Standardized focus assay protocol for biosafety level four viruses

Virucidal activity of three standard chemical disinfectants against Ebola virus suspended in tripartite soil and whole blood

Proper disinfection and inactivation of highly pathogenic viruses is an essential component of public health and prevention. Depending on environment, surfaces, and type of contaminant, various methods of disinfection must be both efficient and available. To test both established and novel chemical disinfectants against risk group 4 viruses in our maximum containment facility, we developed a standardized protocol and assessed the chemical inactivation of the two Ebola virus variants Mayinga and Makona suspended in two different biological soil loads. Standard chemical disinfectants ethanol and sodium hypochlorite completely inactivate both Ebola variants after 30 s in suspension at 70% and 0.5% v/v, respectively, concentrations recommended for disinfection by the World Health Organization. Additionally, peracetic acid is also inactivating at 0.2% v/v under the same conditions. Continued vigilance and optimization of current disinfection protocols is extremely important due to the continuous presence of Ebola virus on the African continent and increased zoonotic spillover of novel viral pathogens. Furthermore, to facilitate general pandemic preparedness, the establishment and sharing of standardized protocols is very important as it allows for rapid testing and evaluation of novel pathogens and chemical disinfectants.

Automation of Infectious Focus Assay for Determination of Filovirus Titers and Direct Comparison to Plaque and TCID50 Assays

Ongoing efforts to develop effective therapies against filoviruses rely, to different extents, on quantifying the amount of viable virus in samples by plaque, TCID₅₀, and focus assays. Unfortunately, these techniques have inherent variance, and laboratory-specific preferences make direct comparison of data difficult. Additionally, human errors such as operator errors and subjective bias can further compound the differences in outcomes. To overcome these biases, we developed a computer-based automated image-processing method for a focus assay based on the open-source CellProfiler software platform, which enables high-throughput screening of many treatment samples at one time. We compared virus titers calculated using this platform to plaque and TCID₅₀ assays using common stocks of virus for 3 major Filovirus species, Zaire ebolavirus, Sudan ebolavirus, and Marburg marburgvirus with each assay performed by multiple operators on multiple days. We show that plaque assays give comparable findings that differ by less than 3-fold. Focus-forming unit (FFU) and TCID₅₀ assays differ by 10-fold or less from the plaque assays due a higher (FFU) and lower (TCID₅₀) sensitivity. However, reproducibility and accuracy of each assay differs significantly with Neutral Red Agarose Overlay plaque assays and TCID₅₀ with the lowest reproducibility due to subjective analysis and operator error. Both crystal violet methylcellulose overlay plaque assay and focus assays perform best for accuracy and the focus assay performs best for speed and throughput.

SINS model in the management of biosafety level 2 laboratories: exploration and practice

A significant number of biosafety level 2 (BSL-2) laboratories have been established in many countries for studies of various types of pathogenic agents and other infectious biological materials. The harmonized management of biological risks in such diverse laboratories thus appears as a real challenge. Zhejiang Province in China has taken the initiative to establish a comprehensively integrated laboratory biosafety management system called SINS (Standardization, Informatization, Normalization and Systematization). The SINS model system has been introduced and adopted in 1,721 BSL-2 laboratories in Zhejiang Province, and thus lead to an increase in the number of biosafety committees from 20% to more than 95% from 2007 to 2018, and the number of biosafety laboratory managers who knows biosafety-related laws and regulations increase from 52.7% to 83.7% from 2009 to 2017. Such achievements indicate that the successful implementation of SINS model has increased the effective control of biological risks in BSL-2 laboratories of the Zhejiang Province. SINS model and its main effects on leading the improvement of laboratory biosafety management was presented in this review. The SINS model helps to strengthen laboratory biosafety and thus effectively reduces occurrence of biosafety-related incidences. This model can potentially be used by other regions or countries where harmonized biosafety management system is still under-developing.

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Zhejiang Province in China took the lead in establishing a comprehensive integrated management system of laboratory biosafety called SINS.

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The SINS model contains Standardization,Informatization, Normalization and Systematization.

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The SINS model can combine the technical with management to strengthen the laboratory biosafety management, and effectively avoid the occurrence of bio-risk.

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SINS model presented in this paper is aimed to cover all aspects in the biosafety management in BSL2 laboratories, consisting of such elements as policy development, administrative supervision, systematic training, documentation and information management.

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SINS model constructed on good experiences in other provinces, serves as a tool for analyzing, checking, and evaluating laboratory management in China.

Diagnostic approaches for Crimean-Congo hemorrhagic fever virus

Introduction: Crimean-Congo hemorrhagic fever (CCHF) is a potentially severe tick-borne viral disease endemic in several regions of Europe, Africa, and Asia. Rapid and reliable diagnosis is essential for early initiation of patient's treatment and for prompt implementation of appropriate precaution and infection control measures to prevent further spread of the disease. Areas covered: A literature search was undertaken on available approaches for laboratory diagnosis of CCHF infections, and the advantages and limitations of the assays are discussed. Expert opinion: Given that the genetic variability among CCHFV strains is high, attention has to be paid on the molecular protocols to detect all currently known genetic lineages of the virus as the emergence of CCHFV strains belonging to various lineages in new environments is not unexpected. In severe cases, the antibody production may be delayed or absent. It is important that the laboratories involved in CCHFV diagnostics to run quality control assays. Standardized assays and point-of-care tests with high sensitivity and specificity are needed. It is expected that the application of next-generation sequencing will be a powerful tool for CCHF diagnostics. Awareness, preparedness, and surveillance are required for prompt detection of CCHF cases.

Periplasmic Nanobody-APEX2 Fusions Enable Facile Visualization of Ebola, Marburg, and Mĕnglà virus Nucleoproteins, Alluding to Similar Antigenic Landscapes among Marburgvirus and Dianlovirus

We explore evolved soybean ascorbate peroxidase (APEX2) as a reporter when fused to the C-termini of llama nanobodies (single-domain antibodies, sdAb; variable domains of heavy chain-only antibodies, VHH) targeted to the E. coli periplasm. Periplasmic expression preserves authentic antibody N-termini, intra-domain disulphide bond(s), and capitalizes on efficient haem loading through the porous E. coli outer membrane. Using monomeric and dimeric anti-nucleoprotein (NP) sdAb cross-reactive within the Marburgvirus genus and cross-reactive within the Ebolavirus genus, we show that periplasmic sdAb–APEX2 fusion proteins are easily purified at multi-mg amounts. The fusions were used in Western blotting, ELISA, and microscopy to visualize NPs using colorimetric and fluorescent imaging. Dimeric sdAb–APEX2 fusions were superior at binding NPs from viruses that were evolutionarily distant to that originally used to select the sdAb. Partial conservation of the anti-Marburgvirus sdAb epitope enabled the recognition of a novel NP encoded by the recently discovered Mĕnglà virus genome. Antibody–antigen interactions were rationalized using monovalent nanoluciferase titrations and contact mapping analysis of existing crystal structures, while molecular modelling was used to reveal the potential landscape of the Mĕnglà NP C-terminal domain. The sdAb–APEX2 fusions also enabled live Marburgvirus and Ebolavirus detection 24 h post-infection of Vero E6 cells within a BSL-4 laboratory setting. The simple and inexpensive mining of large amounts of periplasmic sdAb–APEX2 fusion proteins should help advance studies of past, contemporary, and perhaps Filovirus species yet to be discovered.