RESUMEN
We report a novel piece-wise isothermal nucleic acid test (PINAT) for diagnosing pathogen-associated RNA that embeds an exclusive DNA-mediated specific probing reaction with the backbone of an isothermal reverse-transcription cum amplification protocol as a unified single-step procedure. This single step sample-to-result test method has been seamlessly integrated in an inexpensive, scalable, pre-programmable and portable instrument, resulting in a generic platform technology for detecting nucleic acid from a wide variety of pathogens. The test exhibited high sensitivity and specificity of detection when assessed using 200 double-blind patient samples for detecting SARS-CoV-2 infection conducted by the Indian Council of Medical Research (ICMR), reporting a positive and negative percent agreement of 94.6% and 98% respectively. We also established its efficacy in detecting influenza-A infection, performing the diagnosis at the point of collection with uncompromised detection rigor. The envisaged trade-off between advanced laboratory-based procedures with the elegance of common rapid tests renders the innovation to be ideal for deployment in resource-limited settings towards catering the needs of the underserved.
RESUMEN
Accumulation of mutations within the genome is the primary driving force for viral evolution within an endemic setting. This inherent feature often leads to altered virulence, infectivity and transmissibility as well as antigenic shift to escape host immunity, which might compromise the efficacy of vaccines and antiviral drugs. Therefore, we aimed at genome-wide analyses of circulating SARS-CoV-2 viruses for the emergence of novel co-existing mutations and trace their spatial distribution within India. Comprehensive analysis of whole genome sequences of 441 Indian SARS-CoV-2 strains revealed the occurrence of 33 different mutations, 21 being distinctive to India. Emergence of novel mutations were observed in S glycoprotein (7/33), NSP3 (6/33), RdRp/NSP12 (4/33), NSP2 (2/33) and N (2/33). Non-synonymous mutations were found to be 3.4 times more prevalent than synonymous mutations. We classified the Indian isolates into 22 groups based on the co-existing mutations. Phylogenetic analyses revealed that representative strain of each group divided themselves into various sub-clades within their respective clades, based on the presence of unique co-existing mutations. India was dominated by A2a clade (55.60%) followed by A3 (37.38%) and B (7%), but exhibited heterogeneous distribution among various geographical regions. The A2a clade mostly predominated in East India, Western India and Central India, whereas A3 clade prevailed in South and North India. In conclusion, this study highlights the divergent evolution of SARS-CoV-2 strains and co-circulation of multiple clades in India. Monitoring of the emerging mutations would pave ways for vaccine formulation and designing of antiviral drugs.
RESUMEN
BackgroundThis is a comprehensive analysis of 46 Indian SARS-CoV-2 genome sequences available from the NCBI and GISAID repository during early 2020. Evolutionary dynamics, gene-specific phylogeny and emergence of the novel co-evolving mutations in nine structural and non-structural genes among circulating SARS-CoV-2 strains in ten states of India have been assessed. Materials and methods46 SARS-CoV-2 nucleotide sequences submitted from India were downloaded from the GISAID (39/46) or from NCBI (7/46) database. Phylogenetic study and analyses of mutation were based on the nine structural and non-structural genes of SARS-CoV-2 strains. Secondary structure of RdRP/NSP12 protein was predicted with respect to the novel A97V mutation. ResultsPhylogenetic analyses revealed the evolution of "genome-type clusters" and adaptive selection of "L" type SARS-CoV-2 strains with genetic closeness to the bat SARS-like coronaviruses than pangolin or MERS-CoVs. With regards to the novel co-evolving mutations, 2 groups are seen to circulate in India at present: the "major group" (52.2%) and the "minor group" (30.4%), harboring four and five co-existing mutations, respectively. The "major group" mutations fall in the A2a clade. All the minor group mutations, except 11083G>T (L37F, NSP6) were unique to the Indian isolates. ConclusionThe study highlights rapidly evolving SARS-CoV-2 virus and co-circulation of multiple clades and sub-clades, driving this pandemic worldwide. This comprehensive study is a potential resource for monitoring the novel mutations in the viral genome, changes in viral pathogenesis, for designing vaccines and other therapeutics.
