Testing the genomic stability of the Brazilian yellow fever vaccine strain using next-generation sequencing data

Genome stability assessment of PRRS vaccine strain with new ARTIC-style sequencing protocol

A tiling amplicon sequencing protocol was developed to analyse the genome sequence stability of the modified live PRRSV vaccine strain, Porcilis MLV. The backbone of the ARTIC-style protocol was formed by 34 individual primer pairs, which were divided into two primer pools. Primer pairs were designed to amplify 532 to 588 bp fragments of the corresponding genomic region. The amplicons are suitable for sequencing on Illumina DNA sequencers with available 600-cycle sequencing kits. The concentration of primer pairs in the pools was optimized to obtain a balanced sequencing depth along the genome. Deep sequencing data of three vaccine batches were also analysed. All three vaccine batches were very similar to each other, although they also showed single nucleotide variations (SNVs) affecting less than 1 % of the genome. In the three vaccine strains, 113 to 122 SNV sites were identified; at these sites, the minority variants represented a frequency range of 1 to 48.7 percent. Additionally, the strains within the batches contained well-known length polymorphisms; the genomes of these minority deletion mutants were 135 to 222 bp shorter than the variant with the complete genome. Our results show the usefulness of ARTIC-style protocols in the evaluation of the genomic stability of PRRS MLV strains.

A Review of the Establishment of the Seed Lot System in the Production of Biological Products and Its Importance

Today, due to the importance of diseases controlled by vaccination, the production of biological products is of great importance in ensuring public health, so producing high-quality biological products plays an important role in maintaining public health. One of the most important principles of manufacturing high-quality and efficient biological products is using suitable seeds based on standard principles. To produce a suitable seed for continuous use for mass production of biological products, the seed must be defined according to certain principles and foundations. These principles are formed in the form of a seed lot system. In this review article, all the requirements for the establishment of a seed to produce a biological product include general seed information, including basic and seed information and microorganisms, seed-specific information including seed passage levels, propagation method, seed storage conditions, coding and labeling, identification information and design of suitable laboratories for passage, seed propagation, and storage, determination of seed characteristics including all necessary tests to determine seed identity, purity, potency, efficacy, stability, safety and also all the necessary information for documenting and storing seeds has been studied. Also, this study discusses the method of preparing all the necessary information for establishing a seed lot system, especially determining the characteristics of seeds. Based on the study's results, a complete and comprehensive seed lot system has been formed that can be used to prepare, propagate, passage, and store seeds used in the production of biological products.

The Present and Future of Yellow Fever Vaccines

The disease yellow fever (YF) is prevented by a live-attenuated vaccine, termed 17D, which has been in use since the 1930s. One dose of the vaccine is thought to give lifelong (35+ years) protective immunity, and neutralizing antibodies are the correlate of protection. Despite being a vaccine-preventable disease, YF remains a major public health burden, causing an estimated 109,000 severe infections and 51,000 deaths annually. There are issues of supply and demand for the vaccine, and outbreaks in 2016 and 2018 resulted in fractional dosing of the vaccine to meet demand. The World Health Organization (WHO) has established the “Eliminate Yellow Fever Epidemics” (EYE) initiative to reduce the burden of YF over the next 10 years. As with most vaccines, the WHO has recommendations to assure the quality, safety, and efficacy of the YF vaccine. These require the use of live 17D vaccine only produced in embryonated chicken eggs, and safety evaluated in non-human primates only. Thus, any second-generation vaccines would require modification of WHO recommendations if they were to be used in endemic countries. There are multiple second-generation YF vaccine candidates in various stages of development that must be shown to be non-inferior to the current 17D vaccine in terms of safety and immunogenicity to progress through clinical trials to potential licensing. The historic 17D vaccine continues to shape the global vaccine landscape in its use in the generation of multiple licensed recombinant chimeric live vaccines and vaccine candidates, in which its structural protein genes are replaced with those of other viruses, such as dengue and Japanese encephalitis. There is no doubt that the YF 17D live-attenuated vaccine will continue to play a role in the development of new vaccines for YF, as well as potentially for many other pathogens.

Bioinformatics in Latin America: ISCB-LA SOIBIO RMB Symposium 2020

This special issue ‘Bioinformatics in Latin America: ISCB-LA SOIBIO RMB Symposium 2020’ features the papers presented at the ISCB-LA SoIBio BioNetMX 2020 Virtual Symposium held on 28–29 October 2020. This is the first international joint event organized by the Mexican Network for Bioinformatics (RMB), the International Society of Computational Biology (ISCB) and the Iberoamerican Society for Bioinformatics (SOIBIO). The aim of this event is to foster interdisciplinary and multidisciplinary collaborations in research across Exact and Life Sciences.