Biology subjects

Mulholland, K.

Publications and source records attributed to Mulholland, K..

4 recordsLinked to original sources

bioRxiv2025

Nasopharyngeal colonisation by Streptococcus pneumoniae enhances host anti-viral responses to respiratory virus infection

Viral-bacterial interactions during co-infection are often synergistic and can increase disease severity. However, emerging evidence indicates that some bacteria can antagonise viral infection, although the host responses driving this process remains unclear. Using infant mice co-infected with the nasopharyngeal inhabitant and pathogen Streptococcus pneumoniae and pneumonia virus of mice (PVM) to model antagonistic interactions, we found that prior bacterial colonisation enhances and prolongs anti-viral immune responses during co-infection, compared with viral infection alone. Transcriptomic, immunological, and histological analyses showed that pneumococcal colonisation prior to PVM infection enhanced and prolonged interferon signalling, increased anti-viral cytokine and chemokine protein levels and CD8+ cell responses. Notably, over 50% of differentially expressed host genes during co-infection were not differentially expressed in either infection alone. Our work shows that bacterial colonisation can modulate host immunity, shaping how the immune system responds to incoming viral infections, which has the potential to open novel therapeutic applications. HighlightsO_LIPneumococcal mono-infection in infant mice resulted in a delayed host transcriptomic response that was not detectable until 12 days post-infection. C_LIO_LIHost transcriptomic and immune responses to PVM were minimal except at the peak of viral replication and rapidly returned to baseline levels. C_LIO_LIPrior pneumococcal colonisation enhanced anti-viral immune responses to PVM infection, with more than half of the differentially expressed genes unique to co-infection. C_LIO_LIPneumococcal nasopharyngeal colonisation shapes the immune response, changing how the host responds to incoming viral infections with multiple anti-viral responses that were only transiently activated during PVM mono-infection being active for a longer duration during co-infection C_LI

microbiology↗

bioRxiv2019

PINK1-dependent phosphorylation of Serine111 within the SF3 motif of Rab GTPases impairs effector interactions and LRRK2 mediated phosphorylation at Threonine72

Loss of function mutations in the PINK1 kinase are causal for autosomal recessive Parkinson disease (PD) whilst gain of function mutations in the LRRK2 kinase cause autosomal dominant PD. PINK1 indirectly regulates the phosphorylation of a subset of Rab GTPases at a conserved Serine111 (Ser111) residue within the SF3 motif. Using genetic code expansion technologies we have produced stoichiometric Ser111-phosphorylated Rab8A revealing impaired interactions with its cognate guanine nucleotide exchange factor (GEF) and GTPase activating protein (GAP). In a screen for Rab8A kinases we identify TAK1 and MST3 kinases that can efficiently phosphorylate the Switch II residue Threonine72 (Thr72) in a similar manner as LRRK2. Strikingly we demonstrate that Ser111 phosphorylation negatively regulates the ability of LRRK2 but not MST3 or TAK1 to phosphorylate Thr72 in vitro and demonstrate an interplay of PINK1- and LRRK2-mediated phosphorylation of Rab8A in cells. Finally, we present the crystal structure of Ser111-phosphorylated Rab8A and NMR structure of Ser111-phosphorylated Rab1B that does not demonstrate any major changes suggesting that the phosphorylated SF3 motif may disrupt effector-Switch II interactions. Overall, we demonstrate antagonistic regulation between PINK1-dependent Ser111 phosphorylation and LRRK2-mediated Thr72 phosphorylation of Rab8A suggesting that small molecule activators of PINK1 may have therapeutic potential in patients harbouring LRRK2 mutations.

biochemistry↗

bioRxiv2019

Determining the serotype composition of mixed samples of pneumococcus using whole genome sequencing

Serotyping of Streptococcus pneumoniae is a critical tool in the surveillance of the pathogen and development and evaluation of vaccines. Whole-genome DNA sequencing and analysis is becoming increasingly common and is an effective method for pneumococcal serotype identification of pure isolates. However, because of the complexities of the pneumococcal capsular loci, current analysis software requires samples to be pure (or nearly pure) and only contain a single pneumococcal serotype. We introduce a new software tool called SeroCall, which can identify and quantitate the serotypes present in samples, even when several serotypes are present. The sample preparation, library preparation and sequencing follow standard laboratory protocols. The software runs as fast or faster than existing identification tools on typical computing servers and is freely available under an open source license at https://github.com/knightjimr/serocall. Using samples with known concentrations of different serotypes as well as blinded samples, we were able to accurately quantify the abundance of different serotypes of pneumococcus in mixed cultures, with 100% accuracy for detecting the major serotype and up to 86% accuracy for detecting minor serotypes. We were also able to track changes in serotype frequency over time in an experimental setting. This approach could be applied in both epidemiologic field studies of pneumococcal colonization as well as in experimental lab studies and could provide a cheaper and more efficient method for serotyping than alternative approaches.

bioinformatics↗

bioRxiv2017

Predicting The Impact Of Pneumococcal Conjugate Vaccine Programme Options In Vietnam: A Dynamic Transmission Model

BackgroundCatch-up campaigns (CCs) at the introduction of the pneumococcal conjugate vaccines (PCVs) may accelerate the impact of PCVs. However, limited vaccine supplies may delay vaccine introduction if additional doses are needed for such campaigns. We studied the relative impact of introducing PCV13 with and without catch-up campaign, and the implications of potential introduction delays.\n\nMethodsWe used a dynamic transmission model applied to the population of Nha Trang in Sout central Vietnam. Four strategies were considered: routine vaccination (RV) only, and RV alongside catch-up campaigns among <1y olds (CC1), <2y olds (CC2) and <5y olds (CC5). The model was parameterised with local data on human social contact rates, and was fitted to local carriage data. Post-PCV predictions were based on best estimates of parameters governing post-PCV dynamics, including serotype competition, vaccine efficacy and duration of protection.\n\nResultsOur model predicts elimination of vaccine-type (VT) carriage across all age groups within 10 years of introduction in all scenarios with near-complete replacement by non-VT. Most of the benefit of CCs is predicted to occur within the first 3 years after introduction, with the highest impact in the first year, when IPD incidence is predicted to be 11% (95%CrI 9 - 14%) lower than RV with CC1, 25% (21 - 30 %) lower with CC2 and 38% (32 - 46%) lower with CC5.\n\nHowever, CCs would only prevent more cases of IPD insofar such campaigns do not delay introduction by more than 31 (95%CrI 30 - 32) weeks with CC1, 58 (53 - 63) weeks with CC2 and 89 (78 - 101) weeks for CC5.\n\nConclusionCCs are predicted to offer a substantial additional reduction in pneumococcal disease burden over RV alone, if their implementation does not result in much introduction delay. Those findings are important to help guide vaccine introduction in countries that have not yet introduced PCV, particularly in Asia.

epidemiology↗