An outbreak of classical swine fever in pigs in Bangladesh, 2015

Production of Bivalent Subunit Vaccine for Porcine via 2A-Like Sequence in Baculovirus Expression Vector System

Classical swine fever virus (CSFV) and porcine circovirus type 2 (PCV2) have caused severe diseases in swine populations worldwide. Here, a polycistronic baculovirus vector was developed to express a bivalent vaccine, consisting of the CSFV-E2 and PCV2-Cap protein, and an immunomodulator protein derived from the Flammulina velutipes, FVE-FIP, as well as the selection marker, green fluorescent protein. The simultaneous expression of the CSFV-E2 and PCV2-Cap protein was mediated by the 2A-like sequence derived from the Perina nuda virus (PnV), while the expression of the FVE-FIP was driven by the internal ribosome entry site (IRES) element derived from the Rhophalosipum padi virus (RhPV). The Western blot analysis result suggested that the CSFV-E2, PCV2-Cap, and FVE-FIP protein were successfully co-expressed by the infected Spodoptera frugiperda IPBL-Sf21 (Sf21) cell line. The extracted cell lysate containing all three recombinant proteins was administered to Balb/C mice with or without the supplementation of Freund’s adjuvant. The ELISA analysis of the serum collected from all the immunized groups showed detectable antibodies against CSFV-E2 and PCV2-Cap. Furthermore, the immunized group without the adjuvant supplementation demonstrated a similar level of antibodies to the group with adjuvant supplementation, suggesting the efficiency of the FVE-FIP in enhancing the immune response. These results demonstrated the polycistronic baculovirus vector could be employed to develop bivalent vaccines for pigs.

Pathology and molecular characterization of classical swine fever virus from piggery units in Haryana

Classical swine fever (CSF) is a highly contagious viral disease of pigs and is responsible for significant economic losses due to high morbidity and mortality. Pigs from nine different piggery units in Haryana were investigated for CSF suspected outbreaks during July 2017-June 2019. On the basis of clinical signs, pathology, reverse transcriptase polymerase chain reaction (RT-PCR) and sequencing, the disease in all piggery units was confirmed as CSF. The overall morbidity rate, cumulative mortality and case fatality rate (CFR) due to CSF in these units were 14.3, 9.3% and 65.5%, respectively. Age-wise statistical analysis identified no significant difference in morbidities and mortalities among three age groups, i.e. adult, young and piglets. However, there was a significant difference in CFR with highest among piglets (79.3%) followed by young (68.9%) and adults (45.1%). Seasonal analysis revealed highest cumulative mortality and CFR in winter (29.9% and 91.1%, respectively) followed by rainy season (24.3% and 69.9%, respectively). The findings of the present study are of significant veterinary importance to check the dissemination of CSFV by prompt diagnosis which would help in imposing control measures for minimizing the losses suffered by the piggery units of Haryana, India.

Motivation-based segmentation of game meat consumers: A look at the beliefs of food consumers during the COVID-19 crisis in China

Objectives

This research aims to explore the factors motivate consumers to eat game meat during a multi‐state disease outbreak.

Methods

It proposes a segmentation of consumers based on their attitudes toward and reveals the consumers' food beliefs that motivate their actions. Three segments of game meat consumers were identified: identity seekers, health seekers, and taste seekers.

Results

A survey of the potential impact that the COVID‐19 crisis has on these three clusters' future food choices showed that the identity and health seekers are more open to a change in food choices. However, the taste seekers are less likely to be influenced by external factors.

Conclusions

This research indicates that for the policymakers, the key is to take game meat consumers as an effective intervention entry point. It is crucial to facilitate healthy food choices and to promote socially‐ and culturally‐appropriate food beliefs by improving public awareness of the risks of game meat, and invest in organic food.

Research Implications

This research provides new insights into the food beliefs of game meat consumers via motivation‐based segmentation.

This research aims to explore the factors that motivated consumers to eat game meat during a multi‐state disease outbreak that was related to the practice of game consumption.

Simultaneous detection of classical swine fever virus and porcine circovirus 3 by SYBR green I-based duplex real-time fluorescence quantitative PCR

In the present study, the SYBR green I-based duplex quantitative polymerase chain reaction (qPCR) was developed for simultaneous detection of classical swine fever virus (CSFV) and porcine circovirus 3 (PCV3). The assay was used to detect both CSFV and PCV3 in one sample by their distinct melting temperatures (melting peaks at 87°C for CSFV and 81.5 °C for PCV3), and no specific fluorescence signals were detected for other non-targeted porcine pathogens. The assay had a high degree of linearity (R² > 0.998) with the detection limits of 23 copies/μL for CSFV and 36 copies/μL for PCV3, and exhibited high repeatability and reproducibility with a low coefficient of variation below 2.0% in both intra- and inter-assay. In this study, 130 clinical samples collected from sick pigs in the field were tested by this assay with the positive rates of 9.23% (12/130) for CSFV and 21.54% (28/130) for PCV3 respectively, and the positive rate of CSFV and PCV3 co-infection was 6.92% (9/130). Our results showed that the developed method was a reliable diagnostic tool to monitor and survey CSFV, PCV3 and CSFV/PCV3 co-infection in the field.

Commercial E2 subunit vaccine provides full protection to pigs against lethal challenge with 4 strains of classical swine fever virus genotype 2

Classical swine fever (CSF) still threatens the swine industry in China, with genotype 2 isolates of CSFV dominating the epizootics. In 2018 the first E2 subunit marker vaccine against CSFV (Tian Wen Jing, TWJ-E2®), containing a baculovirus-expressed E2 glycoprotein of a genotype 1.1 vaccine strain, was officially licensed in China and commercialized. To evaluate the cross-protective efficacy of TWJ-E2 against different virulent genotype 2 Chinese field isolates (2.1b, 2.1c, 2.1 h, and 2.2), 4-week-old pigs were immunized with the TWJ-E2 vaccine according to the manufacturer's instructions and then challenged with genotype 2 strains. A group vaccinated with the conventional C-strain vaccine was included for comparison. TWJ-E2 vaccinated pigs developed higher levels of E2 and neutralizing antibodies than those receiving the commercial C-strain vaccine. All TWJ-E2 and C-strain vaccinated pigs survived challenge without development of fever, clinical signs or pathological lesions. In contrast, all unvaccinated control pigs displayed severe CSF disease with 40-100% mortalities by 24 days post challenge. None of the TWJ-E2 and C-strain vaccinated pigs developed viremia, viral shedding from tonsils, E^rns protein in the sera, or viral RNA loads in different tissues after challenge, all of which were detected in the challenged unvaccinated controls. We conclude that vaccination of young pigs with TWJ-E2 provides complete immune protection against genotypically heterologous CSFVs and prevents viral shedding after challenge, with an efficacy at least comparable to that elicited by the conventional C-strain vaccine.