Contact inactivation of orthopoxviruses by household disinfectants

Evaluation of Stability, Inactivation, and Disinfection Effectiveness of Mpox Virus

BACKGROUND

Mpox virus (MPXV) infections have increased in many countries since May 2022, increasing demand for diagnostic tests and research on the virus. To ensure personnel safety, appropriate and reliable measures are needed to disinfect and inactivate infectious samples; Methods: We evaluated the stability of infectious MPXV cultures stored at different temperatures and through freeze-thaw cycles. Heat physical treatment (56 °C, 70 °C, 95 °C), chemical treatment (beta-propiolactone (BPL)) and two commercialized disinfectants (Micro-Chem Plus (MCP) and ethanol) were tested against infectious MPXV cultures; Results: The results indicated that MPXV stability increases with lower temperatures. The MPXV titer was stable within three freeze-thaw cycles and only decreased by 1.04 log10 (lg) 50% cell culture infective dose (CCID50) per milliliter (12.44%) after twelve cycles. MPXV could be effectively inactivated at 56 °C for 40 min, 70 °C for 10 min, and 95 °C for 5 min. For BPL inactivation, a 1:1000 volume ratio (BPL:virus) could also effectively inactivate MPXV. A total of 2% or 5% MCP and 75% ethanol treated with MPXV for at least 1 min could reduce >4.25 lg; Conclusions: MPXV shows high stability to temperature and freeze-thaw. Heat and BPL treatments are effective for the inactivation of MPXV, while MCP and ethanol are effective for disinfection, which could help laboratory staff operate the MPXV under safer conditions and improve operational protocols.

The Biosafety Research Road Map: The Search for Evidence to Support Practices in the Laboratory-Mpox/Monkeypox Virus

Introduction

The virus formerly known as monkeypox virus, now called mpoxv, belongs to the Orthopoxvirus genus and can cause mpox disease through both animal-to-human and human-to-human transmission. The unexpected spread of mpoxv among humans has prompted the World Health Organization (WHO) to declare a Public Health Emergency of International Concern (PHEIC).

Methods

We conducted a literature search to identify the gaps in biosafety, focusing on five main areas: how the infection enters the body and spreads, how much of the virus is needed to cause infection, infections acquired in the lab, accidental release of the virus, and strategies for disinfecting and decontaminating the area.

Discussion

The recent PHEIC has shown that there are gaps in our knowledge of biosafety when it comes to mpoxv. We need to better understand where this virus might be found, how much of it can spread from person-to-person, what are the effective control measures, and how to safely clean up contaminated areas. By gathering more biosafety evidence, we can make better decisions to protect people from this zoonotic agent, which has recently become more common in the human population.

Rapid and reliable inactivation protocols for the diagnostics of emerging viruses: The example of SARS-CoV-2 and monkeypox virus

The emergence and sustained transmission of novel pathogens are exerting an increasing demand on the diagnostics sector worldwide, as seen with the ongoing severe acute respiratory coronavirus 2 (SARS-CoV-2) pandemic and the more recent public health concern of monkeypox virus (MPXV) since May 2022. Appropriate and reliable viral inactivation measures are needed to ensure the safety of personnel handling these infectious samples. In the present study, seven commercialized diagnosis buffers, heat (56°C and 60°C), and sodium dodecyl sulfate detergent (2.0%, 1.0%, and 0.5% final concentrations) were tested against infectious SARS-CoV-2 and MPXV culture isolates on Vero cell culture. Cytopathic effects were observed up to 7 days postinoculation and viral load evolution was measured by semiquantitative polymerase chain reaction. The World Health Organization recommends an infectious titer reduction of at least 4 log10 . As such, the data show efficacious SARS-CoV-2 inactivation by all investigated methods, with >6.0 log10 reduction. MPXV inactivation was also validated with all investigated methods with 6.9 log10 reductions, although some commercial buffers required a longer incubation period to yield complete inactivation. These results are valuable for facilities, notably those without biosafety level-3 capabilities, that need to implement rapid and reliable protocols common against both SARS-CoV-2 and MPXV.

Human Monkeypox: Oral Implications and Recommendations for Oral Screening and Infection Control in Dental Practice

The World Health Organization declared the spread of the human monkeypox virus (MPXV) an "emerging threat of moderate health concern" on 23 June 2022. Although about 20,000 cases of Monkeypox (MPX) were recorded in Europe and more than 28,000 in the United States from May to October 2022, their number is still small compared to the number of dental patients treated annually. Therefore, the likelihood of oral healthcare workers encountering an MPX case is relatively low in not endemic regions. In addition, MPX-positive individuals are considered contagious only during the prodromal or acute phase. However, the exact shedding and transmission routes of MPX and the associated risk of transmission in the dental setting remain unclear. Moreover, infected subjects whose disease is confined to the head and neck may require oral and dental care because they complain of lymphadenopathy involving the cervical lymph nodes. Furthermore, MPX lesions may first appear in the oral cavity or perioral area. Therefore, given the recent spread of MPXV in non-endemic areas where dentists are not used to considering this disease in the differential diagnosis and taking appropriate preventive measures, all oral healthcare providers nowadays should be aware of the oral presentation of MPX for adequate oral screening and appropriate preventive measures for infection control in the dental practice.

Sanitizing agents for virus inactivation and disinfection

Viral epidemics develop from the emergence of new variants of infectious viruses. The lack of effective antiviral treatments for the new viral infections coupled with rapid community spread of the infection often result in major human and financial loss. Viral transmissions can occur via close human-to-human contact or via contacting a contaminated surface. Thus, careful disinfection or sanitization is essential to curtail viral spread. A myriad of disinfectants/sanitizing agents/biocidal agents are available that can inactivate viruses, but their effectiveness is dependent upon many factors such as concentration of agent, reaction time, temperature, and organic load. In this work, we review common commercially available disinfectants agents available on the market and evaluate their effectiveness under various application conditions. In addition, this work also seeks to debunk common myths about viral inactivation and highlight new exciting advances in the development of potential sanitizing agents.

Hazard Characterization of Modified Vaccinia Virus Ankara Vector: What Are the Knowledge Gaps?

Modified vaccinia virus Ankara (MVA) is the vector of choice for human and veterinary applications due to its strong safety profile and immunogenicity in vivo. The use of MVA and MVA-vectored vaccines against human and animal diseases must comply with regulatory requirements as they pertain to environmental risk assessment, particularly the characterization of potential adverse effects to humans, animals and the environment. MVA and recombinant MVA are widely believed to pose low or negligible risk to ecosystem health. However, key aspects of MVA biology require further research in order to provide data needed to evaluate the potential risks that may occur due to the use of MVA and MVA-vectored vaccines. The purpose of this paper is to identify knowledge gaps in the biology of MVA and recombinant MVA that are of relevance to its hazard characterization and discuss ongoing and future experiments aimed at providing data necessary to fill in the knowledge gaps. In addition, we presented arguments for the inclusion of uncertainty analysis and experimental investigation of verifiable worst-case scenarios in the environmental risk assessment of MVA and recombinant MVA. These will contribute to improved risk assessment of MVA and recombinant MVA vaccines.

Destabilization of α-Helical Structure in Solution Improves Bactericidal Activity of Antimicrobial Peptides: Opposite Effects on Bacterial and Viral Targets

We have previously examined the mechanism of antimicrobial peptides on the outer membrane of vaccinia virus. We show here that the formulation of peptides LL37 and magainin-2B amide in polysorbate 20 (Tween 20) results in greater reductions in virus titer than formulation without detergent, and the effect is replicated by substitution of polysorbate 20 with high-ionic-strength buffer. In contrast, formulation with polysorbate 20 or high-ionic-strength buffer has the opposite effect on bactericidal activity of both peptides, resulting in lesser reductions in titer for both Gram-positive and Gram-negative bacteria. Circular dichroism spectroscopy shows that the differential action of polysorbate 20 and salt on the virucidal and bactericidal activities correlates with the α-helical content of peptide secondary structure in solution, suggesting that the virucidal and bactericidal activities are mediated through distinct mechanisms. The correlation of a defined structural feature with differential activity against a host-derived viral membrane and the membranes of both Gram-positive and Gram-negative bacteria suggests that the overall helical content in solution under physiological conditions is an important feature for consideration in the design and development of candidate peptide-based antimicrobial compounds.

Semliki Forest virus and Sindbis virus, but not vaccinia virus, require glycolysis for optimal replication

Viruses are obligate intracellular pathogens which rely on the cell's machinery to produce the energy and macromolecules required for replication. Infection is associated with a modified metabolic profile and one pathway which can be modified is glycolysis. In this study, we investigated if the glycolysis pathway is required for alphavirus replication. Pre-treatment of Vero cells with three different glycolysis inhibitors (2-deoxyglucose, lonidamine and oxamate) resulted in a significant reduction (but not abrogation) of Semliki Forest virus and Sindbis virus replication, but not of the unrelated virus, vaccinia virus. Reduced virus yield was not associated with any significant cytotoxic effect and delayed treatment up to 3 h post-infection still resulted in a significant reduction. This suggested that glycolysis is required for optimal replication of alphaviruses by supporting post-entry life cycle steps.

A carpet-based mechanism for direct antimicrobial peptide activity against vaccinia virus membranes

Antimicrobial peptides have activity against a wide variety of biological membranes and are an important component of innate immunity in vertebrate as well as invertebrate systems. The mechanisms of action of these peptides are incompletely understood and a number of competing but not necessarily mutually exclusive models exist. In this study we examined the virucidal activity of four peptides, the human cathelicidin derived LL37, Xenopus alanine-substituted Magainin-2 amide, uperin-3.1, and a cecropin-LL37 hybrid against vaccinia virus. The peptides were shown to be differentially virucidal but all were shown to attack the viral envelope, with LL37 being the most effective and uperin-3.1 the least. Density gradient analysis of the treated virions indicated the virus outer membrane was efficiently removed by peptide action and suggests a mechanism of direct virus inactivation that is consistent with the carpet model for peptide-mediated membrane disruption. Interestingly, the least effective peptide uperin-3.1 was equally effective as the others at inducing susceptibility to neutralizing antibody. This suggests that in addition to direct killing by a carpet-based mechanism, the peptides may simultaneously operate a different mechanism that exposes sequestered antigen without membrane removal.

Development of a novel monoclonal antibody with reactivity to a wide range of Venezuelan equine encephalitis virus strains

BACKGROUND

There is currently a requirement for antiviral therapies capable of protecting against infection with Venezuelan equine encephalitis virus (VEEV), as a licensed vaccine is not available for general human use. Monoclonal antibodies are increasingly being developed as therapeutics and are potential treatments for VEEV as they have been shown to be protective in the mouse model of disease. However, to be truly effective, the antibody should recognise multiple strains of VEEV and broadly reactive monoclonal antibodies are rarely and only coincidentally isolated using classical hybridoma technology.

RESULTS

In this work, methods were developed to reliably derive broadly reactive murine antibodies. A phage library was created that expressed single chain variable fragments (scFv) isolated from mice immunised with multiple strains of VEEV. A broadly reactive scFv was identified and incorporated into a murine IgG2a framework. This novel antibody retained the broad reactivity exhibited by the scFv but did not possess virus neutralising activity. However, the antibody was still able to protect mice against VEEV disease induced by strain TrD when administered 24 h prior to challenge.

CONCLUSION

A monoclonal antibody possessing reactivity to a wide range of VEEV strains may be of benefit as a generic antiviral therapy. However, humanisation of the murine antibody will be required before it can be tested in humans.

Alpha interferon as an adenovirus-vectored vaccine adjuvant and antiviral in Venezuelan equine encephalitis virus infection

There are no widely available vaccines or antiviral drugs capable of protecting against infection with Venezuelan equine encephalitis virus (VEEV), although an adenovirus vector expressing VEEV structural proteins protects mice from challenge with VEEV and is potentially a vaccine suitable for human use. This work examines whether alpha interferon (IFN-α) could act as an adjuvant for the adenovirus-based vaccine. IFN-α was either expressed by a plasmid linked to the adenovirus vaccine or encoded by a separate adenovirus vector administered as a mixture with the vaccine. In contrast to previous reports with other vaccines, the presence of IFN-α reduced the antibody response to VEEV. When IFN-α was encoded by adenovirus, the lack of a VEEV-specific response was accompanied by an increase in the immune response to the adenovirus vector. IFN-α also plays a direct role in defence against virus infection, inducing the expression of a large number of antiviral proteins. Adenovirus-delivered IFN-α protected mice from VEEV disease when administered 24 h prior to challenge, but not when administered 6 h post-challenge, suggesting that up to 24 h is required for the development of the IFN-mediated antiviral response.

Traditional smallpox vaccination with reduced risk of inadvertent contact spread by administration of povidone iodine ointment

One concern with traditional smallpox vaccination is inadvertent spread of virus to atopic or immunocompromised contacts. To reduce this risk, we tested the ability of povidone iodine to inactivate infectious virus at the vaccination site beginning at 7 days after transcutaneous smallpox vaccination. This ointment rapidly inactivated virus on the skin without reducing neutralizing antibody titers or antiviral T cell responses. Moreover, there was no delay in healing/eschar separation following povidone iodine application. Together, this indicates that administration of an antiviral/antimicrobial cream can effectively block virus shedding after traditional smallpox vaccination and reduce the risks of autoinoculation or contact spread.

Comparative efficacy of modified vaccinia Ankara (MVA) as a potential replacement smallpox vaccine

International concern over the potential consequences of a Bioterrorist or Biowarfare associated release of variola virus have prompted renewed interest in the vaccines for smallpox. The traditional live, replicating vaccine strains are subject to novel safety concerns associated with historical production methods in domesticated ruminants and the additional hazards that vaccinia virus poses for people with immune system abnormalities or a history of eczematous skin conditions. In this study we have examined the longevity and efficacy of immunity induced by a non-replicating smallpox vaccine candidate, modified vaccinia Ankara (MVA) in a murine model using intranasal and aerosol routes of infection. Two-step vaccinations of MVA followed by traditional Lister vaccine are compared with either Lister alone or MVA alone, and the longevity of the protection induced by MVA is assessed. MVA is found to be broadly similar to Lister. Although protection is shown to decay with time, when administered at a standard human dose the longevity of protection induced by MVA is comparable to that induced by Lister.