Evaluation of Approaches to Monitor Staphylococcus aureus Virulence Factor Expression during Human Disease

• Published in: PloS one Vol. 10; no. 2; p. e0116945
• Main Authors: Rozemeijer, Wouter, Fink, Pamela, Rojas, Eduardo, Jones, C. Hal, Pavliakova, Danka, Giardina, Peter, Murphy, Ellen, Liberator, Paul, Jiang, Qin, Girgenti, Douglas, Peters, Remco P. H., Savelkoul, Paul H. M., Jansen, Kathrin U., Anderson, Annaliesa S., Kluytmans, Jan
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.02.2015; Public Library of Science (PLoS)
• Subjects: Adult; Aged; Aged, 80 and over; Analysis; Antigens; Bacterial Capsules - immunology; Capsular polysaccharides; Coagulase - genetics; Coagulase - immunology; Coagulase - metabolism; Drug resistance; Female; Gene expression; Genetic research; Health aspects; Human behavior; Humans; Immune response; Immunoassay; Immunoglobulins; Immunology; Infection; Infections; Male; Manganese; Middle Aged; Nasal Mucosa - microbiology; Pathogens; Patients; Polysaccharides; Proteins; R&D; Research & development; Ribonucleic acid; RNA; Serogroup; Serology; Staphylococcal Infections - microbiology; Staphylococcal Vaccines - immunology; Staphylococcus aureus; Staphylococcus aureus - genetics; Staphylococcus aureus - immunology; Staphylococcus aureus - pathogenicity; Staphylococcus aureus infections; Staphylococcus infections; Transcription; Triose-phosphate isomerase; Vaccines; Virulence; Virulence (Microbiology); Virulence factors; Virulence Factors - genetics; Virulence Factors - immunology; Virulence Factors - metabolism; New York; Netherlands; Pearl River; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0116945

Staphylococcus aureus is a versatile pathogen of medical significance, using multiple virulence factors to cause disease. A prophylactic S. aureus 4-antigen (SA4Ag) vaccine comprising capsular polysaccharide (types 5 and 8) conjugates, clumping factor A (ClfA) and manganese transporter C (MntC) is under development. This study was designed to characterize S. aureus isolates recovered from infected patients and also to investigate approaches for examining expression of S. aureus vaccine candidates and the host response during human infection. Confirmation of antigen expression in different disease states is important to support the inclusion of these antigens in a prophylactic vaccine. Hospitalized patients with diagnosed S. aureus wound (27) or bloodstream (24) infections were enrolled. Invasive and nasal carriage S. aureus isolates were recovered and characterized for genotypic diversity. S. aureus antigen expression was evaluated directly by real-time, quantitative, reverse-transcriptase PCR (qRT-PCR) analysis and indirectly by serology using a competitive Luminex immunoassay. Study isolates were genotypically diverse and all had the genes encoding the antigens present in the SA4Ag vaccine. S. aureus nasal carriage was detected in 55% of patients, and in those subjects 64% of the carriage isolates matched the invasive strain. In swab samples with detectable S. aureus triosephosphate isomerase housekeeping gene expression, RNA transcripts encoding the S. aureus virulence factors ClfA, MntC, and capsule polysaccharide were detected by qRT-PCR. Antigen expression was indirectly confirmed by increases in antibody titer during the course of infection from acute to convalescent phase. Demonstration of bacterial transcript expression together with immunological response to the SA4Ag antigens in a clinically relevant patient population provides support for inclusion of these antigens in a prophylactic vaccine.