A universal live vaccine platform against multiple serotypes Streptococcus suis based on polyvalent antigen protein

Area of Science:

• Veterinary Medicine
• Microbiology
• Immunology

Background:

• Streptococcus suis (S. suis) is a significant swine pathogen and an emerging cause of human meningitis.
• Current S. suis vaccines are limited, with no universal vaccine available to target multiple serotypes.
• Foodborne transmission of S. suis presents a growing public health concern.

Purpose of the Study:

• To develop a universal live vaccine candidate against multiple S. suis serotypes.
• To utilize a live Salmonella Choleraesuis (S. Choleraesuis) vector for antigen delivery.
• To evaluate the efficacy of the polyvalent antigen SE6 delivered by the vector.

Main Methods:

• Engineered a live S. Choleraesuis vector to express the polyvalent SE6 antigen.
• Administered the SE6-delivering S. Choleraesuis vector to mice for immunization.
• Assessed the opsonophagocytic activity of antisera against various S. suis serotypes.
• Challenged immunized mice with virulent S. suis serotypes 2, 7, and 9 to evaluate protection.

Main Results:

• Efficient expression and lymphatic delivery of the SE6 antigen by the S. Choleraesuis vector.
• Antisera from immunized mice showed potent opsonophagocytic responses against multiple S. suis serotypes.
• The SE6-delivering S. Choleraesuis vector provided significant protection against S. suis serotypes 2, 7, and 9 challenge.

Conclusions:

• The developed live S. Choleraesuis vector expressing SE6 is a promising universal vaccine candidate for S. suis.
• This strategy offers a potential solution for controlling S. suis in both animal and human populations.
• Further research is warranted to explore the broad applicability of this vaccine approach.