Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Phagosomal Escape, Intracellular Survival and Induction of Small Colony Variants of Staphylococcus aureus USA300 in RAW 264.7 Murine Macrophages

Dalida Angela Bivona
,
Carmelo Bonomo
ORCID logo ,
Paolo Giuseppe Bonacci
,
Alessia Mirabile
,
Grete Francesca Privitera
ORCID logo ,
Giuseppe Caruso
,
Filippo Caraci
,
Nicolò Musso
ORCID logo ,
Dafne Bongiorno
* ,
Stefania Stefani
Version 1 : Received: 23 March 2023 / Approved: 27 March 2023 / Online: 27 March 2023 (12:16:26 CEST)

How to cite: Bivona, D.A.; Bonomo, C.; Bonacci, P.G.; Mirabile, A.; Privitera, G.F.; Caruso, G.; Caraci, F.; Musso, N.; Bongiorno, D.; Stefani, S. Phagosomal Escape, Intracellular Survival and Induction of Small Colony Variants of Staphylococcus aureus USA300 in RAW 264.7 Murine Macrophages. Preprints 2023, 2023030461. https://doi.org/10.20944/preprints202303.0461.v1 Bivona, D.A.; Bonomo, C.; Bonacci, P.G.; Mirabile, A.; Privitera, G.F.; Caruso, G.; Caraci, F.; Musso, N.; Bongiorno, D.; Stefani, S. Phagosomal Escape, Intracellular Survival and Induction of Small Colony Variants of Staphylococcus aureus USA300 in RAW 264.7 Murine Macrophages. Preprints 2023, 2023030461. https://doi.org/10.20944/preprints202303.0461.v1

Abstract

Phagosomal escape and intracellular survival, often accompanied by Small Colony Variants (SCVs) formation, are typical features of infections caused by S. aureus. The survival in macro-phages favours S. aureus dissemination and complicates treatment. RAW 264.7 murine macro-phages infected with S. aureus USA300 and treated with erythromycin and 20mM carnosine, alone and in combination, were used as experimental model. SCVs were isolated from all treat-ment conditions, but only those undergoing the pressure of combined erythromycin and carnosine for 48 hours were stable for at least six passages on blood agar. Nucleic acid extraction was car-ried out for S. aureus USA300 wild-type and stable SCVs. Whole Genome Sequencing (WGS) was performed using Illumina DNA Prep and Illumina MiSeq, and quantitative reverse transcription PCR was performed. WGS analysis did not yield mutations pointing to differences between S. au-reus USA300 and stable SCVs, therefore the focus was shifted to evaluating gene expression vari-ations. Genes such as zur, mntR, uhpt, fur, sdrE were shown to be significantly up-regulated in SCVs compared to S. aureus USA300 wild-type, suggesting a global change that allows adapta-tion to intracellular persistence, including protection from inflammatory response and evasion of the immune system.

Keywords

Staphylococcus aureus; Small Colony Variants; Carnosine; RAW 264.7 murine macrophages; Host-Pathogen Interaction

Subject

Biology and Life Sciences, Virology

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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