7-day post-vaccination efficacy of the CSF CL strain produced on ovine cell line against a virulent classical swine fever (Hog cholera) challenge

Classical swine fever (CSF), also known as hog cholera, is a highly contagious viral disease classified as a notifiable (previously List A) pig disease by OIE. In an infected environment, vaccines are the basic tools for control and eradication of CSFV. This study aimed at assessing the efficacy of an attenuated CSF CL strain produced on ovine cells against a virulent CSF challenge performed 7 days post-vaccination. Material and methodsTwo groups of 8 CSF-negative crossbred pigs weighing 18 kg were either vaccinated with a live one dose of CL strain (>100 PD50/dose) or left unvaccinated. Seven days post-vaccination, they were challenged with 5.5log10TCID50 CSFV of Haiti-96 strain both intramuscularly and intranasally with separated aliquots. Clinical signs, rectal temperature were monitored for 28 days post-challenge (DPC) and necropsied. Blood samples, nasal swabs and tonsil scrapings were regularly collected and assayed for blood formulation, sera antibody titres (E2-Erms ELISAs, SN titrations), and viral loads in total blood, nasal and tonsil mucus. ResultsAll controls showed typical acute CSF justifying euthanasia on ethical ground 22 DPCH at the latest. They also developed severe leukopenia and lymphopenia. Necropsic lesions were evocative of chronic form of CSF. None of the vaccinates developed any sign of CSF.CSFV was detected in controls from 4DPC in blood plateauing close to 6log10TCID50/mL. CSFV was detected in nasal and tonsillar mucus from 8DPC reaching up to 4.8log10TCID50/mL. Vaccinates showed no detectable CSFV in any sample post-challenge.All pigs were antibody negative before challenge. A seroneutralizing anamestic reaction was evidenced as early as 7DPC in all vaccinates whereas ELISA antibody titres turned positive slower. Serological response to challenge was almost absent in controls. Discussion and conclusionViral circulation in herds relies mainly on direct nose-to-nose contacts and in-utero transmission. The ability of vaccines to limit CSFV transmission is vital for control and eradication strategies. Under the conditions of the study, the CL strain was able to totally prevent CSF and totally abolished both CSFV viremia and mucosal shedding as early as 7 days post-vaccination, thus showing its relevance for whole herd strategies. Additionally, it was noticed that ELISA correlated poorly with protection.Fil: Risatti, Guillermo R.. University of Connecticut; Estados UnidosFil: Perez, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina25th International Pig Veterinary Society CongressChongqingChinaInternational Pig Veterinary Societ

Three-week post-vaccination efficacy of the CSF CL strain produced on ovine cell line against a virulent classical swine fever (Hog cholera)

Classical swine fever (CSF) is a highly contagious viral disease classified as a notifiable pig disease by OIE. In an infected environment, vaccines are the basic tools for control and eradication of CSFV. This study aimed at assessing the efficacy of an attenuated CSF CL strain produced on ovine cells against a virulent CSF challenge performed three weeks post-vaccination. Material and methodsTwo groups of 8 CSF-negative crossbred pigs weighing 18 kg were either vaccinated with a live one dose of CL strain (>100 PD50/dose) or left unvaccinated. Three weeks post-vaccination, they were challenged with 5.5log10TCID50 CSFV of Haiti-96 strain both intramuscularly and intranasally with separated aliquots. Clinical signs, rectal temperature were monitored for 28 days post-challenge (DPC) and necropsied. Blood samples, nasal swabs and tonsil scrapings were regularly collected and assayed for blood formulation, sera antibody titres (E2-Erms ELISAs, SN titrations), and viral loads in total blood, nasal and tonsil mucus. ResultsFollowing 5-6 incubation days, all controls showed typical acute CSF. Two of them were euthanized on ethical ground. They also developed severe leukopenia and lymphopenia. Necropsic lesions were evocative of chronic form of CSF. None of the vaccinates developed any sign of CSF.In controls, CSFV viremia was detected from 5DPC reaching levels above 6log10TCID50/mL from 6DPCH to 11DPCH. Tonsils were positive for CSF as well from 5DPCH and viral sheddind in nasal mucus could reach more than 4log10TCID50/mL. Vaccinates showed drastically (p<0.001) reduced viremia with overall mean titer of 1.7log10TCID50/mL and no detectable CSFV in tonsils or nasal mucus. Vaccinates showed low levels of seroneutralizing antibodies and neither E2 nor Erms antibiodies before challenge. Following challenge seroconversion was significantly (p<0.05) faster in vaccinates. Discussion and conclusionViral circulation in herds relies mainly on direct nose-to-nose contacts and in-utero transmission. The ability of vaccines to limit CSFV transmission is vital for control and eradication strategies. Under the conditions of the study, the CL strain was able to totally prevent CSF, drastically limit viremia and abolished CSFV shedding through oro-nasal route.Total protection despite absent to low antibody levels suggested a major contribution of cell-mediated immunity to protection.Fil: Risatti, Guillermo R.. University of Connecticut; Estados UnidosFil: Perez, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina25th International Pig Veterinary Society CongressChongqingChinaInternational Pig Veterinary Society Congres

Classical Swine Fever Virus p7 Protein Interacts with Host Protein CAMLG and Regulates Calcium Permeability at the Endoplasmic Reticulum

We have previously shown that Classical Swine Fever Virus (CSFV) p7 is an essential nonstructural protein with a viroporin activity, a critical function in the progression of virus infection. We also identified p7 domains and amino acid residues critical for pore formation. Here, we describe how p7 specifically interacts with host protein CAMLG, an integral ER transmembrane protein involved in intracellular calcium release regulation and signal response generation. Detection of interaction as well as the identification of p7 areas mediating interaction with CAMLG was performed by yeast two-hybrid. p7-CAMLG interaction was further confirmed by confocal microscopy in eukaryotic cells, co-expressing both proteins. Mutant forms of p7 having substituted native residues identified as mediating interaction with CAMLG showed a decreased co-localization compared with the native forms of p7. Furthermore, it is shown that native p7, but not the mutated forms of p7 that fail to interact with CAMLG, efficiently mediates calcium permeability in the ER. Interestingly, viruses harboring some of those mutated forms of p7 have been previously shown to have a significantly decreased virulence in swine.ARS/USDA-University of Connecticut SCA# 58-1940-1-190 and ARS/USDA-University of the Basque Country NACA#8064-32000-056-18S

Genomic Features of Salmonella enterica Subspecies houtenae Serotype 45:g,z51:- Isolated from Multiple Abdominal Abscesses of an African Fat-Tailed Gecko, United States, 2020

Salmonella enterica subsp. houtenae (S. houtenae) is a common subspecies in reptiles and has been implicated as a source of serious and life-threatening diseases in humans. Although occurrence and significance of S. houtenae infections have been extensively studied, the genetic features of S. houtenae have remained unknown due to a lack of available high-quality genome sequences. We obtained the complete genome sequence of S. houtenae 45:g,z51:- strain 20-369 isolated from multiple abdominal abscesses of an African fat-tailed gecko (Hemitheconyx caudicinctus) using Nanopore and Illumina sequencing technologies and generated the 4.65Mbp complete genome sequence of the S. houtenae str. 20-369. We annotated and analyzed the genome sequence with the aim to gain a deeper understanding of the genome characteristics associated with its pathogenicity. Overall, this study found several interesting genomic features such as pseudogene formation, virulence gene profile, and novel genomic islands. This study provides basis for an understanding possible genetic mechanism underlying pathogenicity of S. houtenae 45:g,z51:- as well as a high-quality genome reference for future comparison studies

Complete mitochondrial genome of Asian longhorned tick, Haemaphysalis longicornis, Neumann, 1901 (Acari: Ixodida: Ixodidae) identified in the United States

Haemaphysalis longicornis (Ixodida: Ixodidae), the Asian longhorned tick, which is native to temperate East Asia, has been recently detected in the northeastern region of the United States, drawing concerns about its potential impact on the US animal and public health sectors. Knowledge about the genetic features of H. longicornis found in the US is limited. Therefore, we sequenced the complete mitochondrial genome (mt-genome) from two H. longicornis ticks recently collected in the State of New York, USA, in 2020. These ticks were morphologically identified and tested for tick-borne pathogens at the Connecticut Veterinary Medical Diagnostic Laboratory (Storrs, CT). The mt-genome was 14,694 bp in length and encoded 37 genes, including 13 protein-coding genes, 22 transfer RNAs, and two ribosomal RNAs. Phylogenetic analysis showed that the mt-genome clustered with those of other H. longicornis identified in China. The mt-genome sequence was 99.7% identical to a H. longicornis mt-genome (GenBank: MK439888) collected in China. The cox1 gene haplotype in these ticks belonged to the H1 type, which is the dominant haplotype present in central NJ and Staten Island, NY. The complete mt-genome data are needed to provide insights into genetic changes and phylogenetic studies of H. longicornis ticks

Whole Genome Sequencing and Phylogenetic Analysis of Rabies Viruses from Bats in Connecticut, USA, 2018&ndash;2019

We performed whole genome sequencing and genetic characterization of rabies viruses (RABV) detected in bats submitted to the Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) during 2018&ndash;2019. Among 88 bats submitted to CVMDL, six brain samples (6.8%, 95% confidence interval: 1.6% to 12.1%) tested positive by direct fluorescent antibody test. RABVs were detected in big brown bats (Eptesicus fuscus, n = 4), a hoary bat (Lasiurus cinereus, n = 1), and an unidentified bat species (n = 1). Complete coding sequences of four out of six detected RABVs were obtained. In phylogenetic analysis, the RABVs (18-62, 18-4347, and 19-2274) from big brown bats belong to the bats EF-E1 clade, clustering with RABVs detected from the same bat species in Pennsylvania and New Jersey. The bat RABV (19-2898) detected from the migratory hoary bat belongs to the bats LC clade, clustering with the eleven viruses detected from the same species in Arizona, Washington, Idaho, and Tennessee. The approach used in this study generated novel data regarding genetic relationships of RABV variants, including their reservoirs, and their spatial origin and it would be useful as reference data for future investigations on RABV in North America. Continued surveillance and genome sequencing of bat RABV would be needed to monitor virus evolution and transmission, and to assess the emergence of genetic mutations that may be relevant for public health

Early protection events in swine immunized with an experimental live attenuated classical swine fever marker vaccine, FlagT4G.

Prophylactic vaccination using live attenuated classical swine fever (CSF) vaccines has been a very effective method to control the disease in endemic regions and during outbreaks in previously disease-free areas. These vaccines confer effective protection against the disease at early times post-vaccination although the mechanisms mediating the protection are poorly characterized. Here we present the events occurring after the administration of our in-house developed live attenuated marker vaccine, FlagT4Gv. We previously reported that FlagT4Gv intramuscular (IM) administered conferred effective protection against intranasal challenge with virulent CSFV (BICv) as early as 7 days post-vaccination. Here we report that FlagT4Gv is able to induce protection against disease as early as three days post-vaccination. Immunohistochemical testing of tissues from FlagT4Gv-inoculated animals showed that tonsils were colonized by the vaccine virus by day 3 post-inoculation. There was a complete absence of BICv in tonsils of FlagT4Gv-inoculated animals which had been intranasal (IN) challenged with BICv 3 days after FlagT4Gv infection, confirming that FlagT4Gv inoculation confers sterile immunity. Analysis of systemic levels of 19 different cytokines in vaccinated animals demonstrated an increase of IFN-α three days after FlagT4Gv inoculation compared with mock infected controls

Image_1_Genome sequencing and analysis of the raccoon variant rabies lyssaviruses directly from clinical samples, Connecticut, 2017–2019.JPEG

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