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iNature
In November 2021, Omicron (B.
1.
1.
529) of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) was first detected in South Africa and Botswana Variants
.
The first Omicron sublineage to emerge was BA.
1, which was replaced
by BA.
2 in many countries.
One of the most striking features of the Omicron variant is its ability to evade neutralizing antibodies (nAbs) against the original virus line, due to new mutations embellished in the spike protein.
Especially in receptor-binding domains (RBDs) and N-terminal domains.
Therefore, the immune response generated by the use of Omicron in people who have already been vaccinated is worth paying attention to
.
However, until now, little is known that the Omicron/BA.
2 variant interacts with vaccine-induced immunity to influence infection
.
On January 6, 2023, He Yaqing of the Shenzhen Center for Disease Control and Prevention, Zhang Hui of Sun Yat-sen Medical College of Sun Yat-sen University and Liu Bingfeng collaborated on Signal
The journal Transduction and Targeted Therapy published online titled "Antibody.
"
response and cross-neutralization after Omicron BA.
2 infection", which explores the effects of BA.
2 on the Omicron subfamily BA.
2.
12.
1, BA.
4 and BA.
5 infection-induced immunity and vaccine-induced immunity
.
In addition, based on immunity to BA.
2 infection by inactivated vaccines, the immune evasion capacity of the emerging SARS-CoV-2 Omicron subline was systematically evaluated.
2 cases
by genome sequencing from the Centers for Disease Control (CDC, Shenzhen).
Of these, 14 received the coronavirus vaccine before contracting BA.
2 and 13 received the third dose ( Booster dose), 4 people were not vaccinated and infected with BA.
2
.
A serum sample
is collected within 3 days of diagnosis.
To study early humoral immune responses, specific antibody titers were first measured and cross-reactivity
was detected.
Consistent with previous reports on Omicron's enhanced immune evasion capacity, early antibody responses favored the ancestral SARS-CoV-2 strain In addition, the booster dose of the vaccine (third dose) resulted The IgG titer was significantly increased, not only significantly binding to BA.
2 spike protein, but also having a high affinity
for D614G and Delta spike protein.
In addition, after processing pseudotypic virus test results, it was found that individuals who received 2 or 3 doses of the vaccine had significantly stronger nAbs
.
Meanwhile, only one of the four unvaccinated volunteers had detectable levels of nAbs, compared with 8 and 13 of the 14 volunteers in the fully vaccinated and enhanced groups Ten of the volunteers each showed significant neutralization ability
.
These results suggest that the third dose (booster) vaccine provides better protection
against BA.
2 in the early stages.
The researchers further recruited 43 volunteers and divided them into three groups:(a) BA.
2 infected people and those who received (b) before BA.
2 breakthrough infection People with two doses or (c) three doses of inactivated virus vaccine.
All cases were confirmed by Shenzhen CDC sequencing and serum
was collected 28 days after the first PCR diagnosis.
First, the neutralization ability
of serum samples BA.
2 from vaccinated and unvaccinated groups was compared.
As hypothetically, samples obtained from the uninoculated group have neutralizing activity
with low nAb titers.
In the inoculation group, BA.
2nAbs increased more than 15-fold, independent
of enhanced status.
Regarding neutralizing potency for all Omicron sublines, the lowest activity was against BA.
4/5, followed by higher activity against BA.
2.
12.
1, with the use of two doses of BA.
2 Compared with the cohort of breakthrough vaccines, it was 2.
9-fold and 2.
6-fold
lower, respectively.
Of note, serum from individuals who received three doses of coronavirus prior to BA.
2 breakthrough infection did not show significant impaired potency in BA.
4/5 and BA.
2.
12.
1 pseudoviral tests
。 In addition, the study explored serum for the effects of previously concerned variants of concern, VOCs), including Beta and Delta strains
.
The results showed that, unlike the unvaccinated group, the antibody response was heavily biased towards the Omicron strain/subline in the unvaccinated group, and the inoculated group showed considerable neutralizing ability, protecting the host from D614, Beta and Delta strain infection, which indicates the effectiveness and importance
of memory humoral immunity conferred by previous vaccination.
Omicron BA.
2 antibody response and cross-neutralization reaction after infection (picture from Signal Transduction and Targeted Therapy) is worth noting and confrontation Compared to Beta, nAb titers against Delta were significantly reduced, 5.
7-fold and 6.
25-fold lower than BA.
2 nAb titers, respectively times, while with BA.
2 Compared with nAb titers, nAb anti-Beta titers were reduced by 2.
7 times and 3.
8 times
, respectively.
Suggests that emerging BA.
2.
12.
1 and BA.
4/5 strains have a significant ability to evade previous immunity and may cause reinfection
.
In summary, this study found in BA.
2 Early stages of breakthrough infection, additional (third shot) vaccine booster doses result in higher anti-spike IgG and nAb
titers.
The study data suggest that in the case of BA.
2 breakthrough infection, previous vaccinations can produce a stronger humoral immune response with a broader neutralizing response
to VOCs and Omicron sublineages.
Furthermore, mutations at the residue 452 site are one of the key drivers of the resistance phenotype, with BA.
2.
12.
1 and BA.
4/5 being more resistant than other strains
.
Because L452R is also a defining mutation of the Delta variant, the study observed that the new Omicron sublineage, containing the 452 mutation, neutralized more effectively Delta convalescent serum
.
These results provide insights into understanding the role of pre-existing humoral immunity when exposed to exogenous SARS-CoV-2 variants.
The continued evolution of Omicron poses a significant challenge
to ancestral SARS-CoV-2 vaccine-induced or BA.
1/BA.
2 infection-induced herd immunity.
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The content is [iNature]
