Thermal Inactivation Of Virus Research Articles

Thermal Inactivation of Viruses and Bacteria with Hot Air Bubbles in Different Electrolyte Solutions

Inactivation of viruses has been an insuperable inhibition to the use of recycled water. Substantial success in solving the problem has recently been achieved using a hot column evaporator (HBCE). Here we extend the technique to inactivate E.coli and MS2 viruses in different electrolyte solutions (0.17M NaCl and 0.01M CaCl2). An increase in the inlet air temperature, from 103°C to 250°C, substantially improved the destruction of both pathogenic groups in either solution. E.coli proved to be more susceptible than viruses to inactivation in the HBCE. The phenomenon of inhibition of bubble coalescence above 0.17M for the NaCl solutions makes the HBCE process for this solution more efficient than for CaCl2 solutions. In part, this is because of the higher air/water interfacial area with NaCl.

Co-culture with Enterobacter cloacae does not Enhance Virus Resistance to Thermal and Chemical Treatments.

Human noroviruses (hNoV) are the primary cause of foodborne disease in the USA. Most studies on inactivation kinetics of hNoV and its surrogates are performed in monoculture, while the microbial ecosystem effect on virus inactivation remains limited. This study investigated the persistence of hNoV surrogates, murine norovirus (MNV) and Tulane virus (TuV), along with Aichi virus (AiV) under thermal and chemical inactivation in association with Gram-negative (Enterobacter cloacae) bacteria. Thermal inactivation of viruses in co-culture with E. cloacae revealed no protective effects of bacteria. At 56°C, AiV with and without bacteria was completely inactivated by 10min with decimal reduction values (D-values) of 41 and 43s, respectively. Similar results were also observed for TuV. Conversely, MNV with bacteria was completely inactivated by 10min while MNV alone remained stable up to 30min at 56°C. Both MNV and TuV were slightly more stable than AiV at 63°C with TuV detection up to 2min without bacteria. For chemical inactivation on stainless steel surfaces, viruses alone and in association with bacteria were treated with 1000ppm sodium hypochlorite. Virus association with bacteria had no significant effect (p > 0.05) on virus resistance to bleach inactivation compared to virus alone. Specifically, exposure to 1000ppm bleach for 5min resulted in an average of 3.86, 2.14, and 0.94 log10 PFU/ml reductions for TuV, MNV, and AiV without bacteria, respectively. Reductions in TuV, MNV, and AiV were 3.50, 1.88, and 0.61 log10 PFU/ml when associated with E. cloacae, respectively.

Inactivation of Aerosolized Viruses in Continuous Air Flow with Axial Heating

Thermal inactivation of viruses has been studied in relevance to food sterilization, water purification, and other “non-aerosol” applications, in which heat treatment is applied for a relatively long time. No data are available on the inactivation of airborne viruses exposed to dry heat for a short time, although this is relevant to bio-defense and indoor air quality control. In this study, we investigated inactivation of aerosolized MS2 viruses in a continuous air flow chamber with axial heating resulted from exposures during ∼ 0.1–1 s. For an airborne virion, the characteristic exposure temperature, T e , was defined utilizing the air temperature profiles in the chamber. The tests were conducted at two air flow rates, Q, which allowed for establishing different thermal flow regimes and exposure time intervals. The experimentally determined inactivation factor, IF, was subjected to correction to account for the temperature profiles. At T e up to ∼ 90°C (Q = 18 L/min) and up to ∼ 140°C (Q = 36 L/min), the...

SCH 38057: a picornavirus capsid-binding molecule with antiviral activity after the initial stage of viral uncoating

The activity of a new water-soluble molecule, SCH 38057, against picornaviruses is described. SCH 38057 inhibited plaque formation of selected entero- and rhinoviruses in a range of 10.2 to 29.1 μM (50% endpoint) and had a therapeutic index of 10 against poliovirus type 2 (polio 2) in HeLa cells. When administered orally or subcutaneously, SCH 38057 protected mice infected with either coxsackievirus B3 (CVB3) or echovirus-9 from mortality. The molecule provided a low level of protection against thermal inactivation of virus, indicating that SCH 38057 interacts with the picornavirus capsid. Binding studies with [ 3H]SCH 38057 revealed that the molecule binds to CVB3 and human rhinovirus 14 (HRV14) in a ratio of 29 and 19 molecules per viral particle, respectively. The affinity constant for SCH 38057 binding to CVB3 was 7.0 × 10 −4 M. When added to cultures of infected cells at 3 h after infection, SCH 38057 markedly inhibited viral RNA synthesis. This finding with lack of inhibition of attachment and loss of infectious virus after attachment were interpreted to indicate that, although SCH 38057 binds to the viral capsid, the molecule exerts its antiviral effect after the initial stage of picornavirus uncoating, i.e., after conversion of the 156S infectious viral particle to smaller subviral species.

Inactivation of viruses in labile blood derivatives. II. Physical methods.

The thermal inactivation of viruses in labile blood derivatives was evaluated by addition of marker viruses (VSV, Sindbis, Sendai, EMC) to anti-hemophilic factor (AHF) concentrates. The rate of virus inactivation at 60 degrees C was decreased by at least 100- to 700-fold by inclusion of 2.75 M glycine and 50 percent sucrose, or 3.0 M potassium citrate, additives which contribute to retention of protein biologic activity. Nonetheless, at least 10(4) infectious units of each virus was inactivated within 10 hours. Increasing the temperature from 60 to 70 or 80 degrees C caused a 90 percent or greater loss in AHF activity. An even greater decline in the rate of virus inactivation was observed on heating AHF in the lyophilized state, although no loss in AHF activity was observed after 72 hours of heating at 60 degrees C. Several of the proteins present in lyophilized AHF concentrates displayed an altered electrophoretic mobility as a result of exposure to 60 degrees C for 24 hours. Exposure to lyophilized AHF to irradiation from a cobalt 60 source resulted in an acceptable yield of AHF at 1.0, but not at 2.0, megarads. At 1 megarad, greater than or equal to 6.0 logs of VSV and 3.3 logs of Sindbis virus were inactivated.

Heat therapy of virus-infected cultures of the cultivated mushroom Agaricus bisporus

A procedure for elimination of viruses by heat treatment of virus-infected isolates of the cultivated mushroom Agaricus bisporus has been perfected. A minimum treatment time of 3 weeks at 33�C was required. The effect of heat treatment was assessed in terms of increased growth of the isolates in vitro and absence of virus particles. Growth rate was not always a good measure of effective heat treatment. Some virus-infected isolates were found which can act as symptomless carriers. The effect of heat treatment appeared to depend on the pre-treatment which the isolates had received. Elimination of viruses did not occur when the isolates were grown at 25� prior to heat treatment. It appears, therefore, that thermal inactivation of viruses is not complete in mature mycelium.