Study on inactivation of porcine epidemic diarrhoea virus, porcine sapelovirus 1 and adenovirus in the production and storage of laboratory spray‐dried porcine plasma

Hulst, M.M.; Heres, L.; Hakze‐van der Honing, R.W.; Pelser, M.; Fox, M.; van der Poel, W.H.M.

AIM: Evaluation of the thermal and physical conditions for inactivation of adenovirus (AdV), porcine sapelovirus 1 (PSV1) and the economically important viruses porcine epidemic diarrhoea virus (PEDV) and porcine circovirus 2 (PCV2) in the production of spray‐dried porcine plasma (SDPP). METHODS AND RESULTS: Citrate‐treated porcine plasma of pH 7·5, 9·8 and 10·2 (8·5% dry‐matter) was spiked with PEDV, PSV1, PCV2 and AdV and incubated at 3°C for maximum 24 h, and at 44 or 48°C for maximum 10 min (Experiment 1). Spiked citrate‐treated concentrated plasma of pH 7·5 and 9·8 (24% dry‐matter) was spray dried in a laboratory scale apparatus (Experiment 2). Aliquots of SDPP were stored over a period of 0–10 weeks at 11 and 20°C (Experiment 3). Reverse transcription(RT)‐quantitative PCR detected no notable reduction in viral genomes in treated plasma and SDPP samples. No infectious PSV1 was re‐isolated from plasma and SDPP samples in cell culture. At pH 10·2 and 3°C, infectivity of PEDV in plasma was reduced with a reduction factor of 4·2 log 10 (LRF) at 10 h contact time, whereas heating to 44°C for at least 1 min at alkali pH was needed to achieve a LRF of 4·2 for AdV. Spray drying at an outlet temperature of 80°C reduced AdV infectivity effectively (LRF = 5·2) and PEDV infectivity for 95% (LRF = 1·4). After storage at 20°C for 2 weeks no infectious PEDV was re‐isolated from SDPP anymore (LRF ≥4·0). Due to growth of antibiotic‐resistant bacteria from plasma in cell cultures used for PCV2 isolation, no data regarding inactivation of PCV2 were obtained. CONCLUSIONS: Five percent of PEDV stayed infectious after our spray drying conditions. Spray drying in combination with storage for ≥2 weeks at 20°C eliminated infectivity of PEDV effectively. SIGNIFICANCE AND IMPACT OF THE STUDY: The conditions for inactivation of virus in plasma and SDPP determined are important for producers to inactivate PEDV during production of SDPP.