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Genomic analysis unveils the role of genome degradation events and gene flux in the emergence and persistence of S . Paratyphi A lineages

Article scientifique 2022 Anglais

Résumé

Abstract Paratyphoid fever caused by S . Paratyphi A is endemic in parts of Asia and Sub-Saharan Africa. The proportion of enteric fever cases caused by S . Paratyphi A has substantially increased, yet only limited data is available on the population structure and genetic diversity of this serovar. We examined the phylogenetic distribution and evolutionary trajectory of S . Paratyphi A isolates collected as part of the Indian enteric fever surveillance study “Surveillance of Enteric Fever in India (SEFI).” In the study period (2017-2020), S . Paratyphi A comprised 17.6% (441/2503) of total enteric fever cases in India, with the isolates highly susceptible to all the major antibiotics used for treatment except fluoroquinolones. Phylogenetic analysis clustered the global S . Paratyphi A collection into seven lineages (A-G), and the present study isolates were distributed in lineages A, C and F. Our analysis documented that the genome degradation events and gene acquisitions or losses play a major role in the evolution of new S . Paratyphi A lineages/sub-lineages. A total of 10 pseudogene-forming mutations possibly associated with the emergence of lineages were identified. Pan-genome analysis identified the insertion of P2/PSP3 phage and acquisition of IncX1 plasmid during the selection in 2.3.2/2.3.3 and 1.2.2 genotypes, respectively. We also identified that the six characteristic missense mutations associated with the lipopolysaccharide (LPS) biosynthesis genes of S . Paratyphi A confer only a low structural impact and would therefore have minimal impact on vaccine effectiveness. Since S . Paratyphi A is human restricted, high levels of genetic drift are not expected unless these bacteria transmit to naive hosts. However, public-health investigation and intervention by means of genomic surveillance would be continually needed to avoid S . Paratyphi A serovar becoming a public health threat similar to the S . Typhi of today.

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Jacob, J., Pragasam, A., Vasudevan, K., Velmurugan, A., T, M., Thirumoorthy, T., Ray, P., Gupta, M., Kapil, A., Bai, S., Nagaraj, S., Saigal, K., Chandola, T., Thomas, M., Bavdekar, A., Ebenezer, S., Shastri, J., De, A., Dutta, S., Alexander, A., Koshy, R., Jinka, D., Singh, A., Srivastava, S., Anandan, S., Dougan, G., John, J., Kang, G., Veeraraghavan, B., Mutreja, A. (2022). Genomic analysis unveils the role of genome degradation events and gene flux in the emergence and persistence of S . Paratyphi A lineages. https://doi.org/10.1101/2022.06.09.495420

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