Biology subjects

Briggs, K.

Publications and source records attributed to Briggs, K..

4 recordsLinked to original sources

bioRxiv2024

Morphologic characterization and cytokine response of chicken bone-marrow derived dendritic cells to infection with high and low pathogenic avian influenza virus

Dendritic cells (DCs) are professional antigen-presenting cells, which are key components of the immune system and involved in the early immune response. DCs are specialized in capturing, processing, and presenting antigens to facilitate immune interactions. Chickens infected with avian influenza virus (AIV) demonstrate a wide range of clinical symptoms, based on pathogenicity of the virus. Low pathogenic avian influenza (LPAI) viruses typically induce mild clinical signs, whereas high pathogenic avian influenza (HPAI) induce more severe disease, which can lead to death within days. For this study, chicken bone marrow-derived DC (ckBM-DC)s were produced and infected with high and low pathogenic avian influenza viruses of H5N2 or H7N3 subtypes to characterize innate immune responses, study effect on cell morphology, and evaluate virus replication. A strong proinflammatory response, including chicken interleukin-1{beta}, and stimulation of the interferon response pathway were observed at 8 hours post infection. Microscopically, the DCs underwent morphological changes from classic elongated dendrites to a more general rounded shape that eventually lead to cell death with the presence of scattered cellular debris. Differences in onset of morphologic changes were observed between H5 and H7 subtypes. Increases in viral titers demonstrated that both HPAI and LPAI are capable of infecting and replicating in DCs. The elevated expression of infected DCs may be indicative with a dysregulation of the immune response typically seen with HPAI infections.

immunology↗

bioRxiv2024

Modeling reveals the strength of weak interactions in stacked ring assembly

Cells employ many large macromolecular machines for the execution and regulation of processes that are vital for cell and organismal viability. Interestingly, cells cannot synthesize these machines as functioning units. Instead, cells synthesize the molecular parts that must then assemble into the functional complex. Many important machines, including chaperones like GroEL and proteases like the proteasome, are comprised protein rings that are stacked on top of one another. While there is some experimental data regarding how stacked-ring complexes like the proteasome self-assemble, a comprehensive understanding of the dynamics of stacked ring assembly is currently lacking. Here, we developed a mathematical model of stacked trimer assembly, and performed an analysis of the assembly of the stacked homomeric trimer, which is the simplest stacked ring architecture. We found that stacked rings are particularly susceptible to a form of kinetic trapping that we term "deadlock," in which the system gets stuck in a state where there are many large intermediates that are not the fully-assembled structure, but that cannot productively react. When interaction affinities are uniformly strong, deadlock severely limits assembly yield. We thus predicted that stacked rings would avoid situations where all interfaces in the structure have high affinity. Analysis of available crystal structures indicated that indeed the majority - if not all - of stacked trimers do not contain uniformly strong interactions. Finally, to better understand the origins of deadlock, we developed a formal pathway analysis and showed that, when all the binding affinities are strong, many of the possible pathways are utilized. In contrast, optimal assembly strategies utilize only a small number of patwhays. Our work suggests that deadlock is a critical factor influencing the evolution of macromolecular machines, and provides general principles for not only understanding existing machines but also for the design of novel structures that can self-assemble efficiently. Statement of SignificanceUnderstanding the assembly macromolecular machines is important for understanding a wide range of cellular processes. Here, we use mathematical models to study the assembly of stacked rings, which are a common motif in these machines. Our models revealed that these complexes can readily get "stuck" during assembly when the binding affinity between subunits is too strong. This suggests an evolutionary pressure to favor weaker interactions, and our analysis of solved structures confirmed this prediction. Our findings not only contribute to the fundamental understanding of assembly but also offer insights into the evolutionary pressures shaping the architecture of stacked rings, and have implications for both cell and synthetic biology.

biophysics↗

bioRxiv2023

SARS-CoV-2 utilization of ACE2 from different bat species allows for virus entry and replication in vitro

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) is believed to have a zoonotic origin. Bats are a suspected natural host of SARS-CoV-2 because of sequence homology with other bat coronaviruses. Understanding the origin of the virus and determining species susceptibility is essential for managing the transmission potential during a pandemic. In a previous study, we established an in vitro animal model of SARS-CoV-2 susceptibility and replication in a non-permissive avian fibroblast cell line (DF1) based on expression of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) from different animal species. In this work, we express the ACE2 of seven bat species in DF1 cells and determine their ability to support attachment and replication of the original SARS-CoV-2 Wuhan lineage virus, as well as two variants, Delta and Lambda. We demonstrate that the ACE2 receptor of all seven species: little brown bat (Myotis lucifugus), great roundleaf bat (Hipposideros armiger), Pearsons horseshoe bat (Rhinolophus pearsonii), greater horseshoe bat (Rhinolophus ferrumequinum), Brazilian free-tailed bat (Tadarida brasiliensis), Egyptian rousette (Rousettus aegyptiacus), and Chinese rufous horseshoe bat (Rhinolophus sinicus), made the DF1 cells permissible to the three isolates of SARS-CoV-2. However, the level of virus replication differed between bat species and variant tested. In addition, the Wuhan lineage SARS-CoV-2 virus replicated to higher titers (104.5-105.5 TCID50) than either variant virus (103.5-104.5 TCID50) on pass 1. Interestingly, all viruses tested grew to higher titers (approximately 106 TCID50) when cells expressed the human ACE2 gene compared to bat ACE2. This study provides a practical in vitro method for further testing of animal species for potential susceptibility to current and emerging SARS-CoV-2 viruses.

molecular biology↗

bioRxiv2022

Efficacy of Parainfluenza Virus 5 (PIV5)-vectored Intranasal COVID-19 Vaccine as a Single Dose Vaccine and as a Booster against SARS-CoV-2 Variants

Immunization with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines has greatly reduced coronavirus disease 2019 (COVID-19)-related deaths and hospitalizations, but waning immunity and the emergence of variants capable of immune escape indicate the need for novel SARS-CoV-2 vaccines. An intranasal parainfluenza virus 5 (PIV5)-vectored COVID-19 vaccine CVXGA1 has been proven efficacious in animal models and blocks contact transmission of SARS-CoV-2 in ferrets. CVXGA1 vaccine is currently in human clinical trials in the United States. This work investigates the immunogenicity and efficacy of CVXGA1 and other PIV5-vectored vaccines expressing additional antigen SARS-CoV-2 nucleoprotein (N) or SARS-CoV-2 variant spike (S) proteins of beta, delta, gamma, and omicron variants against homologous and heterologous challenges in hamsters. A single intranasal dose of CVXGA1 induces neutralizing antibodies against SARS-CoV-2 WA1 (ancestral), delta variant, and omicron variant and protects against both homologous and heterologous virus challenges. Compared to mRNA COVID-19 vaccine, neutralizing antibody titers induced by CVXGA1 were well-maintained over time. When administered as a boost following two doses of a mRNA COVID-19 vaccine, PIV5-vectored vaccines expressing the S protein from WA1 (CVXGA1), delta, or omicron variants generate higher levels of cross-reactive neutralizing antibodies compared to three doses of a mRNA vaccine. In addition to the S protein, the N protein provides added protection as assessed by the highest body weight gain post-challenge infection. Our data indicates that PIV5-vectored COVID-19 vaccines, such as CVXGA1, can serve as booster vaccines against emerging variants. ImportanceWith emerging new variants of concern (VOC), SARS-CoV 2 continues to be a major threat to human health. Approved COVID-19 vaccines have been less effective against these emerging VOCs. This work demonstrates the protective efficacy, and strong boosting effect, of a new intranasal viral-vectored vaccine against SARS-CoV-2 variants in hamsters.

microbiology↗