Whole-genome sequencing of Crimean-Congo hemorrhagic fever virus circulating in Pakistan during 2022.

ABSTRACT

Pakistan is an endemic country for Crimean-Congo hemorrhagic fever (CCHF) and its Balochistan province is considered a hotspot region for circulation of the virus whereas sporadic cases have been reported from other parts of the country. Our study aims to investigate the genomic diversity of the CCHF virus circulating in Punjab and Khyber Pakhtunkhwa provinces of Pakistan. Between April to September 2022, 46 samples from suspected CCHF patients were tested, with 6 (13%) showing positive RT-PCR results. Among the positive cases, all were male, aged 14-48 years among which 4 were butchers. Three CCHF patients succumbed to the disease. The complete S-M-L-gene fragments of 4 positive samples were sequenced. The S and L segments belonged to the Asia-1 clade and clustered with regional strains from Iran, India, and Afghanistan. One M segment sequence grouped into Africa-2 along with those reported from India during 2016-2019. We report the detection of a reassorted virus (NIH-PAK-CCHF-03|2022) having Asia-1-Africa-2-Asia-1 (S-M-L) segment pattern for the first time from Pakistan. Mutational analysis showed M segments harboring eight mutations (T55A, S80P, T110I, T185A, T189A, A212T, and N239I/T) in the mucin-like domain, five mutations (D250N, T333S, I375V, M401I, A433T), four mutations (N545D, Y657F, K688R, and I824V) in GP38-domain, and three mutations (T1418N, A1431V, and G1449S) in Gc-domain. These findings highlight the significance of whole-genome sequencing of indigenous strains for a better understanding of the CCHFV evolution in Pakistan.