The first mutations of the Covid-19 similar to the now defined delta variant were found in water samples as far back as February this year, a team of researchers have said as they called for looking into option of wastewater-based genomic surveillance instead of just relying on conventional genomic surveillance based on clinical samples being done presently.
The researchers from the Gujarat Biotechnology Research Centre and Indian Institute of Technology in Gandhinagar (IIT-Gn), in their study which was uploaded as a pre-print on July 8, said, the wastewater-based genomic surveillance can identify all the variants shed by the infected individuals in the population, as it does also include RNA fragmented shredded by clinically escaped asymptomatic patients.
They reached to this conclusion after analysing four samples to detect key mutations in the SARS-CoV-2 genome as they tracked circulating variants in Ahmedabad during the first wave (September/ November 2020) and before the second wave (in February 2021) of Covid-19 in India, said the study which is yet to be peer reviewed.
The analysis showed a total of 35 mutations in the spike protein across four samples categorized into 23 types.
“We noticed the presence of spike protein mutations linked to the VOC-21APR-02; B.1.617.2 lineage (Delta variant) with 57 per cent frequency in wastewater samples of February 2021.
“The key spike protein mutations were T19R, L452R, T478K, D614G, & P681R and deletions at 22029 (6 bp), 28248 (6 bp), & 28271 (1 bp). Interestingly, these mutations were not observed in the samples of September and November last year but appeared before the devastating second wave of Covid-19, which started in early April 2021 in India, that caused rapid transmission and deaths all over India,” they said.
The researchers found the genetic traces of the B.1.617.2 in samples of early February 2021 i.e., more than a month before the first clinically confirmed case of the same variant in March 2021 in Ahmedabad, Gujarat, said the study authored by seven researchers from the two institute, with Madhvi Joshi of GBRC as the lead author.