Oral Presentation 21st Lancefield International Symposium for Streptococci and Streptococcal Diseases 2022

Antimicrobial efficiency of antisense peptide nucleic acids (PNAs) in Streptococcus pneumoniae (#58)

Corina Abt 1 , Gina Barkowsky 1 , Irina Poehner 1 , Adam Bieda 1 , Sven Hammerschmidt 2 , Anette Jacob 3 4 , Bernd Kreikemeyer 1 , Nadja Patenge 1
  1. Institute for Medical Microbiology, Virology and Hygiene, Rostock University Medical Center, Rostock, Germany
  2. Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
  3. Peps4LS GmbH, INF 583, Heidelberg, Germany
  4. Functional Genome Analysis, Deutsches Krebsforschungszentrum, Heidelberg, Germany

Background

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia and responsible for multiple other infectious syndromes. Since resistance to antibiotics and emergence of non-vaccine serotypes increase, novel therapeutic options are urgently needed. Antisense peptide nucleic acids (PNAs) were shown to reduce growth of several pathogenic bacteria in various infection models. In this work, antimicrobial activity of several cell-penetrating peptide (CPP)-conjugated PNA constructs was investigated in S. pneumoniae. 

 

Methods

Antimicrobial activity of CPP-antisense PNAs targeting the transcript of gyrA (encoding the DNA gyrase subunit A) was studied in vitro by killing assays and MIC determination. Relative abundance of target gene transcripts following CPP-PNA treatment, was measured employing reverse transcription followed by qPCR. Efficiency of the CPP-PNA conjugates was verified in vivo using a Galleria mellonella infection model.

 

Results

(RXR)4XB and TAT-HIV -coupled antisense PNAs showed antimicrobial activity in pneumococci. Treatment with (RXR)4XB-anti gyrA PNAs resulted in complete eradication of S. pneumoniae TIGR4 within 12 h. The relative transcript abundance of gyrA was reduced following treatment to 50 % compared to untreated pneumococci, indicating a specific antisense effect. Treatment with (RXR)4XB-anti gyrA PNAs increased survival of Galleria mellonella larvae infected with S. pneumoniae TIGR4.

 

Conclusions

CPP-coupled antisense PNAs exhibit target gene specific antimicrobial activity in S. pneumoniae.   In future studies, more effective carrier molecules will be identified to improve the efficiency of antisense PNA constructs. Furthermore, off-target effects will be analyzed using RNAseq technology.