** Islami Jubo Khelafat Bangladesh stages a demonstration in front of Baitul Mukarram National Mosque in the capital on Friday to protest the burning of the Holy Quran in Sweden and the Israeli aggression against Palestinian Muslims. ** Shoppers in thousands throng the Dhaka International Trade Fair (DITF) at newly inaugurated Bangabandhu Bangladesh-China Friendship Exhibition Centre at Purbachal on Friday. ** 18 years of Kibria murder Trial deferred repeatedly due to lack of witnesses ** Gas supply shortage hits households, industries ** Production remains halted in 8 Ctg power plants ** Israeli violence BD condemns killing of ten Palestinians ** HC-order to ban single-use plastic items ** 532 students commit suicide in 2022 ** ‘Work of Rooppur Nuclear Power Plant will not be stopped’ ** Protests against Quran burning held across Middle East ** More delay in change will lead to more miseries for people ** Chaos between bench and bar ** Workers busy preparing stalls for the month-long Amar Ekushey Boi Mela, which is scheduled to begin on the Bangla Academy premises and part of Suhrawardy Udyan in the capital from February 1. NN photo ** USAID announces additional $75m assistance for Rohingyas ** Sugar price rises by Tk 5 per kg ** Germany, US, to send battle tanks to help Ukraine fight off Russia ** Israel army kills nine Palestinians ** DCs confce ends with numbers of directives by govt ** ACC files another case against Mannan, 11 others ** Raju arrested over Ekushey Padak journo murder case ** DCs asked to stop illegal sand lifting from rivers ** Refusal of bail and deaths in police custody must be taken as violation of constitutional rights against torture and right to life ** Hike gas prices in phases: BGMEA ** Presidential election scheduled for Feb 19 ** ‘Distorted history in textbooks to lead the nation to destruction’ **

Hopeful RNA vaccine strategies in Covid-19 pandemic

12 July 2020
Hopeful RNA vaccine strategies in Covid-19 pandemic

Dr. Muhammad Torequl Islam :
An injection of nucleic acids (e.g., RNA or DNA) into the experimental animals (e.g., mice) lead to the expression of some proteins encoded by the injected nucleic acid, suggesting a gene encoding a protein of a pathogen is necessary to create a vaccine. Both DNA and RNA vaccines induce immune responses. Delivery through plasmid (a small, circular extrachromosomal DNA molecule) can be incorporated to develop vaccines against severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2).
Beside this, much interest has been grown on messenger RNA (mRNA) vaccinology due to the mRNA stability, protein production capability and improved delivery facilities. In the latter case, modified nucleosides and nanocarrier-mediated delivery technologies can be used to stabilize mRNA molecules, enhance cellular uptake, avoid the risk of integration into the host genome, and improve the bioavailability of the mRNA molecules inside the host cells. Moreover, mRNA molecules do not need to enter the nucleus to express the antigen, unlike DNA vaccines. A DNA vaccine, once inside the nucleus is capable to produce many copies of mRNA, which results mass production antigens per transfected cell. Therefore, we can think about self-amplifying RNA vaccines to increase the yield of antigen expression per transfected host cell. The self-amplifying RNA vaccines derived from the genome backbone of an alpha-virus can be delivered in the form of plasmid DNA, virus-like RNA particles, and in vitro transcribed RNA, that may elicit stronger immune responses than the mRNA vaccines.
Two RNA vectors dependent strategy (i.e., one retaining the replicase-encoding gene, while other encoding the antigen) can be also developed. In this case, the replicase machinery is provided "in trans" (i.e., two genes acting together, but on different RNAs) by a self-amplifying RNA or a non-replicating mRNA; mediates replication of the antigen-encoding RNA. Compared to the self-amplifying RNA technology, this strategy has more safety, manufacturability, and ease of optimization. The use of two separate RNAs avoids the risk incurred with self-amplifying RNAs that are engineered to express budding-competent viral glycoproteins that could, in theory, find their way into extracellular vesicles and transfer to new host cells. The trans-amplifying approach permits shorter lengths of RNA, which is a major challenge in self-amplifying RNA vaccine technology. Moreover, this strategy can be improved by implementing new mRNA strategies, including modification of nucleosides, sequence stabilization, and codon optimization of the entire replicon gene that are the other potential challenges for the self-amplifying RNA technology.

An mRNA vaccine was the first undergone clinical trials, immediately after the genetic sequence of SARS-CoV-2 was released. Currently, nucleic acid vaccines are one of the major hopes for SARS-CoV-2 infection as it requires only the sequence of a pathogen to generate the vaccine. Simplicity, manufacturability, ease to delivery, and rapid response are the noticeable advantages of this vaccine technology. However, practically the ability of all kinds of vaccines will confirm the reliabiliy, effectivity, and safety of a particular vaccine for this pandemic outbreak once we get at our hands. Right now, we can only hope that their deployment will render the novel coronavirus disease 2019 (Covid-19) pandemic crisis to a manageable challenge, saving lives, thereby, decreasing the morbidity.

(Dr. Muhammad Torequl Islam is Assistant Professor, Department of Pharmacy, Life Science Faculty, Bangabandhu Sheikh Mujibur Rahman Science and Technology University. E-mail: [email protected])

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