Biology subjects

ROY, C. J.

Publications and source records attributed to ROY, C. J..

8 recordsLinked to original sources

bioRxiv2026

Enhanced Antimicrobial Potency and Therapeutic Index of a Defined C12 Quaternary Ammonium Compound

Skin and soft tissue infections (SSTIs) remain a major clinical burden and are complicated by antimicrobial resistance, polymicrobial infections, and biofilm-mediated therapeutic tolerance. Topical antimicrobials can provide localized activity while reducing systemic exposure, but currently available agents are limited by narrow spectra, cytotoxicity, poor antibiofilm activity, and resistance development. We evaluated C12-alkyl(ethylbenzyl)dimethyl ammonium chloride (EQ12), a next-generation quaternary ammonium compound, in vitro as a topical antimicrobial candidate for leading bacterial causes of SSTIs. Broth microdilution assays were used to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Species-selective plating was used to assess bactericidal activity in staphylococcal-P. aeruginosa co-cultures. Crystal violet assays quantified biofilm inhibition against MRSA, P. aeruginosa, and A. baumannii, and serial passage experiments assessed resistance emergence over 14 passages. EQ12 inhibited all species tested, with MICs of 2.3 to 40 micrograms/mL and MBCs of 4.7 to 40 micrograms/mL. EQ12 outperformed benzalkonium chloride and povidone-iodine against Gram-negative isolates and retained bactericidal activity in mixed cultures, although staphylococcal susceptibility decreased in the presence of P. aeruginosa. EQ12 inhibited biofilm formation at sub-MIC to near-MIC concentrations and did not induce resistance in MRSA, P. aeruginosa, or A. baumannii, unlike comparator topical antibiotics. These findings support further development of EQ12 as a topical antimicrobial for SSTI-associated pathogens.

microbiology↗

bioRxiv2026

A Structurally Defined C12-Alkyl Quaternary Ammonium Compound reduces bacterial burden and biofilm in an infected wound model

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) remains a common cause of skin and soft tissue infections, and topical agents that combine antimicrobial activity with wound compatibility are needed. C12-alkyl(ethylbenzyl)dimethyl ammonium chloride is a novel C12 quaternary ammonium molecule (hereafter, EQ12) related to benzalkonium chloride but designed to avoid the compositional heterogeneity and varied potency of conventional C8-C18 benzalkonium mixtures. We evaluated whether topical EQ12 is tolerated in healing wounds and whether it reduces MRSA burden in a splinted murine excisional wound infection model. MethodsFemale CD1 mice underwent 5-mm full-thickness dorsal excisional wounding, silicone splinting, and transparent dressing placement. For tolerability studies, uninfected wounds received EQ12 at 0.1 or 1 mg/mL or phosphate-buffered saline (PBS) and were followed for 14 days. For efficacy studies, wounds were inoculated with 1 x 104 CFU MRSA and treated topically every 8 hours for 3 days beginning 4 hours after infection with EQ12 (1 mg/mL), bacitracin (500 U/mL), or PBS. Wound tissues were harvested on days 2, 4, and 6 for quantitative culture. Dressing-associated biofilm was evaluated by scanning electron microscopy. ResultsEQ12 did not alter body weight, wound inflammation scores, wound area, or percent wound closure compared with PBS in uninfected animals. In infected wounds, day 2 tissue burdens were not significantly different among treatment groups. By day 4, EQ12 significantly reduced MRSA burden compared with PBS, whereas bacitracin did not. By day 6, EQ12-treated animals had significantly lower MRSA burdens than both bacitracin- and PBS-treated controls. Mean tissue burden in the EQ12 group declined from 6.27 log10 CFU/g on day 4 to 5.53 log10 CFU/g on day 6, while bacitracin- and PBS-treated wounds remained persistently colonized. SEM revealed minimal adherent cocci or matrix-like bridging on dressings from EQ12-treated wounds, in contrast to dense microcolonies and biofilm-like structures on bacitracin and PBS dressings. ConclusionsTopical EQ12 was compatible with gross wound healing and reduced MRSA burden in a dressed, splinted murine wound model. These data support continued development of EQ12 as a topical anti-staphylococcal wound-directed antimicrobial.

microbiology↗

bioRxiv2024

Comparative Aerosol Persistence of Hypermucoid Klebsiella pneumoniae

Klebsiella pneumoniae is becoming an increasing cause for concern due to antibiotic resistance and emerging hypervirulent strains. It results in a wide variety of infections, most commonly pneumonia. Immunocompromised individuals and those needing ventilators are among the most at-risk for infection and systemic spread. It is crucial to further understand the behavior of K. pneumoniae to prevent future infections and severe illness. In the past, little research has examined K. pneumoniae in the air to determine whether aerosol transmission is a realistic infection pathway. Therefore, we observed survival of K. pneumoniae suspensions using a 10.7 L custom-built rotating chamber, characterizing laboratory and clinical strains in separate aerosol events. Airborne bacterial suspensions were assessed by culture and quantitative polymerase chain reaction (qPCR). The K2 laboratory strain remained viable until yielding no colony forming units (CFU) at 16 hours. K1 clinical strain did not become unculturable until 32 hours. For each strain, qPCR data showed Ct values slightly increased as time in drum also increased. Our data suggests K. pneumoniae can survive after multiple hours in the air, indicating aerosol transmission of K. pneumoniae is a possible infection pathway.

microbiology↗

bioRxiv2021

Intra-host SARS-CoV-2 evolution in the gut of mucosally-infected Chlorocebus aethiops (African green monkeys)

In recent months, several SARS-CoV-2 variants have emerged that enhance transmissibility and escape host humoral immunity. Hence, the tracking of viral evolutionary trajectories is clearly of great importance. Little is known about SARS-CoV-2 evolution in nonhuman primate models used to test vaccines and therapies and to model human disease. Viral RNA was sequenced from rectal swabs from Chlorocebus aethiops (African green monkeys) after experimental respiratory SARS-CoV-2 infection. Two distinct patterns of viral evolution were identified that were shared between all collected samples. First, mutations in the furin cleavage site that were initially present in the virus as a consequence of VeroE6 cell culture adaptation were subsequently lost in virus recovered in rectal swabs, confirming the necessity of this motif for viral infection in vivo. Three amino acid changes were also identified; ORF 1a S2103F, and spike D215G and H655Y, that were detected in rectal swabs from all sampled animals. These findings are demonstrative of intra-host SARS-CoV-2 evolution unique to this nonhuman primate species and may identify a host-adapted variant of SARS-CoV-2 that would be useful in future development of primate disease models.

microbiology↗

bioRxiv2021

An Orally Available Cathepsin L Inhibitor Protects Lungs Against SARS-CoV-2-Induced Diffuse Alveolar Damage in African Green Monkeys

The COVID-19 pandemic resulted from global infection by the SARS-CoV-2 coronavirus and rapidly emerged as an urgent health issue requiring effective treatments. To initiate infection, the Spike protein of SARS-CoV-2 requires proteolytic processing mediated by host proteases. Among the host proteases proposed to carry out this activation is the cysteine protease cathepsin L. Inhibiting cathepsin L has been proposed as a therapeutic strategy for treating COVID-19. SLV213 (K777) is an orally administered small molecule protease inhibitor that exhibits in vitro activity against a range of viruses, including SARS-CoV-2. To confirm efficacy in vivo, K777 was evaluated in an African green monkey (AGM) model of COVID-19. A pilot experiment was designed to test K777 in a prophylactic setting, animals were pre-treated with 100mg/kg K777 (N=4) or vehicle (N=2) before inoculation with SARS-CoV-2. Initial data demonstrated that K777 treatment reduced pulmonary pathology compared to vehicle-treated animals. A second study was designed to test activity in a therapeutic setting, with K777 treatment (33 mg/kg or 100 mg/kg) initiated 8 hours after exposure to the virus. In both experiments, animals received K777 daily via oral gavage for 7 days. Vehicle-treated animals exhibited higher lung weights, pleuritis, and diffuse alveolar damage. In contrast, lung pathology was reduced in K777-treated monkeys, and histopathological analyses confirmed the lack of diffuse alveolar damage. Antiviral effects were further demonstrated by quantitative reductions in viral load of samples collected from upper and lower airways. These preclinical data support the potential for early SLV213 treatment in COVID-19 patients to prevent severe lung pathology and disease progression.

immunology↗

bioRxiv2021

Effective prophylaxis of COVID-19 in rhesus macaques using a combination of two parentally-administered SARS-CoV-2 neutralizing antibodies

SARS-CoV-2 is a respiratory borne pathogenic beta coronavirus that is the source of a worldwide pandemic and the cause of multiple pathologies in man. The rhesus macaque model of COVID-19 was utilized to test the added benefit of combinatory parenteral administration of two high-affinity anti-SARS-CoV-2 monoclonal antibodies (mAbs; C144-LS and C135-LS) expressly developed to neutralize the virus and modified to extend their pharmacokinetics. After completion of kinetics study of mAbs in the primate, combination treatment was administered prophylactically to mucosal viral challenge. Results showed near complete virus neutralization evidenced by no measurable titer in mucosal tissue swabs, muting of cytokine/chemokine response, and lack of any discernable pathologic sequalae. Blocking infection was a dose-related effect, cohorts receiving lower doses (6, 2 mg/kg) resulted in low grade viral infection in various mucosal sites compared to that of a fully protective dose (20 mg/kg). A subset of animals within this cohort whose infectious challenge was delayed 75 days later after mAb administration were still protected from disease. Results indicate this combination mAb effectively blocks development of COVID-19 in the rhesus disease model and accelerates the prospect of clinical studies with this effective antibody combination.

microbiology↗

bioRxiv2021

Phenotypic and Kinetic Changes of Myeloid Lineage Cells in Innate Response to Chikungunya Infection in Cynomolgus Macaques

Chikungunya is an emerging threat, spreading across multiple continents. The immune response to infection can lead to protection and convalescence, or result in long term sequelae such as arthritis. Early innate immune events during acute infection have been characterized for some cell types, but more must be elucidated with respect to cellular responses of monocytes and other myeloid lineage cells. In addition to their roles in protection and inflammation resolution, monocytes and macrophages are sites for viral replication and reservoirs for the virus. They are also found in joints post-infection, possibly playing a role in long term CHIKV-induced pathology. We examined kinetic and phenotypic changes in myeloid lineage cells, including monocytes, in cynomolgus macaques early after infection with CHIKV. We found increased turnover of monocytes and mDCs early during infection, with an accompanying decreases in both cell types, as well as a simultaneous increase in pDC number. An increase in CD16 and CD14 was seen along with a decrease in monocyte HLA-DR expression within 3 days of infection, potentially indicating monocyte deactivation. A transient decrease in T cells, B cells and NK cells correlates with lymphocytopenia observed during human infections with CHIKV. CD4+ T cell turnover decreased in blood, indicating relocation of cells to effector sites. This data indicates CHIKV influences turnover rates and kinetics of myeloid lineage cells early during infection, and may prove useful in development of therapeutics and evaluation of infection-induced pathogenesis.

immunology↗

bioRxiv2021

Particle Dynamics and Bioaerosol Viability of Aerosolized BCG Vaccine Using Jet and Vibrating Mesh Clinical Nebulizers

BackgroundBacillus Calmette-Guerin (BCG) is a vaccine used to protect against tuberculosis primarily in infants to stop early infection in areas of the world where the disease is endemic. Normally administered as a percutaneous injection, BCG is a live, significantly attenuated bacteria that is now being investigated for its potential within an inhalable vaccine formulation. This work investigates the feasibility and performance of four jet and ultrasonic nebulizers aerosolizing BCG and the resulting particle characteristics and residual viability of the bacteria post-aerosolization. MethodsA jet nebulizer (Collison) outfitted either with a 3- or 6-jet head, was compared to two clinical nebulizers, the vibrating mesh Omron MicroAir and Aerogen Solo devices. Particle characteristics, including aerodynamic particle sizing, was performed on all devices within a common aerosol chamber configuration and comparable BCG innocula concentrations. Integrated aerosol samples were collected for each generator and assayed for bacterial viability using conventional microbiological technique. Results and ConclusionsA batch lot of BCG (Danish) was grown to titer and used in all generator assessments. Aerosol particles within the respirable range were generated from all nebulizers at four different concentrations of BCG. The jet nebulizers produced a uniformly smaller particle size than the ultrasonic devices, although particle concentrations by mass were similar across all devices tested with the exception of the Aerogen Solo, which resulted in a very low concentration of BCG aerosols. The resulting measured viable BCG aerosol concentration fraction produced by each device approximated one another; however, a measurable decrease of efficiency and overall viability reduction in the jet nebulizer was observed in higher BCG inoculum starting concentrations, whereas the vibrating mesh nebulizer returned a remarkably stable viable aerosol fraction irrespective of inoculum concentration.

biophysics↗