One flu, many colors: that is the title of the latest article published in the National Hog Farmer by two faculty members from the University of Minnesota, Drs. Culhane and Rovira. If it is common to talk about one influenza especially in the One Health initiative which reminds us that human and animal health are intricately related, the authors also emphasize that there are “many variants of influenza A viruses [which] paint a complicated picture, sometimes with colors too numerous to grasp with quick glances.”
Because influenza is common to swine, poultry, and human, there are many differences among the strains, enhanced by the variations found between and within geographic locations. This is why our experts recommend to characterize the virus, and go one step further than the one test common to all influenza A.
As they put it themselves, “Influenza A viruses are fascinating, challenging and dynamic” and it is important to determine their colors.
Last Friday, a team of UMN swine nutritionists and veterinarians published the results of their research on the effect of thermal treatments and additives on the inactivation and survival of Porcine Epidemic Diarrhea virus (PEDv) in swine feed. They concluded that both the addition of feed additives and thermal treatments decreased PEDv load in the feed.
Fig 1. Inactivation of PEDV in complete feed when exposed to thermal processing.
The inactivation curves determined by the Weibull model for the survival of PEDV in complete feed at 120°C, 130°C, 140°C, and 145°C.
Abstract: Infection with porcine epidemic diarrhea virus (PEDV) causes diarrhea, vomiting, and high mortality in suckling pigs. Contaminated feed has been suggested as a vehicle of transmission for PEDV. The objective of this study was to compare thermal and electron beam processing, and the inclusion of feed additives on the inactivation of PEDV in feed. Feed samples were spiked with PEDV and then heated to 120–145°C for up to 30 min or irradiated at 0–50 kGy. Another set of feed samples spiked with PEDV and mixed with Ultracid P (Nutriad), Activate DA (Novus International), KEM-GEST (Kemin Agrifood), Acid Booster (Agri-Nutrition), sugar or salt was incubated at room temperature (~25°C) for up to 21 days. At the end of incubation, the virus titers were determined by inoculation of Vero-81 cells and the virus inactivation kinetics were modeled using the Weibull distribution model. The Weibull kinetic parameter delta represented the time or eBeam dose required to reduce virus concentration by 1 log. For thermal processing, delta values ranged from 16.52 min at 120°C to 1.30 min at 145°C. For eBeam processing, a target dose of 50 kGy reduced PEDV concentration by 3 log. All additives tested were effective in reducing the survival of PEDV when compared with the control sample (delta = 17.23 days). Activate DA (0.81) and KEM-GEST (3.28) produced the fastest inactivation. In conclusion, heating swine feed at temperatures over 130°C or eBeam processing of feed with a dose over 50 kGy are effective processing steps to reduce PEDV survival. Additionally, the inclusion of selected additives can decrease PEDV survivability.
Dr. Peter Davies is finishing up his sabbatical year, spent in the Presidential Advisory Council on Combating Antibiotic-Resistant Bacteria and is talking about European regulations on antimicrobials in the National Hog Farmer.
Our graduate students did a fantastic job at the 24th IPVS and we would like to congratulate them all for their hard work. Among them, Dr. Talita Resende won the IPVS award for best poster. Talita is a PhD candidate at the University of Minnesota under the supervision of Dr. Fabio Vannucci and she presented a poster on A novel diagnostic platform for in situ detection and subtyping of Rotaviruses and Influenza A in pigs.
Dr. Mike Murtaugh’s team just recently published a scientific article in Veterinary Microbiology assessing the difference in Porcine Circovirus type 2 (PCV2) prevalence in the US between 2006 and 2012. The conclusion of their study is that the widespread utilization of effective vaccines dramatically decreased the prevalence of the virus in American herds.
Abstract: Porcine circovirus type 2 (PCV2), a small, single-stranded circular DNA virus and the causative agent of porcine circovirus associated disease (PCVAD), was first observed in the mid-1990s in pigs with a post-weaning wasting disease. In 2006 the number of PCVAD cases greatly increased, marking it as an important viral pathogen for the United States (US) swine industry. PCV2 vaccines were introduced to the US in 2006 in response to widespread outbreaks of PCVAD. These vaccines were effective in preventing disease, but did not eliminate virus from the animals. In 2006, prior to vaccine use, a study of PCV2 prevalence in pig herds across the US was performed in conjunction with the US National Animal Health Monitoring System. In 2012, 6 years after widespread PCV2 vaccination, this study was repeated. Since the introduction of PCV2 vaccines in 2006, viral presence and viral loads have greatly decreased, and a genotypic shift dominated by PCV2b has occurred. Antibody levels have decreased in the pig population, but approximately 95% of sites continue to be antibody-positive. Widespread vaccination has controlled PCVAD and decreased PCV2 prevalence to the point that viremia is not detected on many sites. Thus, continued vaccination may lead to PCV2 elimination in the national herd over time.