Biology subjects

McMillan, C. L. D.

Publications and source records attributed to McMillan, C. L. D..

4 recordsLinked to original sources

bioRxiv2025

Global transcriptional reprogramming by cytomegalovirus infection suppresses antigen presentation while enhancing migration machinery in murine dendritic cells.

Dendritic cells (DCs) serve dual roles in cytomegalovirus infection: orchestrating antiviral immunity and acting as vehicles for viral dissemination. DC-dependent systemic spread of mouse cytomegalovirus (MCMV) is dependent on expression of a viral G protein-coupled receptor (GPCR) homolog, encoded by M33. We performed global transcriptional profiling of murine DCs infected with either wild-type mouse MCMV or a M33 mutant harbouring a single point mutation (R131Q; denoted M33NQY), which ablates constitutive G protein-dependent signalling. RNA-seq analysis revealed that MCMV induces substantial transcriptional reprogramming, with over 2,400 significantly altered genes affecting key immune and migration pathways. Wild-type MCMV infection resulted in 1,883 upregulated and 658 downregulated genes, while M33NQY infection showed comparable effects with 1,905 upregulated and 668 downregulated genes. Both viruses systematically downregulated the MHC class II antigen presentation machinery, with substantial suppression of H2 molecules, peptide-loading components (H2-DMa/H2-DMb1), and the class II transactivator Ciita (log2FC > -6.4). Pathway analysis revealed coordinated disruption of B cell receptor signalling, leukocyte transendothelial migration, and antigen processing and presentation. A comparison between wild-type and M33NQY-infected DCs demonstrated that while both viruses similarly impair antigen presentation, M33 signalling specifically enhances the expression of genes involved in transendothelial migration, including Spp1 (osteopontin, log2FC = 0.65), cytoskeletal components (Actg1, Actb), adhesion molecules (Icam1), and matrix interaction factors (Tnc, Plau). Network analysis identified critical hub genes, including B2m, Itgb1, Itgam, and Icam1, as key regulatory nodes connecting antigen presentation and migration pathways. This provides molecular evidence for a sophisticated viral strategy that shields MCMV from immune detection while hijacking DC migratory machinery to facilitate dissemination, with M33 serving as a specific enhancer of migration-related pathways. Impact StatementThis study provides the first comprehensive transcriptional profile of mouse cytomegalovirus (MCMV) infection in dendritic cells, revealing a sophisticated viral strategy that simultaneously suppresses antigen presentation while enhancing migration machinery. We identified that MCMV systematically downregulates the entire MHC class II pathway by targeting the master regulator Ciita, while the viral G protein-coupled receptor M33 specifically enhances genes involved in transendothelial migration, including Spp1 (osteopontin). Our network analysis identified critical hub genes connecting immune evasion and migration pathways, providing molecular evidence for how MCMV exploits dendritic cells as vehicles for dissemination while evading immune detection. These findings advance our understanding of betaherpesvirus pathogenesis and highlight potential therapeutic targets to limit viral spread.

microbiology↗

bioRxiv2025

Efficient delivery of mRNA-LNPs in primary and secondary liver cancer

Primary liver cancer is the sixth most prevalent cancer globally and is often diagnosed late, when treatment options are limited. Secondary liver cancer, arising from metastasis of other cancers to the liver, is a common complication of advanced solid cancers and a significant cause of cancer-related morbidity and mortality. Existing treatment options for advanced primary and secondary liver tumours have limited efficacy and new treatment modalities have the potential to improve patient outcomes. mRNA therapeutics are readily delivered to the healthy liver after systemic administration, but their uptake and expression within liver tumours is unclear. Here we show that intravenous delivery of mRNA-LNPs efficiently transfects virtually all hepatocytes in healthy, fibrotic, and cirrhotic liver, and also many cells of spontaneous hepatocellular carcinomas in situ. Delivery of mRNA is also possible to xenograft models of both primary and secondary liver cancer, albeit with attenuated protein expression relative to the normal liver. These findings demonstrate the potential for systemically delivered mRNA-LNP therapies for liver disease and cancer.

molecular biology↗

bioRxiv2024

Vaccine-induced and hybrid immunity against SARS-CoV-2 variants of concern in two cohorts in Queensland, Australia (2021-2022).

The spike glycoprotein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the main target for vaccine development, as antibodies generated against the spike protein are the most immunodominant and neutralizing against the virus. However, variants of concern (VOC), often containing multiple mutations within neutralizing epitopes, confer immune evasion of the response generated by current SARS-CoV-2 vaccines. To assess the immunogenicity and virus-neutralisation ability of antibodies induced by individual or combination of Vaxzevria (AstraZeneca: AZ) and Comirnaty (Pfizer: PZ) vaccines and of a hybrid immunity induced in people who were also infected with SARS-CoV-2, longitudinal sera samples of participants recruited through the David Serisier Research biobank (Mater Research Hospital) or at the University of Queensland were collected. ELISA with a panel of purified Spike proteins from ancestral, alpha, delta and omicron BA.1 and BA.2 VOCs showed significantly (by [~]2 to 6-fold) reduced IgG antibody titres against Spike proteins from Omicron BA.1 and BA.2 compared to ancestral strain regardless of the number of vaccinations or presence of infection. Neutralisation assays showed reduced activity against delta and omicron BA.1, BA.5 and BA.5 VOCs. However, the differences were in general less pronounced than in the ELISA assay and some were not statistically significant, particularly after four (two AZ and two PZ) vaccinations. We also generated by circular polymerase extension reaction an attenuated SARS-CoV-2 strain with deletion of all accessory genes, ORF 3, 6, 7 and 8, based on the ancestral (QLD02) virus backbone (QLD02{Delta}3678) and validated it in virus-neutralization assays with our panel of sera samples. We showed the attenuation of the QLD02{Delta}3678 virus in Vero E6 and human Caco2 cells. We demonstrated that neutralization assays with the wild-type QLD02 virus and QLD02{Delta}3678 virus were concordant, providing a safe platform for neutralisation assays in BSL2/PC2 settings.

microbiology↗

bioRxiv2021

Complete protection by a single dose skin patch delivered SARS-CoV-2 spike vaccine

SARS-CoV-2 has infected over 160 million people and resulted in more than 3.3 million deaths, and we still face many challenges in the rollout of vaccines. Here, we use the high-density microarray patch to deliver a SARS-CoV-2 spike subunit vaccine directly to the skin. We show the vaccine, dry-coated on the patch is thermostable, and delivery of spike via HD-MAP induced greater cellular and antibody immune responses, with serum able to potently neutralize clinically relevant isolates including those from the B.1.1.7 and B.1.351 lineages. Finally, a single dose of HD-MAP-delivered spike provided complete protection from a lethal virus challenge, demonstrating that HD-MAP delivery of a SARS-CoV-2 vaccine is superior to traditional needle-and-syringe vaccination and has the potential to greatly impact the ongoing COVID-19 pandemic.

microbiology↗