Virus inactivation

Sammanfattning: Animal by-products (ABP) Category 3 includes hatchery waste, and also slaughterhouse waste and manure, aimed for use in biogas production. In order to be used as fertilisers, they must be sanitised to reduce pathogenic microorganisms. The initial European regulations regarding processing standards for ABP intended for use in e.g. biogas plants (EC No. 1774/2002) stipulated thermal treatment at 70°C for 60 min. A subsequent amendment (EC No. 208/2006) stated that a validated treatment process may be used if it can show a reduction in thermo-resistant viruses of at least 3 log10, whenever deamed a risk. Thermal treatments of biogas substrate at 70°C and at 55°C, using porcine parvovirus and swine vesicular disease virus, were performed. As a chemical sanitisation process regarding hatchery waste, ammonia inactivation was tested using the highly pathogenic avian influenza virus H7N1 and the low pathogenic avian influenza virus H5N3. Models for other avian pathogenic ssRNA viruses were bovine parainfluenza virus 3, feline calicivirus and feline coronavirus. As possible indicators for monitoring virus inactivation, bacteriophages MS2, ΦX174, and 28b were evaluated. Thermal treatment at 70°C for 60 min inactivated porcine parvovirus by 2.6 log10, while phage 28b was unaffected. Swine vesicular disease virus was undetectable after 30 min. Using too thermostable viruses as models for sufficient virus reduction in thermal treatments regarding Category 3 ABP materials and manure intended for biogas or composting plants, according to EU regulations, would make demands on other time-temperature combinations very strict. All viruses tested were efficiently inactivated by ammonia treatment in hatchery waste, while phage ΦX174 proved too conservative to be used as indicator. Using phage MS2 as a stable indicator to monitor a 3 log10 reduction of ssRNA virus showed that addition of 0.5% w/w ammonia is required, followed by storage for at least 31 h at ≥14°C. In case of an outbreak of e.g. avian influenza, storage for two days at the same conditions was estimated.