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A vaccine designed to produce immunity against the more stable part of coronaviruses has been shown to neutralize viruses in mice. If the work can be transposed to humans – which the researchers admit to be quite distant – it could give us insurance against the next member of the viral family to switch from animals to humans, even though it’s considerably worse than COVID-19 .
After the initial SARS outbreak in the early 2000s, virologists realized it was only a matter of time before we encountered something much more difficult to combat. Since we couldn’t know the details of what we would be up against, the only option was to find a way to vaccinate against a feature common to all coronaviruses, similar to the quest for a universal flu vaccine.
Although several teams have moved in this direction, the donors did not grasp the urgency and the work progressed slowly or stopped for lack of support. Now that things look different, a team from Osaka University has now announced a big step forward in the Journal of Experimental Medicine.
“Since past outbreaks of coronaviruses such as SARS-CoV-1 and MERS-CoV have occurred due to zoonotic coronaviruses crossing the species barrier, the potential for the emergence of similar viruses in the future is a significant threat to global public health, even in the face of effective vaccines against current viruses. Professor Tomohiro Kurosaki said in a statement.
COVID-19 vaccines target the crucial “peak” protein that the virus uses to enter human cells. However, the tip actually consists of two parts: a “core” and a “head”. The nucleus is largely unchanged in all of the coronaviruses that have been studied, while the tip head differs in SARS-CoV-2 compared to other coronaviruses. Worse yet, the head has changed enough between the different variants of COVID-19 to undermine the effectiveness of vaccines designed against the original strain against new variants, although so far not as much as anti-vaccines like it. claim.
A vaccine that produces antibodies to the nucleus could protect against all strains of COVID-19, the original SARS if it returned and MERS which recurs periodically. Hopefully that would work against everything that comes next as well.
However, it is not an easy task. The immune system is so busy responding to the peak head that few antibodies to the nucleus are produced by existing vaccines. Kurosaki sought to get around this problem by producing SARS-CoV-2 proteins whose heads are covered with sugar molecules, thereby reducing the threat to the immune system.
When Kurosaki immunized mice with these sugar-coated spike vaccines, they produced many more antibodies targeting the heart. When the same mice were exposed to SARS-CoV-2, these antibodies still did a good job of preventing the virus from entering their cells.
More importantly, these mice had also acquired partial immunity to SARS-CoV-1 and three coronaviruses that infect bats and pangolins but have not (yet) affected humans.
“Our data suggests that modified versions of the advanced receptor binding domain could be a useful element for the development of next-generation vaccines that are broadly protective to prevent future coronavirus pandemics,” Kurosaki said.
Other teams are also chasing the dream of broad-spectrum coronavirus vaccines, with clinical trials underway for a vaccine that could protect at least against those most closely related to each other.
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