A phase trial of the oral Lactobacillus casei vaccine polarizes Th2 cell immunity against transmissible gastroenteritis coronavirus infection

Abstract

Transmissible gastroenteritis coronavirus (TGEV) is a member of the genus Coronavirus, family Coronaviridae, order Nidovirales. TGEV is an enteropathogenic coronavirus that causes highly fatal acute diarrhoea in newborn pigs. An oral Lactobacillus casei (L. casei) vaccine against anti-transmissible gastroenteritis virus developed in our laboratory was used to study mucosal immune responses. In this L. casei vaccine, repetitive peptides expressed by L. casei (specifically the MDP and tuftsin fusion protein (MT)) were repeated 20 times and the D antigenic site of the TGEV spike (S) protein was repeated 6 times. Immunization with recombinant Lactobacillus is crucial for investigations of the effect of immunization, such as the first immunization time and dose. The first immunization is more important than the last immunization in the series. The recombinant Lactobacillus elicited specific systemic and mucosal immune responses. Recombinant L. casei had a strong potentiating effect on the cellular immunity induced by the oral L. casei vaccine. However, during TGEV infection, the systemic and local immune responses switched from Th1 to Th2-based immune responses. The systemic humoral immune response was stronger than the cellular immune response after TGEV infection. We found that the recombinant Lactobacillus stimulated IL-17 expression in both the systemic and mucosal immune responses against TGEV infection. Furthermore, the Lactobacillus vaccine stimulated an anti-TGEV infection Th17 pathway. The histopathological examination showed tremendous potential for recombinant Lactobacillus to enable rapid and effective treatment for TGEV with an intestinal tropism in piglets. The TGEV immune protection was primarily dependent on mucosal immunity.

Immune response characterization of mice immunized with Lactobacillus plantarum expressing spike antigen of transmissible gastroenteritis virus

“…It is notable that the mucosal immune response is the first barrier to functionally neutralizing TGEV. The obtained results are in agreement with Jiang et al (2016).…”

Oral Immunization against PEDV with Recombinant Lactobacillus casei Expressing Dendritic Cell-Targeting Peptide Fusing COE Protein of PEDV in Piglets

“…The piglets received pPG-COE-DCpep/L393 or phosphate-buffered saline (PBS) alone in a different vaccination programs via an oral route, with 10 10 /mL colony-forming units (CFU) (for pPG-COE-DCpep/L393) in PBS. The immunization program was based on previous research on dosage and time points for immunization with recombinant Lactobacillus in piglets [15]; Group A (1 mL pPG-COE-DCpep/L393/Day 0); Group B (2 mL pPG-COE-DCpep/L393/Day 0); Group C (2 mL pPG-COE-DCpep/L393/Day 2); Group D (4 mL pPG-COE-DCpep/L393/Day 2); Group E (1 mL PBS). Groups A and B received an oral vaccine with different dosages of pPG-COE-DCpep/L393 immediately after birth.…”

Recombinant Lactobacillus casei Expressing Capsid Protein VP60 can Serve as Vaccine Against Rabbit Hemorrhagic Disease Virus in Rabbits

“…Currently, there is increasing interest in the development of L. casei oral vaccines, and this approach is significant for the effective induction of a mucosal immune response [30]. The results to date have been confirmed that the safety and the effectiveness of L. casei were used as the oral vaccine vehicle, which were extensively used in protecting individuals against a variety of pathogens [31][32][33][34][35][36][37].…”