Research progress into the principles and methods underlying capsular typing of Glaesserella parasuis

Area of Science:

• Veterinary Microbiology
• Immunology
• Bacteriology

Background:

• Glaesserella parasuis (GPS) causes Glässer's disease in swine, a significant economic concern.
• Serotype identification of GPS has historically been a challenge, hindering research and control efforts.
• Previous methods like gel immunodiffusion (GID) and indirect hemagglutination assay (IHA) had limitations in typing efficiency and identifying all strains.

Purpose of the Study:

• To systematically review the historical development and application of GPS typing methods.
• To elucidate the shared antigenic basis underlying GID, IHA, and PCR typing.
• To provide insights into the immunology and principles of these methods for improved Glässer's disease prevention and control.

Main Methods:

• Review of historical serotyping techniques: GID (1992), IHA (2003).
• Analysis of capsular polysaccharide (CPS) gene clusters (2013).
• Development and evaluation of PCR-based typing methods (H-PCR in 2015, J-PCR in 2017).

Main Results:

• GID and IHA methods identified serotypes based on heat-stable or saline-extracted antigens but struggled with non-typeable strains (25% and 15% respectively).
• Capsular polysaccharides (CPS) were confirmed as essential antigens for serotyping.
• Combined PCR methods (H-PCR and J-PCR) enabled typing of nearly all GPS strains, demonstrating high consistency with GID and IHA.

Conclusions:

• The GPS capsule is the common antigenic basis for GID, IHA, and PCR typing.
• PCR typing methods offer significant advantages in speed, cost-effectiveness, and accuracy over traditional methods.
• Advanced PCR techniques represent a breakthrough in overcoming previous limitations in GPS serotyping, aiding disease control.