown. Here, using combined pharmacological and gene-deletion approaches, we show that plasminogen controls lung inflammation and pathogenesis of infections with influenza A/PR/8/34, highly pathogenic H5N1 and 2009 pandemic H1N1 viruses. Reduction of virus replication was not responsible for the observed effect. However, pharmacological depletion of fibrinogen, the main target of plasminogen reversed disease resistance of plasminogen-deficient mice or mice treated with an inhibitor of plasminogen-mediated fibrinolysis. Therefore, plasminogen contributes to the deleterious inflammation of the lungs and local fibrin clot formation may be implicated in host defense against influenza virus infections. Our studies suggest that the hemostatic system might be explored for novel treatments against influenza.

New avian paramyxoviruses Type I strains identified in Africa provide new outcomes for phylogeny reconstruction and genotype classification

Newcastle disease (ND) is one of the most lethal diseases of poultry worldwide. It is caused by an avian paramyxovirus 1 that has high genomic diversity. In the framework of an international surveillance program launched in 2007, several thousand samples from domestic and wild birds in Africa were collected and analyzed. ND viruses (NDV) were detected and isolated in apparently healthy fowls and wild birds. However, two thirds of the isolates collected in this study were classified as virulent strains of NDV based on the molecular analysis of the fusion protein and experimental in vivo challenges with two representative isolates. Phylogenetic analysis based on the F and HN genes showed that isolates recovered from poultry in Mali and Ethiopia form new groups, herein proposed as genotypes XIV and sub-genotype VIf with reference to the new nomenclature described by Diel’s group. In Madagascar, the circulation of NDV strains of genotype XI, originally reported elsewhere, is also confirmed. Full genome sequencing of five African isolates was generated and an extensive phylogeny reconstruction was carried out based on the nucleotide sequences. The evolutionary distances between groups and the specific amino acid signatures of each cluster allowed us to refine the genotype nomenclature.

Circulation of avian influenza viruses in wild birds in Inner Niger Delta, Mali

Please cite this paper as: Cappelle et al. (2012) Circulation of avian influenza viruses in wild birds in Inner Niger Delta, Mali. Influenza and Other Respiratory Viruses 6(4), 240–244.

Avian influenza in backyard poultry of the Mopti region, Mali.

This study reports the first evidence of circulation of avian influenza viruses (AIV) in domestic poultry in Mali. In the Mopti region, where AIV have already been isolated in migratory water birds, we sampled 223 backyard domestic birds potentially in contact with wild birds and found that 3.6% had tracheal or cloacal swabs positive by real-time reverse transcription PCR (rRT-PCR) for type A influenza viruses (IVA) and that 13.7% had sera positive by commercial ELISA test detecting antibodies against IVA. None of the birds positive by rRT-PCR for IVA was positive by rRT-PCR for H5 and H7 subtypes, and none showed any clinical signs therefore indicating the circulation of low pathogenic avian influenza. Unfortunately, no virus isolation was possible. Further studies are needed to assess the temporal evolution of AIV circulation in the Mopti region and its possible correlation with the presence of wild birds.

Two-Plasmid system to increase the rescue efficiency of #Paramyxoviruses# by reverse genetics: the example of rescuing newcastle disease Virus

Within paramyxoviruses, conventional reverse genetics require the transfection of a minimum of four plasmids: three to reconstruct the viral polymerase complex that replicates and expresses the virus genome delivered by a fourth plasmid. The successful transfection of four or more plasmids of different sizes into one cell and the subsequent generation of at least one viable and replicable viral particle is a rare event, which explains the low rescue efficiency, especially of low virulent viruses with reduced replication efficiency in cell lines. In this study, we report on an improved reverse genetics system developed for an avian paramyxovirus, Newcastle Disease Virus (NDV), in which the number of plasmids was reduced from four to two. Compared to the conventional method, the 2-plasmid system enables earlier and increased production of rescued viruses and, in addition, makes it possible to rescue viruses that it was not possible to rescue using the 4-plasmid system.

Diverse gammacoronaviruses detected in wild birds from Madagascar

To date, infectious bronchitis virus (IBV) is potentially found in wild birds of different species. This work reports the survey of coronaviruses in wild birds from Madagascar based on the targeting of a conserved genome sequence among different groups of CoVs. Phylogenetic analyses revealed the presence of gammacoronaviruses in different species of Gruiformes, Passeriformes, Ciconiiformes, Anseriformes, and Charadriiformes. Furthermore, some sequences were related to various IBV strains. Aquatic and migratory birds may play an important role in the maintenance and spread of coronaviruses in nature, highlighting their possible contribution in the emergence of new coronavirus diseases in wild and domestic birds.