Complete genome sequencing of SARS-CoV-2 strains: A pilot survey in Palestine reveals spike mutation H245N.

OBJECTIVES: SARS-CoV-2, severe respiratory syndrome coronavirus-2, is an RNA virus that emerged from China sweeping the globe in the form of a pandemic that became an international public health concern. This pilot study aimed to describe the genetic variation and molecular epidemiology of SARS-CoV-2 in Palestine in fall 2020. RESULTS: To achieve these aims, whole genome sequencing of SARS-CoV-2, phylogenetic analysis, haplotype networking and genetic diversity analysis were performed. These analyses revealed a unique spike mutation H245N that has never been reported before. The phylogenetic analysis depicted that three clusters existed in Palestinian SARS-CoV-2 genome sequences, in which cluster-I comprised the majority of clusters by 90%. Congruently, the haplotype network analysis depicted the same three clusters with a total of 39 haplotypes. The genetic diversity analysis showed that Cluster-I is highly diverse as confirmed by statistically significant mutation rate indices, Tajima's D and Fu-Li's-F tests (- 2.11 and 2.74, respectively), highest number of mutations (Eta = 120), highest number of haplotypes (h = 17), and highest average number of nucleotide differences between any two sequences (S = 118). The study confirmed the high genetic diversity among the Palestinian of SARS-CoV-2 which possessed high number of mutations including one which was reported for the first time.

Tracking of SARS-CoV-2 Alpha variant (B.1.1.7) in Palestine.

As surges of the COVID-19 pandemic continue globally, including in Palestine, several new SARS-CoV-2 variants have been introduced. This expansion has impacted transmission, disease severity, virulence, diagnosis, therapy, and natural and vaccine-induced immunity. Here, 183 whole genome sequences (WGS) were analyzed, of which 129 were from Palestinian cases, 62 of which were collected in 11 Palestinian districts between October 2020 and April 2021 and sequenced completely. A dramatic shift from the wild type to the Alpha variant (B 1.1.7) was observed within a short period of time. Cluster mapping revealed statistically significant clades in two main Palestinian cities, Al-Khalil (Monte Carlo hypothesis test-Poisson model, P = 0.00000000012) and Nablus (Monte Carlo hypothesis test-Poisson model, P = 0.014 and 0.015). The phylogenetic tree showed three main clusters of SARS-CoV-2 with high bootstrap values (>90). However, population genetics analysis showed a genetically homogenous population supported by low Wright's F-statistic values (Fst <0.25), high gene flow (Nm > 3), and statistically insignificant Tajima's D values (Tajima's test, neutrality model prediction, P = 0.02). The Alpha variant, rapidly replaced the wild type, causing a major surge that peaked in April 2021, with an increased COVID-19 mortality rate, especially, in the Al-Khalil and Nablus districts. The source of introduction remains uncertain, despite the minimal genetic variation. The study substantiates the use of WGS for SARS-CoV-2 surveillance as an early warning system to track down new variants requiring effective control.