STTT:BA.5 causes stronger damage to cardiomyocytes than BA.1, similar to Delta

The new coronavirus, which usually infects humans through the respiratory tract, causes damage
to the respiratory system and various organs of the human body.
Since the first outbreak at the end of 2019, the new coronavirus has still ravaged the world, causing a great negative impact
on the world economy and society.

A number of studies have shown that the new crown is not only a respiratory disease, but affects many tissues and organs of the human body, including the gastrointestinal tract, cardiovascular and nervous system
.

Myocarditis, that is, inflammation of the myocardial layer of the heart wall, is usually caused by a viral infection or an immune response after a viral infection, including influenza virus, adenovirus, cytomegalovirus, new coronavirus, etc
.
After the virus invades the body, it can replicate and destroy cardiomyocytes within the heart muscle while activating the immune and inflammatory responses
in the body.

Researchers from the University of Ulm in Germany published an article titled "Strong attenuation of SARS-CoV-2 Omicron BA.
1 and increased replication of the BA.
5 subvariant in human cardiomyocytes" in the journal "Signal Transduction and Targeted Therapy" Research papers
.

The study found through in vitro cell studies that the Delta variant has much stronger replication ability and destructive power in cardiomyocytes than the BA.
1 variant, and BA.
2, especially the BA.
5 variant, has a stronger replication ability and damage ability in cardiomyocytes than BA.
1, similar to the Delta variant
.

It is worth noting that this is an in vitro study, and whether this is the case in humans has yet to be verified
.

Early studies have shown that cardiomyocytes highly express the new coronavirus receptor ACE2, which is a key receptor for the new coronavirus to enter human cells, and the virus can be highly replicated
in cardiomyocytes.

In the study, the researchers tested the replicating ability of the original strain, Delta, Omicron BA.
1, BA.
2 and BA.
5 through cardiomyocytes cultured in vitro
.

The study found that from the perspective of viral replication, different new crown variants can infect cardiomyocytes, virus production usually reaches a maximum about 5 days after infection, compared with BA.
1, the original strain and Delta have stronger replication ability, and the infectious virion produced is about 2-3 orders of magnitude
higher.

For toxicity, Delta has a stronger cytopathic effect
than the original strain and BA.
1.
By microscopic observation, on the third day of infection, cardiomyocytes infected with the original strain and Delta lost the troponin T-positive sarcomere structure, while the cardiomyocytes infected with BA.
1 also maintained a well-organized sarcomere structure
.

Replication and toxicity of different viruses in human cardiomyocytes

Measurements of cardiomyocytes showed that the rate of beating of uninfected cardiomyocytes steadily decreased from 30 to 10 beats every 30 seconds over 10 days, while cardiomyocytes infected with the original strain or Delta usually stopped beating
completely on days 3-5.
In contrast, cardiomyocytes infected with BA.
1 had a delay
in stopping beats.

Further studies have found that the induction of inflammatory cytokines plays a key role
in the pathogenesis of the new crown.
After 4 days of infection, the levels of interferon and pro-inflammatory cytokines induced by the original strain and Delta were higher than BA.
1, further explaining the weaker
pathogenicity of BA.
1.

Replicating ability and toxicity of BA1, BA2, BA5

Finally, the study also found that compared to BA.
1, the BA.
5 variant is more replicable, produces a more contagious virus, can cause stronger cytopathic effects, and stops heart muscle cells beating faster, or similar
to Delta.
BA.
2 seems to be somewhere between
BA.
1 and BA.
5.

In summary, this in vitro cell study showed that BA.
1 has weakened replication and cytopathic effects in human cardiomyocytes compared to the original strain and Delta, while BA.
2, especially BA.
5, exhibits a higher replication rate than BA.
1 and leads to stronger cytopathic effects, showing more similar characteristics
to Delta.