Thatcha Yimthin

Bacterial genetic variation contributes to the outcome of infection, but its relationship with host immune responses is rarely investigated in the same patients, limiting the biological interpretation of pathogen-associated disease severity. Here, we integrated pathogen genomics, clinical outcomes and host transcriptomics to investigate host-pathogen interactions in melioidosis, a frequently fatal infection caused by Burkholderia pseudomallei . We analysed prospective clinical data from 2,142 patients, whole-genome sequences from 2,101 infecting isolates and 646 paired host blood transcriptomes across five cohorts collected between 2012 and 2023. Infections were typically dominated by a single strain, with limited within-host diversification, supporting the use of an infecting isolate genome to investigate pathogen- associated clinical outcomes. Bacterial genome-wide association studies identified one locus associated with binary mortality at genome-wide significance. Incorporating patient age, sex, body mass index and Charlson Comorbidity Index increased this to four, while modelling time to death as a continuous phenotype identified seven loci. Integration with paired host transcriptomes linked mortality-associated bacterial genetic variation to imputed signatures of increased immature neutrophils and reduced neutrophil degranulation. An intergenic region upstream of the polyketide synthesis locus BPSS1006 - BPSS1011 was additionally associated with downregulation of host genes involved in myeloid-cell signalling and cell proliferation pathways. These findings connect naturally occurring B. pseudomallei genomic variation associated with mortality to distinct host immune signatures, providing insight into pathogen- host interactions underlying severe melioidosis and a framework for investigating the contribution of pathogen genetic diversity to clinical outcomes.

In June 2026 a bovine disease characterized by high fever, diarrhea and reduced milk production was reported in different European countries including France, Germany and Switzerland. The disease has been linked to an orthobunyavirus from the Simbu serogroup named Shamonda virus (SHAV). Later, a second novel SHAV clade has been reported. These strains are genomically different and have been designated to belong to the two clades SHAV-EU1 and SHAV-EU2. Abortions and embryos with congenital malformations have been reported in cattle infected with SHAV. Here we comprehensively evaluated the bovine immune responses to the SHAV isolate DE/2026 belonging to clade SHAV-EU1 using a blood-based ex vivo platform. To obtain insights into immune reactivity to bovine-adapted vector-borne viruses we included into our analysis Schmallenberg virus (SBV), a close relative of SHAV and bluetongue virus (BTV) serotype 8, a virus recently introduced in Europe. Interestingly, compared to SBV virus, SHAV induced a stronger proinflammatory response with abundant TNF-α, MIP-1β, IFN-γ and IL-1 release, and a significantly enhanced activation of most blood immune cell subsets. The fever-like temperature left immune responses to SHAV largely unchanged, in contrast to observations for vector-borne viruses such as SBV and BTV. These results are in line with the more pronounced clinical signs observed for the newly reported SHAV and indicate that closely related viruses trigger distinct immune cell activation which may contribute to disease pathophysiology.

Bovine digital dermatitis (BDD) is a globally distributed infectious hoof disease that negatively impacts the wellbeing and productivity of the affected animal. Treponema species and in particular Treponema phagedenis are the microbes strongly associated with the disease. Recently, it has been reported that Bos indicus cattle are more resistant to BDD and to the colonization by Treponema phagedenis in contrast to many Bos taurus breeds. This study investigated whether Bos indicus mount a different immune response to Treponema phagedenis compared with Bos taurus cattle, to better understand the different disease outcome in the two subspecies. Therefore, we exposed freshly isolated primary bovine blood cells to Treponema phagedenis and dissected subsequent bovine immune responses. The comparison between the two subspecies revealed significant different immune responses to Treponema phagedenis . We observed a stronger Th1/proinflammatory cytokine induction in Bos taurus animals mainly driven by CD4 ⁺ T and CD21 ^low B cells in secreting IFN-γ. We assume that these distinct initial immune responses are linked to the control of Treponema phagedenis and the outcome of BDD. Additionally, we observed significant higher levels in the expression of the matrix metalloproteinase-9 by peripheral blood mononuclear cells in Bos indicus cattle, which likely benefits the host response to Treponema phagedenis .

Cattle are the mammalian species with most global biomass, encompass the two subspecies Bos taurus and Bos indicus, which are phenotypically distinguishable and have distinct genetic backgrounds. We used fresh primary bovine blood cells to characterize and dissect host-pathogen interactions, hypothesizing that Bos taurus and Bos indicus cattle exhibit different immune responses towards vector-borne diseases (VBDs) impacting the clinical disease outcome. We tested Schmallenberg virus (SBV) and Bluetongue virus (BTV), examples of vector-borne pathogens responsible for recent European disease outbreaks, driven by increased vector activity linked to rising temperatures. Bos taurus cattle showed a moderate ex vivo response towards SBV compared to BTV (i.e., qualitative and magnitude changes in activation/maturation state of immune cells and cytokine secretions), which indicates a fine-tuning of the immune response depending on vector-borne virus. The most striking finding was the differential immune response towards BTV: broad and over-exuberant in Bos taurus (i.e., antiviral, cellular and humoral), mainly antiviral in Bos indicus. Moreover, fever-like temperature, a classical clinical sign of disease, reduced the capacity of most immune cell subsets to respond to the pathogens tested. Overall, our findings reinforce other studies that suggest different susceptibilities of the Bos indicus versus Bos taurus towards major pathogens.

Cattle are the mammalian species with most global biomass, encompass the two subspecies Bos taurus and Bos indicus , which are phenotypically distinguishable and have distinct genetic backgrounds as a result of their different evolutionary trajectories. We used fresh primary bovine blood cells to characterize and dissect host-pathogen interactions, hypothesizing that Bos taurus and Bos indicus cattle exhibit different immune responses towards vector-borne diseases (VBDs) impacting the clinical disease outcome. We tested Schmallenberg virus (SBV) and Bluetongue virus (BTV), examples of vector-borne pathogens responsible for recent European disease outbreaks, driven by increased vector activity linked to rising temperatures. Bos taurus cattle showed a moderate ex vivo response towards SBV compared to BTV, which indicates a fine-tuning of the immune response depending on vector-borne virus. The most striking finding was the differential immune response towards BTV: broad and over-exuberant in Bos taurus , mainly antiviral in Bos indicus . Moreover, fever-like temperature, a classical clinical sign of disease, reduced the capacity of most immune cell subsets to respond to the pathogens tested. Overall, our findings of different immune responses are in line with other studies that suggest different susceptibilities of the Bos indicus versus Bos taurus towards major pathogens like bovine tuberculosis.

The rising spread of antimicrobial resistance challenges animal welfare, productivity and food supply with respect to bacterial infections in different livestock species. Bacteriophages offer alternative means to control infections with resistant bacteria. This work investigated the host immune responses towards lytic bacteriophages K and T1, acting respectively on Gram-positive or Gram-negative bacteria. We employed an ex vivo platform to decipher various immune responses elicited by primary blood cells of eight outbred cattle. Bacteriophage K was not recognized whereas bacteriophage T1 induced a profound immune response. Therefore, prior characterization of host immune responses towards therapeutic phages should be considered before therapy starts.

Extracellular vesicles (EVs) are central components of bacterial secretomes, including the small, cell wall-less Mollicutes. Although EV release in Mollicutes has been reported, EV proteomic composition and function have not been explored yet. We developed a protocol for isolating EVs of the pathogens Mycoplasma mycoides subsp. capri (Mmc) and Mycoplasma (Mycoplasmopsis) bovis and examined their functionality. Proteomic analysis demonstrated that EVs mirror the proteome of the EV-producing bacteria. EVs exhibited nuclease activity, effectively digesting both circular and linear DNA. Notably, M. bovis EVs elicited immune responses in bovine primary blood cells, like those induced by live M. bovis. Our findings reveal that EVs can carry plasmids and enable their horizontal transfer, known as vesiduction. Specifically, the natural plasmid pKMK1, with an unknown transmission route, was detected in EVs of Mmc 152/93 and the tetM-containing pIVB08 plasmid was associated with EVs released by an Mmc GM12 strain carrying this plasmid. pIVB08 could be transferred via homo- and heterologous vesiduction to Mmc, M. capricolum subsp. capricolum and M. leachii. Vesiduction was impeded by membrane disruption but resisted DNase and Proteinase K treatment, suggesting that EVs protect their cargo. These findings enhance our understanding of Mollicutes EVs, particularly in host interactions and horizontal gene transfer.

Extracellular vesicles (EVs) are central components of bacterial secretomes, including the small, cell wall-less Mollicutes. Although EV release in Mollicutes has been reported, EV proteomic composition and function have not been explored yet. We developed a protocol for isolating EVs of the pathogens Mycoplasma mycoidessubsp. capri (Mmc) and Mycoplasma (Mycoplasmopsis)bovis and examined their functionality. Proteomic analysis demonstrated that EVs mirror the proteome of their homologous strain. EVs exhibited nuclease activity, effectively digesting both circular and linear DNA. Notably, EVs elicited immune responses in bovine primary blood cells, like those induced by live M. bovis. Our findings reveal that EVs can carry plasmids and enable their horizontal transfer, known as vesiduction. Specifically, the natural plasmid pKMK1, with an unknown transmission route, was detected in EVs of Mmc 152/93 and the tetM-containing pIV08 plasmid was associated with EVs released by an Mmc GM12 strain carrying this plasmid. pIVB08 could be transferred via homo- and heterologous vesiduction to Mmc, M. capricolum subsp. capricolum and M. leachii. Vesiduction was impeded by membrane disruption but resisted DNase and Proteinase K treatment, suggesting that EVs protect their cargo. These findings enhance our understanding of Mollicutes EVs, particularly in host interactions and horizontal gene transfer.

The Mycoplasma Immunoglobulin Binding/Protease (MIB-MIP) system is a candidate ‘virulence factor present in multiple pathogenic species of the Mollicutes, including the fast-growing species Mycoplasma feriruminatoris. The MIB-MIP system cleaves the heavy chain of host immunoglobulins, hence affecting antigen-antibody interactions and potentially facilitating immune evasion. In this work, using -omics technologies and 5’RACE, we show that the four copies of the M. feriruminatoris MIB-MIP system have different expression levels and are transcribed as operons controlled by four different promoters. Individual MIB-MIP gene pairs of M. feriruminatoris and other Mollicutes were introduced in an engineered M. feriruminatoris strain devoid of MIB-MIP genes and were tested for their functionality using newly developed oriC-based plasmids. The two proteins are functionally expressed at the surface of M. feriruminatoris, which confirms the possibility to display large membrane-associated proteins in this bacterium. However, functional expression of heterologous MIB-MIP systems introduced in this engineered strain from phylogenetically distant porcine Mollicutes like Mesomycoplasma hyorhinis or Mesomycoplasma hyopneumoniae could not be achieved. Finally, since M. feriruminatoris is a candidate for biomedical applications such as drug delivery, we confirmed its safety in vivo in domestic goats, which are the closest livestock relatives to its native host the Alpine ibex.