Evaluation of immunogenicity and protective efficacy of recombinant outer membrane proteins of Haemophilus parasuis serovar 5 in a murine model

Abstract

Glässer’s disease is an economically important infectious disease of pigs caused by Haemophilus parasuis. Few vaccines are currently available that could provide effective cross-protection against various serovars of H. parasuis. In this study, five OMPs (OppA, TolC, HxuC, LppC, and HAPS_0926) identified by bioinformatic approaches, were cloned and expressed as recombinant proteins. Antigenicity of the purified proteins was verified through Western blotting, and primary screening for protective potential was evaluated in vivo. Recombinant TolC (rTolC), rLppC, and rHAPS_0926 proteins showing marked protection of mice against H. parasuis infection, and were further evaluated individually or in combination. Mice treated with these three OMPs produced humoral and host cell-mediated responses, with a significant rise in antigen-specific IgG titer and lymphoproliferative response in contrast with the mock-immunized group. Significant increases were noted in CD4+, CD8+ T cells, and three cytokines (IL-2, IL-4, and IFN-γ) in vaccinated animals. The antisera against candidate antigens could efficiently impede bacterial survival in whole blood bactericidal assay against H. parasuis infection. The multi-protein vaccine induced more pronounced immune responses and offered better protection than individual vaccines. Our findings indicate that these three OMPs are promising antigens for the development of multi-component subunit vaccines against Glässer's disease.

Evaluation of the recombinant proteins RlpB and VacJ as a vaccine for protection against Glaesserella parasuis in pigs

“…parasuis vaccine development has suffered from difficulty generating a broadly cross-protective vaccine. Many platforms have been attempted: whole cell bacterins, outer-membrane vesicles, live avirulent strains, and a variety of subunit vaccines [5,6,13,15,[24][25][26][27]. While homologous protection with whole cell vaccines is often high, those studies investigating heterologous protection show less efficacy [7][8][9][10].…”

“…Several mechanisms have been employed to identify subunit vaccine candidates, including the use of hyperimmune or post-challenge serum from pigs to identify proteins separated by gel electrophoresis and in silico prediction methods [13][14][15]. In this report, we utilized a previously reported functional genomic screen to identify subunit vaccine candidates [16].…”

Molecular Serotyping and Resistance of Clinical Strains of Haemophilus (Glaesserella) Parasuis in Chinese Pig Farms From 2016 to 2018.

“…Most Clinical studies had shown that the protection of inactivated vaccine was mainly against isolates of the same serovars, and its cross-protection was extremely limited (10), for this reason, choosing inactivated vaccines of local epidemic serotypes was more bene cial to defend against H. parasuis. In different regions and a combination of protective antigens might be able to provide effective protection against multiple H. parasuis serovars (23).…”

“…14/220) are successively reduced. In 2017, Guangdong Province accounted for the highest separation rate(16.11%, 168/1043), followed by Shandong Province (12.5%,23/184) and Hunan Province (12.03%, 35/291), then the separation rate of Guangxi Province (11.88%, 12/101), Hubei Province (8.8%, 161/1829), Henan Province (8.58%, 79/921), Sichuan Province (7.41%, 16/216), Fujian Province (6.06, 12/198), Anhui Province (5.04%, 7/139), Shaanxi Province (4.23%, 3/71), Jiangsu Province (4.1%, 5/122) and Shanxi Province (3.92%, 2/51) decreased in turn. In 2018, Zhejiang Province accounted for the highest separation rate (20.34%, 12/59), followed by Guangdong Province (13.11%, 110/839), Besides, the separation rate of Fujian Province (10.98%, 19/173), Guangxi Province (9.02%, 12/133), Henan Province (7.58%, 75/990), Hunan Province (7.14%, 12/168), Hubei Province (5.41%, 91/1682) and Shandong Province (5.17%, 6/116) decreased in turn.…”

Transcriptomics of Haemophilus (Glässerella) parasuis serovar 5 subjected to culture conditions partially mimetic to natural infection for the search of new vaccine antigens

“…The upregulated gene tolC found in this study encodes an Omp (TolC) lipoprotein that forms a trimeric channel and acts in the transport of several molecules [ 32 ]. Li et al [ 33 ] observed that mice immunized with this protein and then challenged with H. ( G. ) parasuis showed a survival rate of 80%.…”