SARS-CoV-2 variants occur when there are changes or “mutations” in the original virus’ genetic code. These changes occur naturally over time as a by-product of replication.
For example, the B.1.1.7 variant was first identified in the United Kingdom where the mutation occurred on the receptor binding domain (RBD) of the spike protein at protein 501, and the amino acid asparagine (N) was replaced with tyrosine (Y).
Other variants have been identified, including the B.1.351 lineage that originated in South Africa and the P.1 lineage that originated in Brazil and Japan.
The SARS-CoV-2 variants are of concern because they appear to spread much faster and may impact the effectiveness of vaccines and therapeutics (medicines to help cure and soothe COVID-19 patients).
Figure 1.1. Rapidly spreading variants are being observed globally. Some mutations confer potential selective advantages to the virus, such as increased transmissibility or immune evasion. Photo Credit: Mariana Bego.
Figure 1.2. Rapidly spreading variants are being observed globally. Some mutations confer potential selective advantages to the virus, such as increased transmissibility or immune evasion. Photo credit: Mariana Bego.
Figure 1.3. When a person is infected with the virus such as SARS-CoV-2, the virus replicates many times in the host (humans). These viruses can be passed on from person to person through respiratory droplets (sneezing and coughing). With rapid virus replication and immune pressure to control the virus, this can cause the virus to mutate, generating a new variant. If the mutation found in the variant confers it some advantage, it will spread better in the population. Photo credit: Mariana Bego.