Detection of bovine viral diarrhoea virus nucleic acid, but not infectious virus, in bovine serum used for human vaccine manufacture

Suitability of NIID-MDCK cells as a substrate for cell-based influenza vaccine development from the perspective of adventitious virus susceptibility

The practical use of cell-based seasonal influenza vaccines is currently being considered in Japan. From the perspective of adventitious virus contamination, we assessed the suitability of NIID-MDCK cells (NIID-MDCK-Cs) as a safe substrate for the isolation of influenza viruses from clinical specimens. We first established a sensitive multiplex real-time PCR system to screen for 27 respiratory viruses and used it on 34 virus samples that were isolated by passaging influenza-positive clinical specimens in NIID-MDCK-Cs. Incidentally, the limit of detection of the system was 100 or fewer genome copies per reaction. In addition to influenza viruses, human enterovirus 68 (HEV-D68) genomes were detected in two samples after two or three passages in NIID-MDCK-Cs. To further investigate the susceptibility of NIID-MDCK-Cs to adventitious viruses, eight common respiratory viruses were subjected to passages in NIID-MDCK-Cs. The genome copy numbers of seven viruses other than parainfluenza 3 decreased below the limit of detection (LOD) by passage 4. By passaging in NIID-MDCK-Cs, the genome numbers of the input HEV-D68, 1 x 10⁸ copies, declined to 10² at passage 3 and to under the LOD at passage 4, whereas those of the other six viruses were under the LOD by passage 3. These results implied that during the process of isolating influenza viruses with NIID-MDCK-Cs, contaminating viruses other than parainfluenza 3 can be efficiently removed by passages in NIID-MDCK-Cs. NIID-MDCK-Cs could be a safe substrate for isolating influenza viruses that can be used to develop cell-based influenza vaccine candidate viruses. This article is protected by copyright. All rights reserved.

Food safety considerations and research priorities for the cultured meat and seafood industry

Cell-cultured meat and seafood offer a sustainable opportunity to meet the world's increasing demand for protein in a climate-changed world. A responsible, data-driven approach to assess and demonstrate safety of cell-cultured meat and seafood can support consumer acceptance and help fully realize the potential of these products. As an initial step toward a thorough demonstration of safety, this review identifies hazards that could be introduced during manufacturing, evaluates applicability of existing safety assessment approaches, and highlights research priorities that could support safe commercialization. Input was gathered from members of the cultured meat and seafood industry, researchers, regulators, and food safety experts. A series of workshops were held with 87 industry representatives and researchers to create a modular manufacturing process diagram, which served as a framework to identify potential chemical and biological hazards along the steps of the manufacturing process that could affect the safety of a final food product. Interviews and feedback on draft documents validated the process diagram and supported hazard identification and evaluation of applicable safety methods. Most hazards are not expected to be novel; therefore, safety assessment methods from a range of fields, such as conventional and novel foods, foods produced from biotechnology, pharmaceuticals, and so forth, are likely to be applicable. However, additional assessment of novel inputs or products with significant differences from existing foods may be necessary. Further research on the safety of the inputs and associated residues, potential for contamination, and development of standardized safety assessment approaches (particularly animal-free methods) is recommended.

Development of a Quantitative One-Step RT-PCR Method for the Detection of Sabin 2 Virus Contamination in a Novel Oral Poliovirus Vaccine Type 2

To control circulating vaccine-derived type 2 poliovirus outbreaks, a more genetically stable novel Oral Poliovirus Vaccine type 2 (nOPV2) was developed by targeted modifications of Sabin 2 genome. Since the use of OPV2 made of Sabin 2 strain has been stopped, it is important to exclude the possibility that batches of nOPV2 are contaminated with Sabin 2 virus. Here, we report the development of a simple quantitative one-step reverse-transcription polymerase chain reaction assay for the detection and quantitation of Sabin 2 virus in the presence of overwhelming amounts of nOPV2 strain. The method is specific and linear within 8 log₁₀ range even in the presence of relevant amounts of nOPV2 virus. It is sensitive, with a lower limit of detection of 0.2 CCID₅₀/mL (an equivalent of 198 genome copies per mL), and generates reproducible results. This assay can be used for quality control and lot release of the nOPV2.

Is contamination of bovine-sourced material with bovine viral diarrhea virus still a problem in countries with ongoing eradication campaigns?

In this report, we describe the detection of bovine viral diarrhea virus (BVDV) contamination in commercial animal-derived sera and vaccines against animal viral pathogens on the market in Poland. Antibodies against BVDV were detected in 4/45 sera samples (8.9%) using an ELISA test. The presence of BVDV antigen was found using ELISA in 3/45 serum samples (6.6%) and 18/172 vaccine samples (10.5%). An RT -PCR was conducted using primers targeting two genome regions, the five prime untranslated region (5’UTR) and N-terminal protease (Npro). BVDV RNA was detected in 33/45 (73.3%) of sera, and 11/172 samples (6.4%) of collected vaccines, of which one vaccine did not declare BVDV strain in its composition. A single serum showed the presence of an infectious virus and only one was contaminated with all 3 species of BVDV. The most frequent species in sera was BVDV-3 (75.5%), whereas in vaccines only BVDV-1 was identified. Sequence analysis showed that the tested commercial sera and one vaccine were contaminated by six genotypes of BVDV: -1a, -1b, -1c, -1d, -2a, and -3. Identification of BVDV and its genetic material in animal-derived products is important due to the possibility of pestivirus transmission as well as the chance of falsifying the results of a diagnostic test. It also demonstrates the necessity of rigorous monitoring of the bioproducts used at the laboratory and industry level.

Three-percent sucrose acts as a thermostabilizer for cell-adapted foot-and-mouth disease virus without any negative effect on viral growth

AIMS

As cell-adapted foot-and-mouth disease virus (FMDV) with H56R mutation in VP3 has reduced thermostability, this study aimed to investigate the effect of thermostabilizers on cell-adapted FMDV for vaccine production.

METHODS AND RESULTS

We examined the effect of 3% sucrose, 10% (or 25%) glycerol or 10% FBS on cell-adapted FMDV O/SKR/JC/2014, containing H56R mutation in VP3, as vaccine seed virus at -80, 4, 25 or 37°C for 2, 4 or 7 days. The stabilizing effect of 3% sucrose on O/SKR/JC/2014 was observed at 25, 37°C, and after repeated freeze-thaw cycles. Additionally, we tested the effect of 3% sucrose on the growth of FMDV or cells and did not observe any decrease in either viral growth or cell viability.

CONCLUSIONS

Our study showed the protective effect of 3% sucrose on FMDV infectivity at various temperatures; this virus stock in 3% sucrose could be used for infecting cells without the removal of sucrose.

SIGNIFICANCE AND IMPACT OF THE STUDY

We suggest that 3% sucrose-containing medium could be beneficial for the stable storage and transport of cell-adapted FMDV.

Molecular Characterization of Pestiviruses in Fetal Bovine Sera Originating From Argentina: Evidence of Circulation of HoBi-Like Viruses

Serological evidence suggests that HoBi-like viruses, an emerging species within the Pestivirus genus of the Flaviviridae family, are in circulation in Argentina. While HoBi-like viruses were first isolated from Brazilian fetal bovine serum (FBS), no survey of Argentine FBS has been conducted. Therefore, 124 local samples of non-irradiated FBS originating from Argentina were surveyed for the presence of pestiviruses using RT-PCR. Amplicons from pestivirus positive samples were genotyped. Four samples were positive for HoBi virus-specific RT-PCR, while the BVDV-positive samples (n = 45) were classified as BVDV-1b (82.2%), BVDV-1a (13.3%), and BVDV-2 (4.5%). Virus isolation and serological profile assessment were performed for the four HoBi-positive FBS lots. These results confirm the circulation of HoBi-like virus in some regions of the Argentinean territory, highlighting the need to review the diagnostic techniques currently used in the clinical cases suspected of BVDV and in contamination control protocols for adventitious agents in cells and biotechnological products.