SARS-CoV-2 Gamma variant

The Gamma variant (P.1) was one of the variants of SARS-CoV-2, the virus that causes COVID-19. This variant of SARS-CoV-2 has been named lineage P.1 and has 17 amino acid substitutions, ten of which in its spike protein, including these three designated to be of particular concern: N501Y, E484K and K417T. It was first detected by the National Institute of Infectious Diseases (NIID) of Japan, on 6 January 2021 in four people who had arrived in Tokyo having visited Amazonas, Brazil, four days earlier. It was subsequently declared to be in circulation in Brazil. Under the simplified naming scheme proposed by the World Health Organization, P.1 was labeled Gamma variant, and was considered a variant of concern until March 2022, when it was largely displaced by the delta and omicron variants.

Gamma caused widespread infection in early 2021 in the city of Manaus, the capital of Amazonas, although the city had already experienced widespread infection in May 2020, with a study indicating high seroprevalence of antibodies for SARS-CoV-2. A research article published in Science Journal indicate that P.1 infected people have a greater chance of transmissibility and death than B.1.1.28 infected ones.

The Gamma variant comprises the two distinct subvariants 28-AM-1 and 28-AM-2, which both carry the K417T, E484K, N501Y mutations, and which both developed independently of each other within the same Brazilian Amazonas region.

Gamma is notably different from the Zeta variant (lineage P.2) which also circulated strongly in Brazil. In particular, Zeta only carries the E484K mutation and has neither of the other two mutations of concern, N501Y and K417T.

Initial reports claimed that both P.1 and P.2 were two separate and different descendants of the Brazilian lineage B.1.1.248. However, B.1.1.248 later lost its status as a distinct lineage and was reclassified to B.1.1.28. P.1 has also been called B.1.1.28.1, while P.2 has been B.1.1.28.2 or VUI-202101/01. Since only three sublevels are permitted in the PANGO Lineage system of nomenclature, hence the designation of B.1.1.28.1 to P.1 and B.1.1.28.2 to P.2.

Following its detection, genome data for four samples of the new variant were shared to GISAID having been assigned the ID range: EPI_ISL_792680 to EPI_ISL_792683.

Variants of SARS-CoV-2

As well as having eight mutations (four of these synonymous genetic mutations) in its open reading frames (ORF1a and ORF1b) – one of which is a set of deletions – Gamma has 10 defining mutations in its spike protein, including N501Y and E484K. It also has two mutations – one an insertion – in its ORF8 gene and one in its N gene.