Biology subjects

Weilhammer, D.

Publications and source records attributed to Weilhammer, D..

5 recordsLinked to original sources

bioRxiv2026

A Selenium-Deficient Mouse Model of Mouse-Adapted SARS-CoV-2 Demonstrates Variant Emergence Observed in SARS-CoV-2 Pandemic Variants

Host selenium deficiency has been shown to generate novel genetic variants in RNA viruses. With the predicted rise of selenium deficiency globally, we sought to determine if host selenium deficiency can be a predictive factor for RNA virus variant emergence. We utilized a selenium-deficient BALB/c mouse model to investigate how host selenium status influences the emergence of viral variants in mouse-adapted SARS-CoV-2. Mice were maintained on control or selenium-deficient diets and subjected to sequential rounds of diet-matched viral passage to generate diet-specific virus populations. Deep sequencing of passaged viral populations revealed that selenium-deficient passage drove a marked increase in inter-host genomic heterogeneity and produced a distinct mutational profile relative to control passage. Eighteen mutations were identified as unique to selenium-deficient passage, including variants previously observed during natural human SARS-CoV-2 evolution. These mutations were largely maintained at sub-consensus frequencies, indicating that selenium deficiency can expand the viral quasispecies landscape that enrichs reservoirs of adaptive potential. To determine how this altered mutant spectrum affected pathogenesis, we challenged normal diet-fed adult and aged BALB/c mice with control- or selenium-deficient-passaged virus. Although overt differences in weight loss, survival, and viral burden were generally modest, selenium-deficient-passaged virus induced pronounced increases in antiviral cytokine expression. Together, these findings identify host selenium deficiency as a driver of RNA virus population diversification and show that nutritionally stressed animal models can reproducibly generate mutations observed in nature.

microbiology↗

bioRxiv2024

Early immune response to Coccidioides is characterized by robust neutrophil and fibrotic macrophage recruitment and differentiation

Coccidioidomycosis, or Valley fever, is an emerging respiratory disease caused by soil dwelling fungi of the Coccidioides genus that is expected to spread from the southwest into the central U.S. by 2050. While 60% of infections are asymptomatic, the other 40% of patients experience a range of symptoms, from self-limiting pneumonia to life-threatening disseminated disease. The immunological events that underlie the progression to severe disease remain under defined. Here, we probed the early immune response to Coccidioides using a high dose of an attenuated strain of C. posadasii in a mouse model of infection coupled with single-cell RNA sequencing. At 24 hours post-infection, robust immune infiltration is detected in the lung, marked by high levels of inflammatory PD-L1+ neutrophils and fungal-contact dependent pro-fibrotic Spp1+ macrophages. These findings elucidate the early dynamics of the host response to Coccidioides and provide a deeper understanding of host-pathogen interactions in the lung. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/609001v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@198a77forg.highwire.dtl.DTLVardef@11c9207org.highwire.dtl.DTLVardef@b71257org.highwire.dtl.DTLVardef@115447d_HPS_FORMAT_FIGEXP M_FIG C_FIG ImportanceBy examining early immune dynamics in the lungs, we uncover critical insights into how myeloid cells, particularly neutrophils and macrophages, are recruited and differentiated during Coccidioides infection. The discovery of specific immune cell subsets, such as PD-L1+ neutrophils and Spp1+ macrophages, which are associated with inflammation and fibrosis, highlights potential targets for therapeutic intervention. These findings provide a deeper understanding of the host-pathogen interactions that occur during Coccidioides infection, offering valuable directions for developing more effective treatments and preventive strategies against this increasingly prevalent disease.

immunology↗

bioRxiv2024

Spatiotemporal Analysis of Lung Immune Dynamics in Lethal Coccidioides posadasii Infection

Coccidioidomycosis, or Valley Fever, is a lung disease caused by inhalation of Coccidioides fungi, prevalent in the Southwestern U.S., Mexico, and parts of Central and South America. 350,000 cases are reported annually in the U.S., although that number is expected to increase as climate change expands fungal geographic range. While 60% of infections are asymptomatic, the symptomatic 40% are often misdiagnosed due to similarities with bronchitis or pneumonia. A small subset of infection progress to severe illness, necessitating a better understanding of immune responses during lethal infection. Using single-cell RNA sequencing and spatial transcriptomics, we characterized lung responses during Coccidioides infection. We identified monocyte-derived Spp1-expressing macrophages as potential mediators of tissue remodeling and fibrosis, marked by high expression of profibrotic and proinflammatory transcripts. These macrophages showed elevated TGF-{beta} and IL-6 signaling, pathways involved in fibrosis pathogenesis. Additionally, we observed significant neutrophil infiltration and defective lymphocyte responses, indicating severe adaptive immunity dysregulation in lethal, acute infection. These findings enhance our understanding of Coccidioides infection and suggest new therapeutic targets. ImportanceCoccidioidomycosis, commonly known as Valley Fever, is a lung disease caused by the inhalation of Coccidioides fungi, which is prevalent in the Southwestern U.S., Mexico, and parts of Central and South America. With climate change potentially expanding the geographic range of this fungus, understanding the immune responses during severe infections is crucial. Our study used advanced techniques to analyze lung responses during Coccidioides infection, identifying specific immune cells that may contribute to tissue damage and fibrosis. These findings provide new insights into the disease mechanisms and suggest potential targets for therapeutic intervention, which could improve outcomes for patients suffering from severe Valley Fever.

immunology↗

bioRxiv2023

Host tracheal and intestinal microbiomes inhibit Coccidioides growth in vitro

Coccidioidomycosis, also known as Valley fever, is a disease caused by the fungal pathogen Coccidioides. Unfortunately, patients are often misdiagnosed with bacterial pneumonia leading to inappropriate antibiotic treatment. Soil bacteria B. subtilis-like species exhibits antagonistic properties against Coccidioides in vitro; however, the antagonistic capabilities of host microbiota against Coccidioides are unexplored. We sought to examine the potential of the tracheal and intestinal microbiomes to inhibit the growth of Coccidioides in vitro. We hypothesized that an uninterrupted lawn of microbiota obtained from antibiotic-free mice would inhibit the growth of Coccidioides while partial in vitro depletion through antibiotic disk diffusion assays would allow a niche for fungal growth. We observed that the microbiota grown on 2xGYE (GYE) and CNA w/ 5% sheeps blood agar (5%SB-CNA) inhibited the growth of Coccidioides, but that grown on chocolate agar does not. Partial depletion of the microbiota through antibiotic disk diffusion revealed that microbiota depletion leads to diminished inhibition and comparable growth of Coccidioides growth to controls. To characterize the bacteria grown and narrow down potential candidates contributing to the inhibition of Coccidioides, 16s rRNA sequencing of tracheal and intestinal agar cultures and murine lung extracts was performed. The identity of host bacteria that may be responsible for this inhibition was revealed. The results of this study demonstrate the potential of the host microbiota to inhibit the growth of Coccidioides in vitro and suggest that an altered microbiome through antibiotic treatment could negatively impact effective fungal clearance and allow a niche for fungal growth in vivo. ImportanceCoccidioidomycosis is caused by a fungal pathogen that invades host lungs, causing respiratory distress. In 2019, 20,003 cases of Valley fever were reported to the CDC. However, this number likely vastly underrepresents the true number of Valley fever cases as many go undetected due to poor testing strategies and lack of diagnostic models. Valley fever is also often misdiagnosed as bacterial pneumonia, resulting in 60-80% of patients being treated with antibiotics prior to accurate diagnosis. Misdiagnosis contributes to a growing problem of antibiotic resistance and antibiotic induced microbiome dysbiosis, and the implications on disease outcome are currently unknown. 5%-10% of symptomatic Valley fever patients develop disseminated and/or chronic disease. Valley fever causes a significant financial burden and reduced quality of life. Little is known regarding what factors contribute to the development of chronic infection and treatments for disease are limited.

microbiology↗

bioRxiv2020

Single amino acid mutations effect Zika virus replication in vitro and virulence in vivo

The 2014-2016 Zika virus (ZIKV) epidemic in the Americas resulted in large deposits of next-generation sequencing data from clinical samples. This resource was mined to identify emerging mutations and trends in mutations as the outbreak progressed over time. Information on transmission dynamics, prevalence and persistence of intra-host mutants, and the position of a mutation on a protein were then used to prioritize 544 reported mutations based on their ability to impact ZIKV phenotype. Using this criteria, six mutants (representing naturally occurring mutations) were generated as synthetic infectious clones using a 2015 Puerto Rican epidemic strain PRVABC59 as the parental backbone. The phenotypes of these naturally occurring variants were examined using both cell culture and murine model systems. Mutants had distinct phenotypes, including changes in replication rate, embryo death, and decreased head size. In particular, a NS2B mutant previously detected during in vivo studies in rhesus macaques was found to cause lethal infections in adult mice, abortions in pregnant females, and increased viral genome copies in both brain tissue and blood of female mice. Additionally, mutants with changes in the region of NS3 that interfaces with NS5 during replication displayed reduced replication in the blood of adult mice. This analytical pathway, integrating both bioinformatic and wet lab experiments, provides a foundation for understanding how naturally occurring single mutations affect disease outcome and can be used to predict the of severity of future ZIKV outbreaks. Author summaryTo determine if naturally occurring individual mutations in the Zika virus epidemic genotype effect viral virulence or replication rate in vitro or in vivo, we generated an infectious clone representing the epidemic genotype of stain Puerto Rico, 2015. Using this clone, six mutants were created by changing nucleotides in the genome to cause one to two amino acid substitutions in the encoded proteins. The six mutants we generated represent mutations that differentiated the early epidemic genotype from genotypes that were either ancestral or that occurred later in the epidemic. We assayed each mutant for changes in growth rate, and for virulence in adult mice and pregnant mice. Three of the mutants caused catastrophic embryo effects including increased embryonic death or significant decrease in head diameter. Three other mutants that had mutations in a genome region associated with replication resulted in changes in in vitro and in vivo replication rates. These results illustrate the potential impact of individual mutations in viral phenotype.

microbiology↗