Omicron (B.1.1.529) - variant of concern - molecular profile and epidemiology: a mini review.

Recently a new variant of SARS-CoV-2 was reported from South Africa. World Health Organization (WHO) named this mutant as a variant of concern - Omicron (B.1.1.529) on 26th November 2021. This variant exhibited more than thirty amino acid mutations in the spike protein. This mutation rate is exceeding the other variants by approximately 5-11 times in the receptor-binding motif of the spike protein. Omicron (B.1.1.529) variant might have enhanced transmissibility and immune evasion. This new variant can reinfect individuals previously infected with other SARS-CoV-2 variants. Scientists expressed their concern about the efficacy of already existing COVID-19 vaccines against Omicron (B.1.1.529) infections. Some of the crucial mutations that are detected in the receptor-binding domain of the Omicron variant have been shared by previously evolved SARS-CoV-2 variants. Based on the Omicron mutation profile in the receptor-binding domain and motif, it might have collectively enhanced or intermediary infectivity relative to its previous variants. Due to extensive mutations in the spike protein, the Omicron variant might evade the immunity in the vaccinated individuals.

Evolving biothreat of variant SARS-CoV-2 - molecular properties, virulence and epidemiology.

SARS-CoV-2 are enveloped RNA viruses that belong to the family Coronaviridae of genus Beta coronavirus, responsible for the COVID-19 pandemic. The mutation rate is high among RNA viruses and in particular, coronavirus replication is error prone with an estimated mutation rate of 4x10-4 nucleotide substitutions per site per year. Variants of SARS-CoV-2 have been reported from various countries like United Kingdom, South Africa, Denmark, Brazil and India. These variants evolved due to mutations in spike gene of SARS-CoV-2. The most concerning variants are Variant of Concern (VOC) 202012/01 from United Kingdom and B.1.617 variant of India. Other variants include B.1.351 lineages, cluster 5/SARS-CoV-2 variant of Denmark, 501.V2 variant/SARS-CoV-2 variant of South Africa, lineage B.1.1.248/lineage P.1 of Brazil. Mutations in S protein may result in changes in the transmissibility and virulence of SARS-CoV-2. To date, alterations in virulence or pathogenicity have been reported among the variants from many parts of the globe. In our opinion, since the S protein is significantly altered, the suitability of existing vaccine specifically targeting the S protein of SARS-CoV-2 variants is a major concern. The mutations in SARS-CoV-2 are a continuous and evolving process that may result in the transformation of naïve SARS-CoV-2 into totally new subsets of antigenically different SARS-CoV-2 viruses over a period of time.

COVID-19 (Novel Coronavirus 2019) - recent trends.

The World Health Organization (WHO) has issued a warning that, although the 2019 novel coronavirus (COVID-19) from Wuhan City (China), is not pandemic, it should be contained to prevent the global spread. The COVID-19 virus was known earlier as 2019-nCoV. As of 12 February 2020, WHO reported 45,171 cases and 1115 deaths related to COVID-19. COVID-19 is similar to Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) virus in its pathogenicity, clinical spectrum, and epidemiology. Comparison of the genome sequences of COVID-19, SARS-CoV, and Middle East Respiratory Syndrome coronavirus (MERS-CoV) showed that COVID-19 has a better sequence identity with SARS-CoV compared to MERS CoV. However, the amino acid sequence of COVID-19 differs from other coronaviruses specifically in the regions of 1ab polyprotein and surface glycoprotein or S-protein. Although several animals have been speculated to be a reservoir for COVID-19, no animal reservoir has been already confirmed. COVID-19 causes COVID-19 disease that has similar symptoms as SARS-CoV. Studies suggest that the human receptor for COVID-19 may be angiotensin-converting enzyme 2 (ACE2) receptor similar to that of SARS-CoV. The nucleocapsid (N) protein of COVID-19 has nearly 90% amino acid sequence identity with SARS-CoV. The N protein antibodies of SARS-CoV may cross react with COVID-19 but may not provide cross-immunity. In a similar fashion to SARS-CoV, the N protein of COVID-19 may play an important role in suppressing the RNA interference (RNAi) to overcome the host defense. This mini-review aims at investigating the most recent trend of COVID-19.