Genomic Diversity and Evolution of SARS-CoV-2 Lineages in Pakistan

The emergence of SARS-CoV-2 variants has posed a challenge to disease control efforts worldwide. This study explored the genomic diversity and phylogenetic relationship of SARS-CoV-2 variants reported in Pakistan. Our objective was to understand the transmission dynamics of different lineages within the country. We retrieved and analyzed spike protein sequences from Pakistan and compared them with reference sequences reported worldwide. Our analysis revealed the clustering of Pakistan-origin isolates in nine different clades representing different regions worldwide, suggesting the transmission of multiple lineages within the country. We found 96 PANGO lineages of SARS-CoV-2 in Pakistan, and 64 of these corresponded to 4 WHO-designated variants: Alpha, Beta, Delta, and Omicron. The most dominant variants in Pakistan were Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2, AY.108), and Omicron (BA.2.75, BA.5.2), and the N-terminal domain and receptor binding regions were the most hypervariable regions of the spike gene. Compared to the reference strain, characteristic substitutions were found in dominant variants. Our findings emphasize the importance of continuously monitoring and assessing nucleotide and residue substitutions over time to understand virus evolutionary trends better and devise effective disease control interventions.