The worldwide increase in the prevalence of acute coronavirus respiratory syndrome 2 (SARS-CoV-2) has led to the alarming milestone of 100 million reported cases. Among the main reasons for the growth in disease numbers are the emergence of new changes, particularly the UK variant, with greater infectivity compared to ancestral sex. However, a new introductory research paper, posted to the preprint server bioRxiv*, presenting data showing that the Covaxin vaccine candidate made in India successfully neutralizes this variant, preventing infection when challenged.
Variety of the UK
The RA variant is also known as the Variant of Concern (VOC) 202012/01, also known as line B.1.1.7 or 20B / 501Y.V1. It has risen rapidly as the proportion of new cases of COVID-19 in the UK in less than two months. B.1.1.7 has also been ordered from other countries, and with direct flights connecting many of these affected regions to and from the UK, it is clear that there is potential for a significant increase in issues around the world.
Similar concerns have been expressed about the so-called South African divergence, confirming the issues raised by these variables regarding the protection of recently available COVID-19 vaccines.
The RA variant has 17 mutations in its genome, with eight on the spike-binding domain (RBD), which allows the virus to bind to the angiotensin-converting enzyme receptor 2 (ACE2) on the target host cell.
The UK has introduced the Pfizer-BioNTech vaccine, and the Oxford Astra-Zeneca vaccine. Both are mRNA vaccines, stimulating spike antigen sensitization of earlier SARS-CoV-2 sequences. The million dollar question is whether the many spike mutations found in the later variants will affect the ability of vaccine-induced antibodies directed against the earlier spike version of D614G to neutralize the virus.
The vaccine
Covaxin is a full-virion native vaccine of SARS-CoV-2 BBV152. A high-strength clinical trial was reported in a phase I clinical trial against hCoV-19 / India / 2020770 homologous strain, as well as two other heterologous non-homogenous strain series, hCoV-19 / India / 2020Q111 and hCoV-19 / India / 2020Q100. Notably, the N501Y mutations of the RBD spike strain UK are in all three series.
Phase II trials showed impressive results with the plaque-neutralization test (PRNT50), with serum immunity from Covaxin recipients demonstrating the ability to reduce the level of viral infection of cells in culture at low titers after vaccination. Seroconversion and neutralizing antibody production occurred in 99.6% of subjects.
(A) Irregular antibody response of BBV152 / COVAXINTM vaccine sera against SARS CoV-2 strains: Neutral antibody titers (PRNT50) of vaccine sera against hCoV-19 / India / 2020770 (homologous), hCoV-19 / India / 20203522 (heterologous UK strain) and hCoV-19 / India / 2020Q111 (non-heterologous browser). The bar represents the geometric meaning and general orientation of the individual group titles. A non-parametric Kruskal-Wallis test was used to compare PRNT50 values from different groups. Values above 0 • 05 were considered unimportant and are marked on the figure (ns non-significant). (B) Comparison of PRNT50 value of sera per vaccine recipient with three strains of SARS CoV-2: Neutral antibody titers (PRNT50) of sera per vaccine against hCoV-19 / India / 2020770 (homologous), hCoV -19 / India / 20203522 (heterologous strain UK) and hCoV- 19 / India / 2020Q111 (non-heterologous strain). The bar represents the average and general deviation of the individual sera.
Study shows effectiveness against UK variables
The present study reports the results of a neutralization test of serum samples obtained from phase II test participants against the UK variant.
The researchers first differentiated the UK from the UK returnees in India. The holateo hCoV-19 / India / 20203522 exhibited all character mutations found in SARS-CoV-2 (VOC) 202012/01.
The sera from 38 BBV152 vaccine subjects have been tested against the UK variant. Meanwhile, sera from 20 subjects were tested against one of the unclassified heterologous strains listed above, hCoV-19 / India / 2020Q111.
The PRNT50 tests showed a mean ratio of neutralization efficiency of 0.8 and 0.9 when the homologous strain hCoV-19 / India / 2020770 was compared with the UK difference hCoV19 / India / 20203522 and the other heterologous strain hCoV-19 / India / 2020Q111, respectively.
In other words, the neutralizing antibodies obtained by vaccination with BBV152 / Covaxin were equally effective against both the homologous strain circulating to hCoV-19 / India / 2020770 and the UK variant hCoV-19 / India / 20203522. It was also effective in neutralizing another heterologous species, hCoV-19 / India / 2020Q111.
What is the impact?
Earlier studies have shown that the UK variant altered neutralization with convalescent plasma containing high titers of neutralizing antibodies. This was confirmed by the presence of E484 substitution coupled with subsequent 11-amino acid insertion in the NTD loop N5 of the spike antigen.
This caused much uncertainty as to whether the standard vaccines would neutralize the new variables. The current study alleviates these concerns by showing relatively neutral activity of individuals who received the vaccine against the homologous and heterologous strains of the virus. These findings indicate that the mutations in the UK variant do not mediate immune escape to neutralize antibodies derived from Covaxin vaccine.
Covaxin was released in India’s largest vaccination program in the world, along with the Indian-made Oxford Astra-Zeneca vaccine, distributed under the Covishield name. The researchers say, “A 501Y mutation is unlikely to be able to reduce the potential benefits of the vaccine.”
* Important message
bioRxiv publish preliminary scientific reports that are not peer-reviewed and, therefore, should not be seen as final, guiding health-related clinical practice / behavior, or be treated as information established.