Ayleen Parra Calisto

Ms. Ayleen Parra Calisto


Research Focus & Metrics

Academic Career Length

1Year (2026-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 May 2026 in Microorganisms
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Journal Article
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ACAyleen Parra Calisto
Ayleen Parra Calisto
CSCarlos Santiviago
Carlos Santiviago
CBCarlos J Blondel
Carlos J Blondel
CRCarla Vargas Del Río
Carla Vargas Del Río
VBValentina Briceño
Valentina Briceño
DPDavid Pezoa
David Pezoa
The type VI secretion system (T6SS) is a contact-dependent, contractile multiprotein complex widely distributed among Gram-negative bacteria. It mediates the translocation of effector proteins into bacterial competitors and eukaryotic host cells, promoting environmental fitness and contributing to virulence. In Salmonella, five pathogenicity islands encoding T6SSs (SPI-6, SPI-19, SPI-20, SPI-21, and SPI-22) have been described, along with an expanding repertoire of associated effector proteins. However, their global diversity and distribution remain incompletely resolved due to limited genomic sampling. To address this, we analyzed a curated dataset of 490 Salmonella genomes representing 45 serotypes. T6SS regions were identified using SecreT6, revealing that SPI-6 is widely distributed, whereas SPI-19, SPI-20, and SPI-21 are restricted to a subset of serotypes. SPI-20 and SPI-21 were exclusively found in S. enterica subsp. arizonae and diarizonae, while SPI-22 was absent from all analyzed genomes. All open reading frames within T6SS clusters were then analyzed for effector prediction and functional annotation. This approach recovered 32 out of 45 previously described T6SS effectors and identified several novel candidates. These included a cytidine deaminase with predicted DNase activity in SPI-6: two candidate nuclease effectors in SPI-19 with DNase and RNase activities, and four putative effectors in SPI-21, including enzymes with predicted peptidoglycan hydrolase activity, a potential inhibitor of eukaryotic ATPases, and a membrane pore-forming toxin. Additionally, a putative phospholipase effector was identified within a VgrG-associated genomic island in a subset of S. enterica subsp. diarizonae isolates. Collectively, these findings expand the known repertoire of Salmonella T6SS effector proteins and highlight their functional diversity.