Veterinary Epidemiology and Zoonosis

ABORTUS BANG RING TEST

Diagnosis of brucellosis by abortus bang ring test

• Brucella milk ring antigen is stained with red tetrazolium dye.
• Presence of agglutinins in milk aggregates fat globules. Addition of red coloured stained Brucella cells causing formation of antibrucella antibody-fat globule complex, which rise to the top of the test tube to form a red coloured cream ring.
• The first objective is to detect the infected herd.
• A pooled milk sample is tested from the herd. If a herd is found positive then all the cattle in that herd are tested individually.
• For herd test using milk, milk ring test is performed. This test is usually performed 3 or 4 times a year. Milk samples are to be mixed well using a plunger before sample is taken.

Materials required

Materials required	Quantity and purpose
Abortus Bang ring test antigen (coloured)	30µL per sample
Known brucella positive and negative serum	Each 30µL per test
Pooled milk samples suspected for brucellosis	10 mL per test. Collect milk samples and add preservative: 0.5mL of preservative (7.5mL 37 % formaldehyde in 1 litre of distilled water) to every 10 ml of milk sample
Test tube, Test tube rack, Pipette Micropipette and Microtips	Adequate numbers

Procedure

• Take 2mL of milk in the test tube.
• Add 30µL of Abortus bang ring test antigen (coloured) with the help of pipette.
• Shake the mixture by rotating in between palm for one minute.
• Incubate at 37 ° C for 1 hour.
• After incubation, allow the test tube to stand. Then read the result.
• Always keep positive and negative controls.

Figure: Abortus Bang ring test (ABRT)

Interpretation of result

Cream colour	Milk colour	Result
Deep cherry colour	White colour	+++++ (5+)
Definitely coloured	Slightly coloured	+++ (3+)
Cream ring	Moderately coloured	++ (2+)
White / slightly coloured	Milk sample is uniformly pink in colour, without ring formation	Negative