Brucella melitensis B115-based complement fixation test to detect antibodies induced by Brucella rough strains

Area of Science:

• Veterinary Microbiology
• Immunology
• Public Health

Background:

• Brucellosis remains a significant zoonotic disease, often caused by Brucella strains with a rough phenotype.
• Current diagnostic methods for antibodies against rough Brucella strains can be limited by antigen anticomplementary activity.
• Brucella melitensis B115 is a rough strain naturally lacking anticomplementary activity.

Purpose of the Study:

• To evaluate the efficiency of Brucella melitensis B115 as an antigen in complement fixation tests (CFT).
• To detect antibodies induced by rough Brucella strains, including Brucella abortus RB51, Brucella ovis, and Brucella canis.
• To assess the diagnostic performance of B115-based CFT compared to other antigens.

Main Methods:

• Complement fixation testing (CFT) was conducted using sera from animals infected or vaccinated with rough Brucella strains.
• Antigens tested included Brucella melitensis B115, Brucella abortus RB51, and hot saline extract (HSE).
• Sera originated from RB51-vaccinated cattle and buffaloes, B. ovis-infected sheep, and B. canis-infected dogs.

Main Results:

• The B115-based CFT demonstrated high sensitivity and specificity in detecting antibodies against rough Brucella strains.
• The diagnostic efficiency of the B115-based CFT was comparable to that of RB51 and HSE-based CFTs.
• The absence of anticomplementary activity in B115 simplifies antigen preparation and standardization.

Conclusions:

• Brucella melitensis B115 is a suitable and effective antigen for CFT in detecting antibodies induced by rough Brucella strains.
• The B115 antigen offers an improvement for Brucella antibody detection, enhancing brucellosis surveillance efficiency.
• B115-based CFT can serve as a valuable supplementary diagnostic tool for human brucellosis caused by rough Brucellae.