Static Aerated Composting of African Swine Fever Virus-Infected Swine Carcasses with Rice Hulls and Sawdust.

Identifying and ensuring the inactivation of the African Swine Fever virus in deadstock is a gap in the swine industry's knowledge and response capabilities. The results of our study demonstrate that ASFv in deadstock was inactivated using static aerated composting as the carcass disposal method. Replicated compost piles with whole market hogs and two different carbon sources were constructed. In-situ bags containing ASFv-infected spleen tissue were placed alongside each of the carcasses and throughout the pile. The bags were extracted at days 0, 1, 3, 7, 14, 28, 56, and 144 for ASFv detection and isolation. Real-time PCR results showed that DNA of ASFv was detected in all samples tested on day 28. The virus concentration identified through virus isolation was found to be below the detection limit by day 3 in rice hulls and by day 7 in sawdust. Given the slope of the decay, near-zero concentration with 99.9% confidence occurred at 5.0 days in rice hulls and at 6.4 days in sawdust. Additionally, the result of virus isolation also showed that the virus in bone marrow samples collected at 28 days was inactivated.

Viability of African Swine Fever Virus with the Shallow Burial with Carbon Carcass Disposal Method.

African swine fever (ASF) is a highly contagious swine disease with high mortality. In many countries, culling pigs infected and exposed to the ASF virus is mandatory to control the disease, which poses a real challenge in the disposal of large numbers of carcasses during ASF outbreaks. Shallow burial with carbon (SBC) Thanks ew mortality disposal method developed from deep burial and composting. The present study investigates the effectiveness of SBC in disposing of ASF virus-infected pigs. The real-time PCR results showed that DNA of the ASF virus was still detected in bone marrow samples on day 56, while the virus isolation test revealed that the infectious ASF virus was destroyed in both spleen and bone marrow samples on day 5. Interestingly, decomposition was found to occur rapidly in these shallow burial pits. On day 144, only large bones were found in the burial pit. In general, the results of this study indicated that SBC is a potential method for the disposal of ASF-infected carcasses; however, further studies are needed to provide more scientific evidence for the efficacy of SBC in different environment conditions.

Genomic characterization and application of a novel bacteriophage STG2 capable of reducing planktonic and biofilm cells of Salmonella.

As one major foodborne pathogen, Salmonella can cause serious food poisoning outbreaks worldwide. Bacteriophage therapy is increasingly considered as one of the promising antibacterial agents for the biocontrol of foodborne pathogens. In the current study, a lytic phage STG2 capable of infecting S. enteritidis and S. typhimurium was characterized, and its efficacy in reducing these foodborne pathogens in both planktonic and biofilm forms was evaluated on cabbage and various surfaces. Genomic characterization revealed that phage STG2 was Siphoviridae phage (Epseptimavirus genus) with a dsDNA genome comprising of 114,275 bp and its genome does not contain any genes associated to antibiotic resistance, toxins, lysogeny, or virulence factors. Additionally, phage STG2 exhibited great efficacy in reducing (>2 Log) planktonic cells on cabbage as well as the biofilms formed on cabbage, polystyrene, and stainless steel, suggesting that phage STG2 is capable of simultaneously controlling both S. enteritidis and S. typhimurium contaminations on food and food-related surfaces.

The use of composting for the disposal of African swine fever virus-infected swine carcasses.

African swine fever (ASF) has been considered as one of the most important and devastating swine diseases with high mortality rates. Since effective vaccines and treatment are not available, mass euthanasia of infected and exposed pigs has been known to be the best measure to control ASF. Although composting has been proved to be a safe method for the rapid disposal of animal carcasses during outbreaks, there is no information about the effect of composting on the viability of ASF virus in swine carcasses. This study investigates the survival of the ASF virus in swine carcasses during composting. The findings suggested that the DNA of the ASF virus was detected in all samples tested. On the contrary, infectious ASF virus particles were rapidly destroyed at day 3.

Skewness in the literature on infectious livestock diseases in an emerging economy - the case of Vietnam.

Livestock production has increased in many emerging economies, but productivity is often substantially impaired by infectious diseases. The first step towards improved livestock health and productivity is to map the presence of livestock diseases. The objective of this review was to summarize studies conducted on such diseases in an emerging economy, Vietnam, and thereby identifying knowledge gaps that may inform the design of surveillance and control programs. Few studies were found to evaluate the distribution of infectious livestock diseases other than avian influenza. Also, many regions with dense livestock populations had received little attention in terms of disease investigation. A large proportion of the studies dealt with zoonoses and food-borne infections which might be due to funding agencies priorities. On the contrary, studies targeting infections that affect livestock and their productivity were few. We think that this limitation in scientific reports on infectious diseases that only affect livestock productivity is a common phenomenon in low and lower middle income countries. More science-based data on such diseases would help policymakers to prioritize which livestock diseases should be subject to animal health programs aimed to support rural livelihoods and economic development.

Isolation, characterization and application of a polyvalent phage capable of controlling Salmonella and Escherichia coli O157:H7 in different food matrices.

Salmonella Enteritidis, Salmonella Typhimurium, and Escherichia coli O157:H7 are the most important foodborne pathogens, causing serious food poisoning outbreaks worldwide. Bacteriophages are increasingly considered as novel antibacterial agents to control foodborne pathogens. In this study, 8 Salmonella phages and 10 E. coli O157:H7 phages were isolated from chicken products. A polyvalent phage PS5 capable of infecting S. Enteritidis, S. Typhimurium, and E. coli O157:H7 was further characterized and its efficacy in reducing these foodborne pathogens was evaluated in in vitro and in foods. Morphology, one-step growth, and stability assay showed that phage PS5 was a myovirus, with relatively short latent periods, large burst sizes, and high stability. Genome sequencing analysis revealed that the genome of PS5 does not contain any genes associated to antibiotic resistance, toxins, lysogeny, and virulence factors. In broth, phage PS5 significantly decreased the viable counts of all the three bacterial hosts by more than 1.3 log CFU/mL compared to controls after 2 h of incubation at 4 °C and 24 °C. In foods, treatment with PS5 also resulted in significant reductions of viable counts of all the three bacterial hosts compared to controls at temperatures tested. This is the first report on single phage capable of simultaneously controlling S. Enteritidis, S. Typhimurium and E. coli O157:H7 in both in vitro and in foods.

Isolation and application of bacteriophages alone or in combination with nisin against planktonic and biofilm cells of Staphylococcus aureus.

Staphylococcus aureus is a notorious foodborne pathogen since it has ability to produce variety of toxins including heat-stable enterotoxin, form biofilm, and acquire resistance to antibiotics. Biocontrol of foodborne pathogens by lytic bacteriophages garners increasing interest from both researchers and food industry. In the present study, 29 phages against S. aureus were successfully isolated from chicken, pork, and fish. Characterization of the isolates revealed that phage SA46-CTH2 belonging to Podoviridae family had a number of features suitable for food industry applications such as wide host range, short latent period, large burst size, high stress tolerance, and a genome free of virulence genes. Furthermore, phage SA46-CTH2 alone or in combination with nisin exhibited great efficacy in reducing planktonic and biofilm cells of S. aureus at various conditions tested. The combination of phage SA46-CTH2 and nisin was also found to be able to inhibit the regrowth of S. aureus at both 37 and 24 °C.Key points• A total of 29 S. aureus phages were successfully isolated from fish, pork, and chicken products. • Phage SA46-CTH2 was characterized by host range, morphology, and genome sequencing. • SA46-CTH2 significantly reduced both planktonic and biofilm cells of S. aureus. • Combination of SA46-CTH2 and nisin inhibited the regrowth of S. aureus.

Application of bacteriophages in simultaneously controlling Escherichia coli O157:H7 and extended-spectrum beta-lactamase producing Escherichia coli.

Shiga toxin-producing Escherichia coli (STEC) O157:H7 and extended-spectrum beta-lactamase (ESBL) producing E. coli (ESBLEC) are important bacteria of public health concern and frequently isolated from raw beef products. Bacteriophage-based methods have been increasingly exploited to control bacterial contamination in meats. Here, we describe the isolation, characterization, and application of a lytic phage PE37 for the simultaneous bio-control of STEC O157:H7 and ESBLEC. Phage PE37, isolated from the bovine intestine, was morphologically characterized as a member of the Myoviridae family, with a broad host range and great stability under various stress conditions. Sequencing analysis revealed that the genomic DNA of phage PE37 contains genes that contribute to virion structure, replication, assembly, and host lysis. PE37 significantly reduced the viable counts of STEC O157:H7 by 4.9 and 2.6 log CFU/mL in broth after 6 h of incubation at 25 and 8 °C, respectively. Application of phage PE37 to raw beef artificially contaminated with STEC O157:H7 resulted in significant reductions in the viable counts by 2.3 and 0.9 log CFU/piece after 24 h of storage at 25 and 8 °C, respectively. Treatment of raw beef contaminated with a bacterial cocktail of STEC O157:H7 and ESBLEC with PE37 also significantly decreased the viable counts of the bacterial mixture by 1.4 and 1.0 log CFU/piece after 24 h of incubation at 25 and 8 °C, respectively. These findings suggest that bacteriophage PE37 may be a potential bio-agent for controlling STEC O157:H7 and ESBLEC contamination in raw beef.

Identification of the newly identified subtilase cytotoxin-encoding gene (subAB2-2) among clinical Shiga toxin-producing Escherichia coli isolates.

Subtilase cytotoxin (SubAB) is an important virulence factor of eae-negative Shiga toxin-producing Escherichia coli (STEC). Three variants of SubAB-encoding genes have been reported in the literature; however, the newly described subAB variant (subAB2-2) was found only in STEC strains from deer meat, sheep, and some wild animals. In this study, subAB variants were detected by PCR and DNA sequencing in 5 out of 12 (41.6%) eae-negative STEC strains isolated from patients. Most subAB-positive STEC strains (80%) harbored the subAB1 gene. The subAB2-2 gene was detected for the first time in the clinical STEC O128:H2 strain. Other virulence genes including stx1a, stx1c, stx2b, ehxA, and tia were also detected in this strain. The DNA sequence analyses of the subAB1 and subAB2-2 genes of the clinical STEC strains showed 99% and 100% identity to those of the reference strains 98NK2 and LM27558stx2, respectively. This is the first report on the detection of the subAB2-2 gene in a clinical STEC isolate.