Phenotypic and Genetic Evolutions of a Porcine Reproductive and Respiratory Syndrome Modified Live Vaccine after Limited Passages in Pigs

Modified live vaccines (MLVs) against the porcine reproductive and respiratory syndrome virus (PRRSV) have been regularly associated with safety issues, such as reversion to virulence. In order to characterize the phenotypic and genetic evolution of the PRRSV-1 DV strain from the Porcilis® PRRS MLV after limited passages in pigs, three in vivo experiments were performed. Trial#1 aimed (i) at studying transmission of the vaccine strain from vaccinated to unvaccinated contact pigs. Trial#2 and Trial#3 were designed (ii) to assess the reproducibility of Trial#1, using another vaccine batch, and (iii) to compare the virulence levels of two DV strains isolated from vaccinated (passage one) and diseased contact pigs (passage two) from Trial#1. DV strain isolates from vaccinated and contact pigs from Trial#1 and Trial#2 were submitted to Next-Generation Sequencing (NGS) full-genome sequencing. All contact animals from Trial#1 were infected and showed significantly increased viremia compared to vaccinated pigs, whereas no such change was observed during Trial#2. In Trial#3, viremia and transmission were higher for inoculated pigs with passage two of the DV strain, compared with passage one. In this study, we showed that the re-adaptation of the DV strain to pigs is associated with faster replication and increased transmission of the vaccine strain. Punctually, a decrease of attenuation of the DV vaccine strain associated with clinical signs and increased viremia may occur after limited passages in pigs. Furthermore, we identified three mutations linked to pig re-adaptation and five other mutations as potential virulence determinants

Promising new vaccine candidates against Campylobacter in broilers.

Campylobacter is the leading cause of human bacterial gastroenteritis in the European Union. Birds represent the main reservoir of the bacteria, and human campylobacteriosis mainly occurs after consuming and/or handling poultry meat. Reducing avian intestinal Campylobacter loads should impact the incidence of human diseases. At the primary production level, several measures have been identified to reach this goal, including vaccination of poultry. Despite many studies, however, no efficient vaccine is currently available. We have recently identified new vaccine candidates using the reverse vaccinology strategy. This study assessed the in vivo immune and protective potential of six newly-identified vaccine antigens. Among the candidates tested on Ross broiler chickens, four (YP_001000437.1, YP_001000562.1, YP_999817.1, and YP_999838.1) significantly reduced cecal Campylobacter loads by between 2 and 4.2 log10 CFU/g, with the concomitant development of a specific humoral immune response. In a second trial, cecal load reductions results were not statistically confirmed despite the induction of a strong immune response. These vaccine candidates need to be further investigated since they present promising features

Bidirectional Human–Swine Transmission of Seasonal Influenza A(H1N1)pdm09 Virus in Pig Herd, France, 2018

International audienceIn 2018, a veterinarian became sick shortly after swabbing sows exhibiting respiratory syndrome on a farm in France. Epidemiologic data and genetic analyses revealed consecutive human-to-swine and swine-to-human influenza A(H1N1)pdm09 virus transmission, which occurred despite some biosecurity measures. Providing pig industry workers the annual influenza vaccine might reduce transmission risk

Promising new vaccine candidates against <i>Campylobacter</i> in broilers

<div><p><i>Campylobacter</i> is the leading cause of human bacterial gastroenteritis in the European Union. Birds represent the main reservoir of the bacteria, and human campylobacteriosis mainly occurs after consuming and/or handling poultry meat. Reducing avian intestinal <i>Campylobacter</i> loads should impact the incidence of human diseases. At the primary production level, several measures have been identified to reach this goal, including vaccination of poultry. Despite many studies, however, no efficient vaccine is currently available. We have recently identified new vaccine candidates using the reverse vaccinology strategy. This study assessed the <i>in vivo</i> immune and protective potential of six newly-identified vaccine antigens. Among the candidates tested on Ross broiler chickens, four (YP_001000437.1, YP_001000562.1, YP_999817.1, and YP_999838.1) significantly reduced cecal <i>Campylobacter</i> loads by between 2 and 4.2 log₁₀ CFU/g, with the concomitant development of a specific humoral immune response. In a second trial, cecal load reductions results were not statistically confirmed despite the induction of a strong immune response. These vaccine candidates need to be further investigated since they present promising features.</p></div

Investigations into SARS-CoV-2 and other coronaviruses on mink farms in France late in the first year of the COVID-19 pandemic.

Soon after the beginning of the COVID-19 pandemic in early 2020, the Betacoronavirus SARS-CoV-2 infection of several mink farms breeding American minks (Neovison vison) for fur was detected in various European countries. The risk of a new reservoir being formed and of a reverse zoonosis from minks quickly became a major concern. The aim of this study was to investigate the four French mink farms to see whether SARS-CoV-2 was circulating there in late 2020. The investigations took place during the slaughtering period, thus facilitating different types of sampling (swabs and blood). On one of the four mink farms, 96.6% of serum samples were positive when tested with a SARS-CoV-2 ELISA coated with purified N protein recombinant antigen, and 54 out of 162 (33%) pharyngo-tracheal swabs were positive by RT-qPCR. The genetic variability among 12 SARS-CoV-2 genomes sequenced from this farm indicated the co-circulation of several lineages at the time of sampling. All the SARS-CoV-2 genomes detected were nested within the 20A clade (Nextclade), together with SARS-CoV-2 genomes from humans sampled during the same period. The percentage of SARS-CoV-2 seropositivity by ELISA varied between 0.3 and 1.1% on the other three farms. Interestingly, among these three farms, 11 pharyngo-tracheal swabs and 3 fecal pools from two farms were positive by end-point RT-PCR for an Alphacoronavirus very similar to a mink coronavirus sequence observed on Danish farms in 2015. In addition, a mink Caliciviridae was identified on one of the two farms positive for Alphacoronavirus. The clinical impact of these inapparent viral infections is not known. The co-infection of SARS-CoV-2 with other viruses on mink farms could help explain the diversity of clinical symptoms noted on different infected farms in Europe. In addition, the co-circulation of an Alphacoronavirus and SARS-CoV-2 on a mink farm would potentially increase the risk of viral recombination between alpha and betacoronaviruses as already suggested in wild and domestic animals, as well as in humans

Anti-<i>Campylobacter</i> IgY antibodies in the sera of chickens after vaccination and challenge.

<p>The chicks were immunized by the IM route, on day 5 with DNA and on day 12 with proteins. They were then orally infected on day 19 by <i>Campylobacter</i>. The specific systemic immune response was assessed weekly from blood samples until the end of the experiment on day 42 ± 1 day (data from day 1 to day 14 not shown) by ELISAs which reveal the IgY antibodies (OD 490nm) (A) YP562, YP1115, YP9769, YP437, YP9817, and YP9838 antigens were individually injected in the first experiment along with a combination of antigens (Pool) and compared to a DNA/protein control group (injected with adjuvants only). (B) Four antigens (YP562, YP437, YP9817, and YP9838) were tested again in a second experiment and compared to a DNA/protein control group (injected with adjuvants only). The negative control group was administered with PBS only. Each dot corresponds to the OD of an individual chicken. Bars represent the medians for each group. *: statistically significant differences from the control group at the same time point (p < 0.05).</p

Investigations on SARS-CoV-2 and other coronaviruses in mink farms in France at the end of the first year of COVID-19 pandemic

Posted February 02, 2023 on bioRxiv.Soon after the beginning of the COVID-19 pandemic in early 2020, the Betacoronavirus SARS-CoV-2 infection of several mink farms breeding American minks ( Neovison vison ) for fur was detected in several countries of Europe. The risk of a new reservoir formation and of a reverse zoonosis from minks was then a major concern. The aim of this study was to investigate the four French mink farms for the circulation of SARS-CoV-2 at the end of 2020. The investigations took place during the slaughtering period thus facilitating different types of sampling (swabs and blood). In one of the four mink farms, 96.6% of serum samples were positive in SARS-CoV-2 ELISA coated with purified N protein recombinant antigen and 54 out of 162 (33%) pharyngo-tracheal swabs were positive by RT-qPCR. The genetic variability among 12 SARS-CoV-2 genomes sequenced in this farm indicated the co-circulation of several lineages at the time of sampling. All SARS-CoV-2 genomes detected were nested within the 20A clade (Nextclade), together with SARS-CoV-2 genomes from humans sampled at the same period. The percentage of SARS-CoV-2 seropositivity by ELISA varied between 0.5 and 1.2% in the three other farms. Interestingly, among these three farms, 11 pharyngo-tracheal swabs and 3 fecal pools from two farms were positive by end-point RT-PCR for an Alphacoronavirus highly similar to a mink coronavirus sequence observed in Danish farms in 2015. In addition, a mink Caliciviridae was identified in one of the two positive farms for Alphacoronavirus . The clinical impact of these unapparent viral infections is not known. The co-infection of SARS-CoV-2 with other viruses in mink farms could contribute to explain the diversity of clinical symptoms noted in different infected farms in Europe. In addition, the co-circulation of an Alphacoronavirus and SARS-CoV-2 within a mink farm would increase potentially the risk of viral recombination between alpha and betacoronaviruses already suggested in wild and domestic animals, as well as in humans. Author summary France is not a country of major mink fur production. Following the SARS-CoV-2 contamination of mink farms in Denmark and the Netherlands, the question arose for the four French farms. The investigation conducted at the same time in the four farms revealed the contamination of one of them by a variant different from the one circulating at the same time in Denmark and the Netherlands mink farms. Investigation of three other farms free of SARS-CoV-2 contamination revealed the circulation of other viruses including a mink Alphacoronavirus and Caliciviridae , which could modify the symptomatology of SARS-CoV-2 infection in minks

<i>Campylobacter</i> loads in chicken ceca after vaccination and challenge.

<p>After two vaccinations on days 5 and 12, chickens were then orally infected on day 19. <i>Campylobacter</i> counts were evaluated at the end of the experiment from ceca samples. (A) YP562, YP1115, YP9769, YP437, YP9817, and YP9838 antigens were individually injected in the first experiment along with a combination of antigens (Pool) and compared to a DNA/protein control group (injected with adjuvants only). Ceca samples were cultured on mCCDA for <i>Campylobacter</i> counts (Log CFU/g). Groups without common letters (a-c) differed significantly (p < 0.05). (B) Four antigens (YP562, YP437, YP9817, and YP9838) were tested again in a second experiment and compared to DNA/protein control group (injected with adjuvant only) and negative control group administered with PBS only. Quantitative PCR on ceca samples was used for <i>Campylobacter</i> counts (Log GenEq/g). The detection limit was determined to lie at 1.88 log₁₀ GenEq/g. Samples with counts under the threshold were set at 0.94 log₁₀ GenEq/g. No significant differences were observed between groups.</p

Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4b Virus in Domestic Cat, France, 2022

We detected highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus in a domestic cat that lived near a duck farm infected by a closely related virus in France during December 2022. Enhanced surveillance of symptomatic domestic carnivores in contact with infected birds is recommended to prevent further spread to mammals and humans

Anti-<i>Campylobacter</i> IgY antibodies in sera and <i>Campylobacter</i> loads in chicken ceca after DNA vaccination alone or protein vaccination alone and challenged using the YP9817 antigen.

<p>Birds were vaccinated with the DNA vaccine alone on day 5 or with proteins alone on day 12 and then infected on day 19. (A) The IgY levels in blood samples were assessed by ELISAs each week until the end of the experiment on day 42 ± 1 day (data from day 1 to day 14 not shown). Each dot corresponds to the OD of an individual chicken. Bars represent the medians for each group. (B) <i>Campylobacter</i> counts were evaluated at the end of the experiment from ceca samples by qPCR (Log GenEq/g). The detection limit was set at 1.88 log₁₀ GenEq/g. Samples with counts under the threshold were set at 0.94 log₁₀ GenEq/g. No significant differences were observed between groups.</p