Coronavirus disease 2019 (COVID-19), which occurs through severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, has already claimed more than 6. 8 million lives worldwide. Despite the immediate progression and widespread distribution of COVID-19 vaccines, the pandemic persists due to the continued emergence of new variants of SARS-CoV-2.
Some of these variants, such as Delta and Omicron fear variants (VOCs), may evade the immune reaction induced by vaccination or herbal infection. Therefore, scientists are looking for existing vaccine formulations to provide greater coverage against SARS-CoV. -2 infection.
Most COVID-19 vaccines target the spike protein of the ancestral strain of SARS-CoV-2. Due to the presence of mutations in SARS-CoV-2 variant spike proteins, the efficacy of these vaccines has been particularly reduced.
SARS-CoV-2 will have to triumph over the anatomical and immunological barriers that occur through the nasal mucosa to identify the infection. Mucosal immunity plays a very important role in blocking SARS-CoV-2 infection to save you from transmission; However, all newly available intramuscular COVID-19 vaccines primarily cause systemic immunity, with limited effect on mucosal immunity.
An effective intranasal vaccine can be incredibly helpful in controlling the COVID-19 pandemic by generating protective mucosal immunity at the site of infection and systemic immunity. Recently, Bharat Biotech International Limited (BBIL) in India developed BBV154. Intranasal SARS-CoV-2 vaccine encoding a wild-type SARS-CoV-2 spike protein stabilized by prefusion with two proline substitutions in the S2 subunit.
Preclinical animal studies in mice, hamsters, rabbits and rats revealed that BBV154 induces systemic immune responses and humoral and cell-mediated mucous membranes.
In fact, a single intranasal dose of BBV154 elicited an impressive immune reaction in transgenic K18-hACE2 99 mice highly vulnerable to the same doses of intramuscular COVID-19 vaccines. In addition, a single intranasal dose of BBV154 in Syrian golden hamsters, K18- transgenic hACE2 mice and rhesus macaques prevented the progression of upper and lower respiratory tract infections and inflammations due to COVID-19.
A recent preliminary study published by The Lancet looks at the protection profiles and immunogenicity of BBV154 in healthy adults. These effects are based on the effects of a phase III, randomized, controlled, open-label clinical trial conducted in hospitals in India.
The authors evaluated the safety, tolerability, and immunogenicity of BBV154 in healthy adults, including non-pregnant men and women, and the efficacy of this vaccine with the licensed intramuscular vaccine, Covaxin.
All test participants were between 18 and 60 years old at the time of recruitment. None of the test participants had won a COVID-19 vaccine in the past or had a history of SARS-CoV-2 infection.
A total of 3209 participants were enrolled between April 16, 2022 and June 2022, of whom 2998 were randomized to BBV15 and 162 to obtain Covaxin.
The neutralization titers against the ancestral SARS-CoV-2 strain induced after two weeks of receiving the dose of the BBV154 intranasal vaccine were particularly superior to those produced in the Covaxin recipients under conditions.
Neutralizing antibodies were also detected 3 months after the first dose of BBV154, confirming its durability. The intranasal vaccine also caused an accumulation of cross-neutralization titers opposed to the BA. 5 sublineage of the Omicron variant.
Robust mucosal antibodies in the form of secretory immunoglobulin A (sIgA) were also detected in participants who won BBV154 on day 42. The levels of sIgA in the BBV154 organization were particularly higher than those in the Covaxin organization. This validated localization was based on the presence of statistically significant IgA-secreting plasmablasts in the BBV154 organization at day 42 compared to day 0.
Both COVID-19 vaccines were well tolerated with low reactogenicity rates. None of the participants reported serious adverse events after vaccination.
For respiratory infections, mucosal immunization is related to several traditional intramuscular vaccines. For example, mucous membrane IgA protects mucosal surfaces from respiratory viruses by inhibiting their binding to epithelial cells. Previous studies on influenza infection have found that influenza-specific IgA is more effective in preventing human infection than influenza-specific IgG.
SARS-CoV-2, first of all, infects the upper respiratory tract, resulting in higher plasma levels of IgA antibodies that bind to the virus and prevent infection. This highlights the very important role of IgA-mediated mucosal immunity against COVID-19.
IgA dimers discovered in the nasopharynx are particularly more potent than IgA monomers against the same target. Therefore, secretory IgA (dimers) may be more effective in protecting against SARS-CoV-2 infection.
The intranasal vaccine BBV154 was found to be superior to the intramuscular vaccine Covaxin because BBV154 induces higher levels of plasmablasts secreting IgG/IgA that correlate with a greater neutralizing force against homologous and heterologous SARS-CoV-2 strains.
Some of the key benefits of BBV154 are non-invasion, ease of administration, improved patient adherence and suitability for mass vaccination. Currently, further clinical progression of BBV154 is underway as a component of a heterologous booster vaccination regimen.
Written by
Priyom holds a PhD in Plant Biology and Biotechnology from the University of Madras, India. She is an active and experienced science writer. Priyom also co-authored several original articles that have been published in reputable peer-reviewed journals. He is also an avid reader and amateur photographer.
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