Physical integrity of herpes simplex virus following thermal inactivation

Immune Priming of Pacific Oysters (Crassostrea gigas) to Induce Resistance to Ostreid herpesvirus 1: Comparison of Infectious and Inactivated OsHV-1 with Poly I:C

Pacific oyster mortality syndrome (POMS), which is caused by Ostreid herpesvirus 1 (OsHV-1), causes economic losses in Pacific oyster (Crassostrea gigas) aquaculture in many countries. Reducing the mortality in disease outbreaks requires changing the host, pathogen and environment interactions to favor the host. Survivors of natural exposure to OsHV-1 are able to survive subsequent outbreaks. This has been replicated under laboratory conditions, suggesting the existence of an immune response. The aim of the present study is to compare the effects of prior exposure to infectious OsHV-1, heat-inactivated OsHV-1 and the chemical anti-viral immune stimulant poly I:C on mortality following exposure to virulent OsHV-1. All treatments were administered by intramuscular injection. Oysters were maintained at 18 °C for 14 days; then, the temperature was increased to 22 °C and the oysters were challenged with virulent OsHV-1. Heat-inactivated OsHV-1, infectious OsHV-1 and poly I:C all induced significant protection against mortality, with the hazard of death being 0.41, 0.18 and 0.02, respectively, compared to the controls, which had no immune priming. The replication of OsHV-1 on first exposure was not required to induce a protective response. While the underlying mechanisms for protection remain to be elucidated, conditioning for resistance to POMS by prior exposure to inactivated or infectious OsHV-1 may have practical applications in oyster farming but requires further development to optimize the dose and delivery mechanism and evaluate the duration of protection.

Optimization of non-detergent treatment for enveloped virus inactivation using the Taguchi design of experimental methodology (DOE)

In mammalian cell culture technology, viral contamination is one of the main challenges; and, so far, various strategies have been taken to remove or inactivate viruses in the cell-line production process. The suitability and feasibility of each method are determined by different factors including effectiveness in target virus inactivation, maintaining recombinant protein stability, easiness-in terms of the process condition, cost-effectiveness, and eco-friendliness. In this research, Taguchi design-of-experiments (DOE) methodology was used to optimize a non-detergent viral inactivation method via considering four factors of temperature, time, pH, and alcohol concentration in an unbiased (orthogonal) fashion with low influence of nuisance factors. Herpes Simplex Virus-1 (HSV1) and Vero cell-line were used as models for enveloped viruses and cell-line, respectively. Examining the cytopathic effects (CPE) in different dilutions showed that pH (4), alcohol (15%), time (120 min), and temperature (25 °C) were the optimal points for viral inactivation. Evaluating the significance of each parameter in the HSV-1 inactivation using Taguchi and ANOVA analyses, the contributions of pH, alcohol, temperature and time were 56.5%, 19.2%, 12%, and 12%, respectively. Examining the impact of the optimal viral treatment condition on the stability of model recombinant protein-recombinant human erythropoietin, no destabilization was detected.

Effect of temperature, medium composition, and cell passage on production of herpes-based viral vectors

Our work uses replication-defective genomic herpes simplex virus type-1 (HSV-1)-based vectors to transfer therapeutic genes into cells of the central nervous system and other tissues. Obtaining highly purified high-titer vector stocks is one of the major obstacles remaining in the use of these vectors in gene therapy applications. We have examined the effects of temperature and media conditions on the half-life of HSV-1 vectors. The results reveal that HSV stability is 2.5-fold greater at 33 degrees C than at 37 degrees C and is further stabilized at 4 degrees C. Additionally, a significantly higher half-life was measured for the vector in infection culture conditioned serum medium compared to fresh medium with or without serum. Synchronous infections incubated at 33 degrees C produced 2-fold higher amounts of vector than infected cells incubated at 37 degrees C, but with a lag of 16-24 h. Vector production yielded 3-fold higher titers and remained stable at peak levels for a longer period of time in cultures incubated at 33 degrees C than 37 degrees C. A pronounced negative effect of increased cell passage number on vector yield was observed. Vector production at 33 degrees C yielded similar levels regardless of passage number but was reduced at 37 degrees C as passage number increased. Together, these results contribute to improved methods for high-titer HSV vector production.

Delta-9-tetrahydrocannabinol augments murine retroviral induced immunosuppression and infection

Delta-9-tetrahydrocannabinol (THC), the major psychoactive component in marijuana, and the murine retrovirus, Friend leukemia virus (FLV), have been demonstrated to depress cellular immune function, including lymphocyte blastogenic transformation and natural killer cell activity. The present study demonstrates tht the two agents can work in concert to depress these immune activities more severely than either agent administered by itself. When 7.5-10 micrograms/ml THC was added in vitro to spleen cells from mice infected 2-4 weeks earlier with FLV there was a noticeable decrease, beyond that seen with the drug or virus alone, for both lymphocyte blastogenesis and natural killer cell cytotoxicity. In addition, when both FLV and THC were administered to mice concurrently with infection by herpes simplex virus (HSV), mortality attributed to the retrovirus infection occurred significantly more rapidly than in the absence of the drug and HSV. The data indicate that THC acted in the presence of a HSV infection to enhance the FLV induced mortality. By extrapolation to the human condition, these results suggest that marijuana could serve as a cofactor, possibly in conjunction with opportunistic pathogens, in the progression of infection due to the human immunodeficiency virus from latency to overt acquired immunodeficiency syndrome.

The effect of some common inactivation procedures on the antigens of bovine herpesvirus 1

Bovine embryonic kidney cells were infected with bovine herpesvirus 1 (BHV1) or were sham-inoculated. When cytopathic effect was apparent, the cells were treated with beta-propiolactone, formalin, heat (56 degrees C), or ultraviolet irradiation until the virus was inactivated. Infected-treated, infected-untreated (IU) and sham-inoculated cultures were solubilized using Triton X-100 detergent. Resulting preparations were tested by 2-dimensional- and fused rocket-immunoelectrophoresis and were evaluated for their ability to inhibit virus neutralization by BHV1 antiserum. Eleven viral antigens were detected consistently in IU preparations, which strongly inhibited virus neutralization. Eight or more IU antigens were detected in beta-propiolactone-treated, formalin-treated and heat-treated preparations; these inhibited virus neutralization less strongly than the IU preparations. No IU antigens were detected in ultraviolet-treated preparations, nor did this material inhibit virus neutralization. One of the IU antigens was reduced preferentially by all treatments. The selective destruction of antigens by the various treatments might allow antigen-specific serological testing to distinguish vaccinated from naturally-exposed cattle.