Biology subjects

Killeen, S. Z.

Publications and source records attributed to Killeen, S. Z..

3 recordsLinked to original sources

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

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↗