Haemophilus parasuis VtaA2 is involved in adhesion to extracellular proteins

Abstract

Haemophilus parasuis is part of the microbiota of the upper respiratory tract in swine. However, virulent strains can cause a systemic disease known as Glässer’s disease. Several virulence factors have been described in H. parasuis including the virulence-associated trimeric autotransporters (VtaAs). VtaA2 is up-regulated during infection and is only found in virulent strains. In order to determine its biological function, the vtaA2 gene was cloned with its native promotor region in pACYC184, and the transformed Escherichia coli was used to perform functional in vitro assays. VtaA2 was found to have a role in attachment to plastic, mucin, BSA, fibronectin and collagen. As other VtaAs from H. parasuis, the passenger domain of VtaA2 contains collagen domains. In order to examine the contribution of the collagen repeats to VtaA2 function, a recombinant vtaA2 without the central collagen domains was obtained and named vtaA2OL. VtaA2OL showed similar capacity than VtaA2 to adhere to plastic, mucin, BSA, fibronectin and plasma but a reduced capacity to adhere to collagen, suggesting that the collagen domains of VtaA2 are involved in collagen attachment. No function in cell adhesion and invasion to epithelial alveolar cell line A549 or unspecific binding to primary alveolar macrophages was found. Likewise VtaA2 had no role in serum or phagocytosis resistance. We propose that VtaA2 mediates adherence to the host by binding to the mucin, found in the upper respiratory tract mucus, and to the extracellular matrix proteins, present in the connective tissue of systemic sites, such as the serosa.

Sow Vaccination with a Protein Fragment against Virulent Glaesserella (Haemophilus) parasuis Modulates Immunity Traits in Their Offspring

“…However, commercial bacterins do not provide protection against all G. parasuis strains, promoting the search for alternative vaccines that could confer cross-protection among virulent strains of different serovars. Several vaccine candidates have been proposed in the literature [4], including virulence factors such as the virulenceassociated trimeric autotransporters (VtaA), which are involved in phagocytosis resistance [5] and adhesion to extracellular matrix proteins [6]. In a previous study from our group, immunization with a combination of six VtaA proteins provided partial protection against a lethal infection with a virulent G. parasuis strain in colostrum deprived piglets [7].…”

Integrative gene network analysis identifies TIMP1 as key factors for Haemophilus parasuis infection

“…TIMP1 is a glycoprotein belonging to the member family of Tissue inhibitor of metalloproteinase and is an endogenous inhibitor of matrix metalloproteinases (MMPs) 14 to regulates the extracellular matrix (ECM) turnover and remodelling during normal development and pathogenesis. The virulence-associated trimeric autotransporters (VtaAs) in H.parasuis was found containing collagen domains and binding to extracellular matrix proteins for adherence to the host 15 . In addition, TIMP1 has been identi ed to be bene cial for vascular integrity and can interact with CD63/integrin β 1 complex and regulate FAK/RhoA signaling to protect blood-brain barrier function 16 .…”

“…In addition, TIMP1 has been identi ed to be bene cial for vascular integrity and can interact with CD63/integrin β 1 complex and regulate FAK/RhoA signaling to protect blood-brain barrier function 16 . The virulence-associated trimeric autotransporters (VtaAs) in H.parasuis was found containing collagen domains and binding to extracellular matrix proteins for adherence to the host 17 . Moreover, TIMP1 also plays an important role of anti-in ammatory and antinociceptive 18 , indicating that TIMP1 may be a critical component of a signalling cascade involved in reducing in ammatory hypersensitivity.…”

Glaesserella parasuis serotype 4 HPS4-YC disrupts the integrity of the swine tracheal epithelial barrier and facilitates bacterial translocation

“…Glaesserella parasuis ( G. parasuis ), the causative agent of Glässer disease, is a Gram-negative opportunistic bacterial pathogen that colonizes the upper respiratory tract of pigs. G. parasuis infection induces severe systemic inflammatory reactions characterized by fibrinous polyserositis, pneumonia, arthritis and meningitis, resulting in extensive economic losses for the pig industry [ 1 , 2 ]. To date, 15 serotypes of G. parasuis have been defined, in addition to nontypeable isolates.…”