Immunological Responses and Control Strategies for Haemophilus Parasuis Infections

Haemophilus parasuis, the causative agent of Glässer’s disease in pigs, elicits a complex interplay of innate and adaptive immune responses. Upon colonisation of the upper respiratory tract, epithelial cells and alveolar macrophages recognise bacterial components via pattern recognition receptors, triggering NF-κB–mediated transcription of pro-inflammatory cytokines and activation of the NLRP3 inflammasome. Virulent strains evade clearance by expressing surface proteins such as VtaA autotransporters, which delay phagosome maturation, and outer membrane proteins that promote adhesion and biofilm formation. Adaptive immunity centres on the generation of strain-specific antibodies, often targeting linear B-cell epitopes within outer membrane proteins such as OmpP2. Control strategies combine antimicrobial therapy with improved diagnostics, including multiplex quantitative PCR assays that detect both species and virulence markers, and vaccination approaches informed by pan-genome analyses to identify conserved protective antigens. Novel adjunct therapies, such as plant-derived compounds that modulate inflammatory signalling, offer promise in reducing tissue damage and limiting antibiotic use. Ongoing research seeks to integrate molecular diagnostics, targeted vaccines and host-directed interventions to mitigate economic losses in global swine production.

Research from Nature Portfolio

Investigations using porcine aortic vascular endothelial cells have demonstrated that the flavonoid baicalin markedly suppresses H. parasuis–induced inflammatory responses by inhibiting both NF-κB activation and NLRP3 inflammasome assembly. Treatment reduced reactive oxygen species production, prevented apoptosis and attenuated expression of key cytokines, highlighting host-directed anti-inflammatory therapy as a complementary approach to traditional antimicrobials. Furthermore, this work established primary vascular endothelial cells as a robust in vitro model for studying host–pathogen interactions and screening novel immunomodulators.

Immunological Responses and Control Strategies for Haemophilus Parasuis Infections publication trend

The graph below shows the total number of articles in immunological responses and control strategies for haemophilus parasuis infections across all publications each year (not limited to Nature Index journals).

Technical terms

NF-κB signalling pathway: a transcription factor cascade controlling pro-inflammatory gene expression in response to microbial stimuli.

NLRP3 inflammasome: a multi-protein complex that activates inflammatory cytokines IL-1β and IL-18 upon recognition of pathogen-associated signals.

B-cell epitope: a specific peptide segment of an antigen recognised by B lymphocytes to initiate antibody production.

Pan-genome: the complete set of genes found across all strains of a species, including core genes shared by all and accessory genes present in subsets.

Multiplex quantitative PCR (qPCR): a molecular method that concurrently amplifies and quantifies multiple DNA targets to detect pathogens and assess virulence traits.

References

1. Screening of linear B-cell epitopes and its proinflammatory activities of Haemophilus parasuis outer membrane protein P2. Frontiers in Cellular and Infection Microbiology (2023).
2. Pan-genome wide association study of Glaesserella parasuis highlights genes associated with virulence and biofilm formation. Frontiers in Microbiology (2023).
3. Development of a new multiplex quantitative PCR for the detection of Glaesserella parasuis, Mycoplasma hyorhinis, and Mycoplasma hyosynoviae. MicrobiologyOpen (2023).
4. VtaA8 and VtaA9 from Haemophilus parasuis delay phagocytosis by alveolar macrophages. Veterinary Research (2012).
5. Baicalin modulates NF-κB and NLRP3 inflammasome signaling in porcine aortic vascular endothelial cells Infected by Haemophilus parasuis Causing Glässer’s disease. Scientific Reports (2018).