Brian Stevenson Ph.D. spirochete lab

@bstevensonlab

Mostly about bacterial gene/protein regulation & function, esp. with Borrelia burgdorferi and Lyme disease. Professor at U Kentucky, views are my own. He/him Lab= UK=

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Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 2d

You cannot rage against the machine if you’re asking it to summarize your emails for you

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 2d

Merging a hobby with my day job. I collect antique microscopes and microscope slides. The mid-to-late-1800s were a golden age of amateur microscopy. Numerous professionals prepared high-quality slides for that large market of hobbyists. "Ixodes from tortoise", prepared ca. 1890.

ca. 1890 microscope slide of a tick taken from a tortoise, and mounted by Ernest Hinton. Next to a magnified image of the tick (3.5x objective, C-mounted digital SLR camera, and transmitted light.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 3d

ospC diversity in Borrelia burgdorferi: different hosts are different niches A report from 2004 that also found that OspC type U preferentially infected chipmunks academic.oup.com/genetics/art... #MicroSky

Table from the paper.
The outer surface protein C (ospC) locus of the Lyme disease bacterium, Borrelia burgdorferi, is at least
an order of magnitude more variable than other genes in the species. This variation is classified into 22
ospC major groups, 15 of which are found in the northeastern United States. The frequency distributions
of ospC within populations suggest that this locus is under balancing selection. In multiple-niche polymor-
phism, a type of balancing selection, diversity within a population can be maintained when the environment
is heterogeneous and no one genotype has the highest fitness in all environments. Genetically different
individuals within vertebrate species and different vertebrate species constitute diverse environments for
B. burgdorferi. We examined four important host species of B. burgdorferi and found that the strains that
infected each species had different sets of ospC major groups. We found no variation among conspecific
hosts in the ospC major groups of their infecting strains. These results suggest multiple niches create
balancing selection at the ospC locus.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 3d

Diversity and host specificity of Borrelia burgdorferi’s outer surface protein C (ospC) alleles in synanthropic mammals, with a notable ospC allele U absence from mixed infections Does OspC type U preferentially infect chipmunks? And exclude other types? journals.asm.org/doi/epub/10.... #MicroSky

Figure 2
Heatmap showing ospC allele frequencies across host species (T. striatus, eastern chipmunk; S. carolinensis, eastern gray squirrel; Peromyscus, white-footed/deer mice; M. pennsylvanicus, eastern meadow vole; M. musculus, house mouse; M. mephitis, stripped skunk). Higher allele frequencies are redder and lower frequencies are bluer. Human infectious alleles (A, B, I, and K) are italicized and in bold font.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 3d

Curiouser and curiouser: understanding the intersection of inter- and intra-specific diversity during the Borrelia burgdorferi enzootic cycle and Lyme disease journals.asm.org/doi/10.1128/... #MicroSky

Fig 1 B. burgdorferi enzootic cycle and reservoir competence. (A) The B. burgdorferi enzootic cycle. Larval ticks (Ixodes) acquire B. burgdorferi during feeding on infected vertebrate hosts. These ticks molt to nymphs before feeding on uninfected hosts and transmitting the bacteria. During feeding, adult female ticks can also transmit the bacteria to reservoirs before completing the tick reproductive cycle and producing new, uninfected larval ticks. Reservoir hosts infected during nymphal and adult tick feeding can harbor the bacteria and, in turn, spread B. burgdorferi back into the tick population. (B) Reservoir competence depends on a variety of factors, including abundance of the host, host-tick interactions, and host-B. burgdorferi interactions (7). Additional complexity is added to the system as different hosts may be more or less competent for specific strains of B. burgdorferi (13, 14). Figure illustrated by Patrick Lane—ScEYEnce Studios.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 6d

A direct, urine-based test to diagnose acute Lyme disease using actively secreted peptidoglycan as a biomarker Exciting new results from @jutraslab.bsky.social www.medrxiv.org/content/10.6... #TheShowMustGoOn #MicroSky

Figure 1.
Monoclonal antibody cocktail specifically detect released Borreliae PG
(A) Each monoclonal antibody (mAb) were incubated with purified, enzyme-digested B. burgdorferi PG (dPG). Immunoprecipitation, coupled with quantitative LCMS, identified high-affinity interactions for four different mAb. Heat map indicates the percent of each muropeptide bound, relative to input control. (B) Cartoon schematic of the muropeptide structure bound by the mAbs in ‘A’. The numbers associated with each muropeptide species indicate enantomers or isobarics present in B. burgdorferi PG. (C) A cocktail of capture and detection mAb pairs is a sensitive approach to detect purified, dPG produced by B. burgdorferi. Values were background subtracted using the absorbance values of a PBS control. (D) The same cocktail of capture and detection mAb pairs provide high affinity binding to released B. burgdorferi PG in spent culture medium. B. burgdorferi were cultured to late-log, cells harvested, spent cultured media filtered (0.2 μm), and titrations were assayed by ELISA. Control reactions included sterile culture media, processed similarly, or the same sterile media spiked with dPG. (E) Lyme Borrelia spp. release PG. Each species was pulse labeled with 5uCi of 3H L-Orn for 2-3 generations, washed, and back-diluted into fresh media. Pre- and post-culture expansion, PG was purified and quantified by liquid scintillation. (F) The mAb cocktail cross-reacts with digested PG from different Lyme-disease causing Borrelia spp. Purified, dPG, attained from different Borrelia spp. was titrated into human urine (diluted 1:2 with PBS) and detected by ELISA. Values were background subtracted using the absorbance of a neat human urine diluted with PBS (1:2) that was not spiked with PG. Data points with absorbance of 4 were beyond the detection limit of the spectrophotometer.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 9d

Midwest Microbial Pathogenesis Conference (MMPC) September 25-27, 2026 University of Minnesota Minneapolis, MN Register now! #MicroSky

MMPC Tshirt design. Shows the shape of Minnesota, composed of bacteria and viruses

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 10d

In the Land of Cheese and Phages! #phages2026

Display of cheeses, and three Wisconsin “Cheesehead” hats

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 14d

Had a few drinks with my ghosts last night

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 15d

Devastated to report that Brandon Jutras passed away a day or two ago. Brandon earned his PhD with me. He went on to be an Associate Professor at Northwestern University School of Medicine and a super star in Lyme research. A loving husband and father, a sincere friend, and a brilliant scientist 💔

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 16d

Relapsing fever in Texas, USA Human Exposure to Spirochete-Infected Ornithodoros turicata in a Residential Setting in the Austin, Texas Metropolitan Area pubmed.ncbi.nlm.nih.gov/42517151/ #MicroSky

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· 27d

On the top of the University’s daily propaganda email ! uknow.uky.edu/research/res...

Screenshot of 7/17 UK Now, the daily propaganda email from the University of Kentucky. Shows an attractive, bearded scientist who is holding up a tick.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jul 10

Today we say goodbye to my parents’ mortal remains ❤️❤️

Two people kissing, within a large frame

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jul 8

Onion satire: picture of puzzled man with cell phone and computer, with caption:
“Study: 97% of average American’s day spent retrieving 6-digit codes”

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jul 6

Bought this bag of dried milk when I started my lab in 1998 (saved startup funds by buying generic). Finished it in 2024.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jul 1

Riboflavin Salvage Supports Glycolysis in Borrelia burgdorferi Through Flavin-Dependent NAD+ Regeneration Nifty new information from Mollie Jewett and team! onlinelibrary.wiley.com/doi/10.1111/... #MicroSky

Graphical Abstract

The Lyme disease agent Borrelia burgdorferi has limited metabolic capabilities and depends on salvage of riboflavin via the BB0316-BB0319 transport system for generation of critical flavin cofactors FMN and FAD. Riboflavin is important for NAD+ regeneration to fuel glycolysis. FAD-dependent coenzyme A disulfide reductase (CoADR) is the critical link between riboflavin availability and glycolytic redox balance driving glycolytic success in B. burgdorferi.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jul 1

Dermacentor again!

Video of feeding Dermacentor tick, from Uni of Nomi's Lyme disease page. Dermacentor ticks cannot vector Lyme disease

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jul 1

Friendly reminder to use photographs of Ixodes ticks when discussing Lyme disease. The illustrated Dermacentor spp. cannot vector Lyme disease 🤦🙄

Screen cap of U Nomi's opening page on Lyme disease. Shows a Dermacentor spp. tick, which cannot vector Lyme disease

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 25

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 24

Dr. Mark Martin's "Matters Microbial" podcasts @markowenmartin.bsky.social Watch 'em all! www.youtube.com/playlist?lis... #MicroSky

Screenshot of intro to "Matters Microbial"

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 24

The host calcium system contributes to intracellular Rickettsia pathogenesis "Calcium channel blockers (disrupt) rickettsial actin polymerization, and these results highlight the complex interdependence of Rickettsia and host cell biology." journals.asm.org/doi/10.1128/... #MicroSky

Figure 5 from the article:
CCB disruption of actin-based mobility. (A) Fluorescence micrographs of R. conorii and host actin after 48 hours of infection with noted compounds added for the last 24 hours of infection. R. conorii (green) containing actin tails (red) are readily observed in mock (DMSO) treated cells, but the frequency of actin polymerization is reduced in CCB and Cytochalasin D treated cells. (B) Quantification of R. parkeri with observable actin tails after 48 hours of infection of EA.hy926 cells with noted compounds. Treatment with all three CCBs and the actin polymerization inhibitor Cytochalasin D all significantly reduced rickettsial actin polymerization. (C) Similar analysis of actin polymerization in R. conorii-infected EA.hy926 cells. Scale bar = 20 µm. *P < 0.05 by one-way ANOVA with Dunnett’s multiple comparisons test.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 22

Machine learning-driven identification of virulence determinants in Borrelia burgdorferi associated with human dissemination New publication from @brissettelab.bsky.social journals.plos.org/ploscompbiol... #MicroSky

Fig 1. Overview of machine learning workflow.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 22

Structural architecture of a hybrid β-barrel assembly machinery BAM-TAM complex in Borrelia burgdorferi More cool structural information of the Lyme disease spirochete, from Kalvis Brangulis! www.sciencedirect.com/science/arti... #MicroSky

From the paper:

Figure 1. (A) Structure of the E. coli BAM complex (PDB ID: 9HG9) showing BamA (grey), BamB (orange), BamD (brown), BamC (green) and BamE (purple). (B) AlphaFold-predicted structure of B. burgdorferi BamA (residues 25-821; average predicted local-distance difference test (pLDDT) value of 86.1) superimposed with BamA from E. coli (Uniprot: P0A940; gold; average pLDDT 92.5; Cα root-mean-square deviation (RMSD) of 3.5 Å). Both proteins are illustrated without the N-terminal signal sequence, and the 16-stranded β-barrel of B. burgdorferi BamA is colored grey, while the periplasmic POTRA domains are colored as follows: POTRA1 (residues 28-102), red; POTRA2 (residues 103-180), green; POTRA3 (residues 181-275), blue; POTRA4 (residues 276-353), purple; and POTRA5 (residues 354-430), orange. (C) Superimposed B. burgdorferi POTRA domains 1-5 (RMSD 1.63 to 3.05 Å).

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 15

Infection with multiple strains of the Lyme disease bacterium in female mice can affect the strain-specific maternal antibody response in their offspring www.sciencedirect.com/science/arti... #MicroSky

From the publication:
Fig. 2. Experimental design of the study. At 7 weeks of age, 32 female mice were randomly assigned to one of four groups (n = 8 mice per group): (1) uninfected (white), (2) infected with B. burgdorferi strain A (red), (3) infected with B. burgdorferi strain I (blue), and (4) co-infected with both strains (purple). Female mice were infected via nymphal tick bite; uninfected females were infested with uninfected nymphs. At 10 weeks of age and at 3 weeks post-infection, female mice were mated with uninfected male mice. At 13-14 weeks of age and at 6-7 weeks post-infection, female mice produced 139 offspring. At weeks 1 and 2 of age, mouse pups were euthanized (n = 47), exsanguinated, and milk was obtained from their stomachs. A total of 88 offspring were weaned and were assigned to group 1 (G1; n = 45 offspring) and group 2 (G2; n = 43 offspring). The G1 pups and G2 pups were challenged with both B. burgdorferi strains via nymphal tick bite at 6 weeks of age and at 11 weeks of age, respectively.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 14

To Move or Not to Move: When and How Bacteria Suppress Flagellar Motility onlinelibrary.wiley.com/doi/full/10.... #MicroSky

Graphical Abstract

Motility cessation in bacteria is a key regulatory strategy that provides multiple survival advantages including enhanced community cooperation, niche adaptation and evasion of host immune responses. This process is controlled by associated mechanisms such as post-translational modifications and second messenger signalling that stabilise non-motile bacterial attachment. This review aims to provide a comprehensive overview of the molecular mechanisms in motility suppression and the functional and environmental conditions that trigger the transition from motile to non-motile states.

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 13

Wash cycle complete! At the Institute for Cancer Research / Royal Marsden Hospital with @generoom.bsky.social

Two sciency-guys standing next to a multimillion dollar washing machine.
(Actually, a high throughput DNA sequencer)

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 12

When Clades Collide: Genomic Admixture in Blacklegged Ticks (Ixodes scapularis) from the Great Plains "~50% infection rate (of B. burgdorferi) in ticks from Iowa and northeastern Nebraska, whereas ticks from Kansas show no evidence of B. burgdorferi infection" www.biorxiv.org/content/10.6...

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 11

Borrelia host adaptation Regulator (BadR) regulates rpoS to modulate host adaptation and virulence factors in Borrelia burgdorferi Miller, Karna, and Seshu onlinelibrary.wiley.com/doi/10.1111/... #MicroSky

Model from the paper (current data suggest that this is probably not completely accurate)
Figure 8
BadR represses rpoS to regulate host-specific adaptation in B. burgdorferi. The rpoS gene is upregulated in a badR-deficient B. burgdorferi strain. Log2 fold change of rpoS derived from two microarrays from (pH 7.6/32°C) grown cultures. P-values from pooled (overall) and individual arrays (Rep.1, Rep.2) are indicated using n = 4 for both A3 (WT) and badR− (A). Quantitative RT-PCR fold changes of rpoS are indicated with P ≤ 0.01. Error bars indicate s.e.m. (B). Predicted BadR regulatory network. Many activators of rpoS have been identified (e.g. DsrABb, BosR, RpoN, RpoD, CsrABb). Our study is the first to demonstrate BadR as a repressor of rpoS and thus may facilitate the spirochaete's transition back into ticks. A model for BadR regulation entails the following: 1.) BadR binds upstream of rpoS to repress rpoS in unfed ticks; 2.) Since ROK regulators are nutrient-responsive, BadR regulation may be modulated directly or indirectly by nutrient inducers; 3.) Nutrient surges from the blood meal may provide the inducer to allow BadR's derepression of rpoS; and 4.) BadR regulates chitobiose utilization genes and may activate genes to enhance the spirochaetes maintenance in ticks (lp28-4 genes). Square = activation, oval = repression by BadR respectively (C).

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· Jun 8

On Borrelia burgdorferi lipids: A lipid compendium of a metabolically compromised bacterium provides insights into lipid acquisition, biosynthesis, and metabolism www.biorxiv.org/content/10.6... #MicroSky

From the Preprint:
Fig. 2. Neutral lipids in B. burgdorferi. (A, B) Sankey diagrams illustrating
the relative abundance of neutral lipids identified via tandem mass
spectrometry. The width of each flow is proportional to the integrated peak area under the curve of the daughter ion, with the distribution of
cholesteryl esters (ChE, A) and triglycerides (TG, B). (C, D) Widefield
epifluorescence microscopy images of fixed B. burgdorferi cells show
lipid staining with either the neutral lipid-specific LipidTOXTM (C) or the
non-specific dye Nile Red (D). Scale bar = 5 μm

Brian Stevenson Ph.D. spirochete lab@bstevensonlab· May 11

The wild, wild west of plasmids: First insights into comparative genomics of Borrelia burgdorferi sensu lato journals.plos.org/plosone/arti... pubmed.ncbi.nlm.nih.gov/42102105/ #MicroSky