Inactivation of classical swine fever virus: association of hydrostatic pressure and ultraviolet irradiation

Survival of surface bacteriophages and their hosts in in situ deep-sea environments

IMPORTANCE

The survival of the sinking prokaryotes and viruses in the deep-sea environment is crucial for deep-sea ecosystems and biogeochemical cycles. Through an in situ deep-sea long-term incubation device, our results showed that viral particles and infectivity had still not decayed completely after in situ incubation for 1 year. This suggests that, via infection and lysis, surface viruses with long-term infectious activity in situ deep-sea environments may influence deep-sea microbial populations in terms of activity, function, diversity, and community structure and ultimately affect deep-sea biogeochemical cycles, highlighting the need for additional research in this area.

Evaluation of Ultraviolet Type C Radiation in Inactivating Relevant Veterinary Viruses on Experimentally Contaminated Surfaces

Many swine farms employ UVC treatment in employees' personal belongings and small tools entering farms as part of the biosecurity protocol to decrease the risk of pathogen introduction into the operation. However, the UVC efficacy in some veterinary viruses is not fully evaluated. This study evaluated the efficacy of ultraviolet type C (UVC) radiation in inactivating seven relevant veterinary viruses: Swine Poxvirus (SwPV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Porcine Epidemic Diarrhea Virus (PEDV), Swine Influenza Virus (SIV), Bovine Viral Diarrhea Virus (BVDV), Porcine Parvovirus (PPV), and Senecavirus A (SVA). The experimentally contaminated materials included polystyrene and filter paper. The samples were exposed to UVC for 5 min (total dose of 360 mJ/cm²). The UVC treatment caused a decrease over 4 log10 in SwPV titer on the polystyrene surface, whereas it consistently reduced about 5 log10 in PPV and SVA samples. No viable virus was recovered from PRRSV, PEDV, SIV, and BVDV samples. In filter paper, conversely, the efficacy was reduced. This study provides essential information on the inactivation effectiveness of a specific dose of UVC on important veterinary viruses, further supporting the rational application and strategic guidance for UVC radiation use to disinfect materials.

Stability of different influenza subtypes: How can high hydrostatic pressure be a useful tool for vaccine development?

BACKGROUND

Avian influenza A viruses can cross naturally into mammals and cause severe diseases, as observed for H5N1. The high lethality of human infections causes major concerns about the real risk of a possible pandemic of severe diseases to which human susceptibility may be high and universal. High hydrostatic pressure (HHP) is a valuable tool for studies regarding the folding of proteins and the assembly of macromolecular structures such as viruses; furthermore, HHP has already been demonstrated to promote viral inactivation.

METHODS

Here, we investigated the structural stability of avian and human influenza viruses using spectroscopic and light-scattering techniques. We found that both particles have similar structural stabilities and that HHP promotes structural changes.

RESULTS

HHP induced slight structural changes to both human and avian influenza viruses, and these changes were largely reversible when the pressure returned to its initial level. The spectroscopic data showed that H3N2 was more pressure-sensitive than H3N8. Structural changes did not predict changes in protein function, as H3N2 fusion activity was not affected, while H3N8 fusion activity drastically decreased. The fusion activity of H1N1 was also strongly affected by HHP. In all cases, HHP caused inactivation of the different influenza viruses.

CONCLUSIONS

HHP may be a useful tool for vaccine development, as it induces minor and reversible structural changes that may be associated with partial preservation of viral biological activities and may potentiate their immunogenic response while abolishing their infectivity. We also confirmed that, although pressure does not promote drastic changes in viral particle structure, it can distinctly affect viral fusion activity.

Intranasal Immunization with Pressure Inactivated Avian Influenza Elicits Cellular and Humoral Responses in Mice

Influenza viruses pose a serious global health threat, particularly in light of newly emerging strains, such as the avian influenza H5N1 and H7N9 viruses. Vaccination remains the primary method for preventing acquiring influenza or for avoiding developing serious complications related to the disease. Vaccinations based on inactivated split virus vaccines or on chemically inactivated whole virus have some important drawbacks, including changes in the immunogenic properties of the virus. To induce a greater mucosal immune response, intranasally administered vaccines are highly desired as they not only prevent disease but can also block the infection at its primary site. To avoid these drawbacks, hydrostatic pressure has been used as a potential method for viral inactivation and vaccine production. In this study, we show that hydrostatic pressure inactivates the avian influenza A H3N8 virus, while still maintaining hemagglutinin and neuraminidase functionalities. Challenged vaccinated animals showed no disease signs (ruffled fur, lethargy, weight loss, and huddling). Similarly, these animals showed less Evans Blue dye leakage and lower cell counts in their bronchoalveolar lavage fluid compared with the challenged non-vaccinated group. We found that the whole inactivated particles were capable of generating a neutralizing antibody response in serum, and IgA was also found in nasal mucosa and feces. After the vaccination and challenge we observed Th1/Th2 cytokine secretion with a prevalence of IFN-γ. Our data indicate that the animals present a satisfactory immune response after vaccination and are protected against infection. Our results may pave the way for the development of a novel pressure-based vaccine against influenza virus.

High hydrostatic pressure for development of vaccines

Disease management in the food industry is complex and includes use of good hygienic practices, antimicrobials, and immunization. Vaccines are available against many, but not all, disease agents affecting animals reared for human food. Fewer vaccines are currently licensed and widely available for human foodborne pathogens. Increased resistance to antimicrobials provides additional impetus to develop new vaccines. In addition to the need for new vaccines, new methods of vaccine production are desired. Some current methods of vaccine production can involve use of hazardous chemicals, provide inconsistent results, or present risk to vaccine recipients with certain allergies. The efficacy of high hydrostatic pressure (HHP) for inactivation of a variety of foodborne pathogenic microorganisms has been well established, and some of these microorganisms have been demonstrated to retain immunogenic properties, suggesting HHP may have application for the development of vaccines. Studies on the effect of HHP on infectivity and immunogenicity of various viruses, a protozoan parasite, and one bacterial species are presented. Control of several of these pathogens is important for animal health and economic stability in several sectors of the food industry. The research to date on the potential for vaccine development by HHP is presented.

Study on continuous (254 nm) and pulsed UV (266 and 355 nm) lights on BVD virus inactivation and its effects on biological properties of fetal bovine serum

Both continuous UV lights and pulsed UV lasers have potentials to inactivate known and emerging viruses. Bovine viral diarrhea virus (BVDV), from the Pestivirus genus, is known to be a common viral contamination in (fetal) bovine serum (FBS). Also, BVDV has been used in the blood product industry as a surrogate for Hepatitis C virus (HCV), due to its similarity in structure and genome. Germicidal UV lamp with the wavelength of 254 nm and Nd:YAG laser (pulsed UV laser) in its third and fourth harmonic with the wavelengths of 355 and 266 nm, respectively, were used. BVDV suspended in PBS or FBS were exposed to different intensities and doses and then reduction in BVDV titer were calculated. To complete inactivation of BVDV suspended in PBS and PBS containing 5% FBS, 1.6 (t=30 min) and 3.2 (t=60 min)J/cm(2) were used. The minimum doses for inactivation of BVDV suspended in PBS with the 355 and 266 nm of pulsed UV laser were 352 and 92.25 J/cm(2). Also, the minimum doses for inactivation of BVDV suspended in FBS with 355 and 266 nm wavelengths of pulsed UV laser were 704 and 127 J/cm(2). To evaluate the irradiated FBS quality to support cell culture growth, FBS was treated with the dose of 190.5 J/cm(2) and 266 nm pulsed UV laser and was used to grow Vero cells, in comparison with a control group. The viability of cells in two groups was identical and the statistical evaluation showed no significant difference in 12 passages.

Inactivation of Hantaan Virus-Containing Samples for Subsequent Investigations outside Biosafety Level 3 Facilities

OBJECTIVES

The potential risk of accidental infection by hantaviruses in a clinical or research laboratory necessitates special precautionary measures. A biosafety program must address handling and disposal of infectious materials as well as appropriate virus inactivation or depletion procedures to permit necessary further processing of specimens outside the biosafety level 3 laboratory.

METHODS

To study the elimination of hantavirus infectivity, the effects of different chemical and physical inactivation and depletion procedures were investigated on Hantaan virus-containing materials. An infectivity assay for hantaviruses was utilised to verify these procedures which are commonly preceding investigations such as ELISA, flow cytometry analysis, Western blot or immunofluorescence assay.

RESULTS

Chemical inactivation with methanol, paraformaldehyde, acetone/methanol and detergent-containing lysis buffer as well as physical forces such as UV irradiation and filtration efficiently reduced viral infectivity in infected cells and their supernatants below the detection limit.

CONCLUSION

The virus inactivation and depletion methods described herein are suitable to prepare non-infectious samples for further use in immunological, virological and cell-biological assays.

Pressure-inactivated FMDV: a potential vaccine

Foot-and-mouth disease virus (FMDV) is the causative agent of the foot-and-mouth disease (FMD). Alternative FMD vaccines have been pursued due to important disadvantages of the one currently in use. High hydrostatic pressure (HP) has been observed to inactivate some viruses. Here, we investigated the effects of HP on FMDV O1 Campos-Vallée (CVa) infectivity. A treatment consisting of 2.5 kbar at -15 degrees C and 1M urea, completely abolished FMDV infectivity, maintaining the integrity of its capsid structure. Moreover, its ability to elicit neutralizing antibody production in rabbits was preserved. Taken together, our results suggest that HP could be a safe, simple, cheap and reproducible way for viral vaccine production.