Biology subjects

Matthews, A. J.

Publications and source records attributed to Matthews, A. J..

3 recordsLinked to original sources

bioRxiv2021

A genetic interaction screen in Streptococcus pneumoniae identifies functionally redundant vaccine candidate proteins CbpC and CbpJ

Streptococcus pneumoniae is a Gram-positive bacterium that asymptomatically colonizes the nasopharynx and can disseminate to sterile sites resulting in pneumococcal diseases such as pneumonia, otitis media, bacteremia, and meningitis. Due to increased incidence of invasive disease caused by serotypes that are not included in available polysaccharide vaccines, there is a need for a broadly protective protein vaccine to complement the polysaccharide based vaccines. To limit immune escape such a vaccine would ideally target proteins that are essential for virulence. However, the genetic robustness of S. pneumoniae results in few surface exposed proteins being essential for virulence. Here we carried out a genetic interaction screen to identify functionally redundant surface protein pairs that could be used as bivalent protein vaccines, based on the observation that together, these protein pairs are essential for virulence. We identified four pairs of functionally redundant surface proteins that displayed a significant competitive disadvantage during murine pneumococcal pneumonia. Immunization with the most attenuated pair, CbpC and CbpJ, resulted in production of high titers of specific antibodies and a modest increased median survival times of mice challenged with pneumococcal pneumonia. This study demonstrates a method to identify essential pairs of surface-associated virulence proteins that could be widely applied to many bacterial pathogens. IMPORTANCEInfection by Streptococcus pneumoniae can result in life-threatening illness. Current licensed polysaccharide vaccines only protect against serotypes that are present in the vaccine - at most 23 serotypes of the total 100 identified, circulating serotypes. There remains a need for a widely protective protein vaccine that is effective against most circulating strains of S. pneumoniae. The significance of our research is in developing a method to identify functionally redundant protein pairs as potential vaccine candidates, which could inform the development of effective bivalent protein vaccines for many bacterial pathogens.

microbiology↗

bioRxiv2020

A Tn-seq screen of Streptococcus pneumoniae uncovers DNA repair as the major pathway for desiccation tolerance and transmission

Streptococcus pneumoniae is an opportunistic pathogen that is a common cause of serious invasive diseases such as pneumonia, bacteremia, meningitis, and otitis media. Transmission of this bacterium has classically been thought to occur through inhalation of respiratory droplets and direct contact with nasal secretions. However, the demonstration that S. pneumoniae is desiccation tolerant, and therefore environmentally stable for extended periods of time, opens up the possibility that this pathogen is also transmitted via contaminated surfaces (fomites). To better understand the molecular mechanisms that enable S. pneumoniae to survive periods of desiccation, we performed a high throughput transposon sequencing (Tn-seq) screen in search of genetic determinants of desiccation tolerance. We identified 42 genes whose disruption reduced desiccation tolerance, and 45 genes that enhanced desiccation tolerance. The nucleotide excision repair pathway was the most enriched category in our Tn-seq results, and we found that additional DNA repair pathways are required for desiccation tolerance, demonstrating the importance of maintaining genome integrity after desiccation. Deletion of the nucleotide excision repair gene uvrA resulted in decreased transmission efficiency between infant mice, indicating a correlation between desiccation tolerance and pneumococcal transmission. Understanding the molecular mechanisms that enable pneumococcal persistence in the environment may enable targeting of these pathways to prevent fomite transmission, thereby preventing the establishment of new colonization and any resulting invasive disease.

microbiology↗

bioRxiv2020

KIAA1841, a novel SANT and BTB domain-containing protein, inhibits class switch recombination

Class switch recombination (CSR) enables B cells to produce different immunoglobulin isotypes and mount an effective immune response against pathogens. Timely resolution of CSR prevents damage due to an uncontrolled and prolonged immune response. While many positive regulators of CSR have been described, negative regulators of CSR are relatively unknown. Using a shRNA library screen in a mouse B cell line, we have identified the novel protein KIAA1841 (NM_027860) as a negative regulator of CSR. KIAA1841 is an uncharacterized protein of 82kD containing SANT and BTB domains. The BTB domain of KIAA1841 exhibited characteristic properties such as self-dimerization and interaction with co-repressor proteins. Overexpression of KIAA1841 inhibited CSR in primary mouse splenic B cells, and inhibition of CSR is dependent on the BTB domain while the SANT domain is largely dispensable. Thus, we have identified a new member of the BTB family that serves as a negative regulator of CSR.

molecular biology↗