engleski

Genetic diversity of SARS-CoV-2 in Croatia

SARS-CoV-2 as an RNA virus with a large genome is subject to rapid mutation as it replicates. Among silent or deleterious mutations are the one that creates variants with a selective advantage. In late 2020 and early 2021 emerged variants that appear to be more transmissible than existing strains, evade immunologic response and induce more severe disease. Three variants that rapidly became dominant in specific area and were designated variant of concern (VOC) are: VOC- 202012/01 (B.1.1.7), 501Y.V2 (B.1.351) and P.1 (B.1.1.28.1). To this date GISAID acknowledges two more VOCs: GH/452R.V1 (B.1.429+B.1.427) and G/484K.V3 (B.1.525). To monitor the epidemiologic situation we followed ECDC recommendation and conduct whole-genome sequencing (WGS) on 5-10% SARS-CoV-2 positive samples in Croatia. WGS is performed weekly from 09.02.2021. Obtained sequences are uploaded to GISAID database and isolates are categorized in phylogenetic clades depending on single nucleotide polymorphism (SNP) present in the genome. By the end of March 2021 we processed 2632 samples. 1901 samples were successfully sequenced. Between the second and third waves of the epidemic, virus lineages from clade G, GR and GV were dominant, but marked weekly increase of GRY clade indicated the beginning of the third epidemic wave in Croatia. Delivered results showed marked continuous increase in B.1.1.7 presence from 21.23% in the first week of testing, to 94.27% in the last week of March. Variant B.1.351 from GH clade was detected in 15 samples, mainly related to travelling abroad and their close contacts. B.1.526 detected in 4 samples carry mutation essential for the loss of neutralizing activity of some monoclonal antibodies and is considered variant of interest.

SARS-CoV-2 ; variants ; epidemiology ; Croatia

nije evidentirano