Usage of BIV antigen to detect latent forms of brucellosis in the cattle

Today conventional means of brucellosis control include timely conducted diagnostic tests, removal of animals with positive response and administration of brucellosis vaccines. 

Below you will find brief information about the brucellosis vaccines most of which have been produced at our bio factory:
Live freeze-dried vaccine in S-form prepared from strain 19, vaccine in SR-form prepared from strain 82, in R-form - from strain 75/79. Also there is an inactivated emulsified vaccine in R-form prepared from strain 17/100 KB. All the vaccines provide 60-100% protection. Live vaccines are considered to be more immunogenic. However, all vaccines have some weaknesses.
The vaccine from strain 19 protects animals against abortion. However, its high agglutinogenicity significantly diminish its qualities. A study conducted on the timely vaccinated cattle revealed a large numbers of animals (especially cows) with positive response. Moreover, being long-term (5 to 8 years), such response made it impossible to differentiate serologically vaccinated animals from infected with field strains.
In this respect the vaccine prepared from strain 82 is the most preferable. Three months after its application it doesn’t show agglutinogenic reactions, at the same time, it causes abortions in heifers.
The vaccine from strain 75/79 is neither abortogenic nor induces long-term titers, but its immunogenicity is lower than of the vaccines from strains 19 and 82.
Due to very strong general and local inflammatory responses, significantly reducing animal productivity, inactivated vaccine from strain КВ 17/100 KV needs improvements that would allow to reduce its reactogenicity.
Diagnostic means of brucellosis also raise some questions. Today the market offers various diagnostic products therefore raising the question why have so many of them? Each producer claims that its product helps to reveal more responsive animals compared with other diagnostics methods.
At the same time, it is not always possible to diagnose brucellosis in 100% of cases. Quite often the blood of chronic animals doesn’t have specific antibodies that usually are the basis of diagnostics methods. Besides, the disease does not show any signs.
That happens because the agent that persists in macrophages is walled off by cells membranes from any contacts with animal’s immune system. And only occasional weakening of immune resistance (due to the stress, pregnancy, hypothermia, toxicosis, etc.) causing flare up of the disease, might lead to Brucella antigens getting into blood. As a result, long-lived B cells, memory cells that are in the blood, get activated. In a short time they transform into plasma cells that start to produce antibodies.
A blood test made during induction of high titer antibodies can detect that animal is sick. However, conducted during remission the test won’t show antibodies, which makes it impossible to detect the disease.
Agglutination reaction is the most informative to detect brucellosis in early stages or acute phase of the disease. During this period IGM are synthesized in large quantatives.
At later stages (in the chronic course of the disease) IgG, IgA, IgE immunoglobulins are formed and can be detected in CFT.
Besides, recently there have been used allergic tests, ELISA tests; there are being developed new sensitive methods that allow to detect Brucella DNA fragments in blood, tissues or secretions (PCR). This methods are promising but need more time for their proper evaluation.
We offer a fundamentally different approach aimed to detect all infected animals. The method has been developed by Peter E Ignatov, MD and is based on provoking antibody synthesis in chronically infected animals.
The BIV antigen can be used to provoke antibodies synthesis. The antigen is produced at our Bio factory from Brucella abortus strain 19 and contains specific components of nucleoprotein nature with addition of sucrose and gelatin stabilizer. This sterile product does not cause synthesis of brucellar antibodies in healthy animals. It doesn’t induce late-onset hypersensitivity reaction; it is neither reactogenic, nor abortogenic.
If all animals are treated with immunizing dose, the healthy animals will gain a short-term immunity, while sick animals will have provocation of latent brucellosis that would lead to presence of antibodies in the blood.
A diagnostic test for Brucella antibodies performed at a certain time with conventional antigens will allow identifying all infected animals and casting them out for slaughter.
Given that development of acute reaction and formation of antibodies takes time, first diagnostic tests should be conducted 15 days after the treatment. 15 days later a retest should be made to ensure that there are no sick animals.
If positive responses reoccur new tests can be conducted in 15-20 days in order to conduct double result. In complicated cases, when cattle brucellosis is not eliminated in two or three months, we recommended to administer the BIV antigen again. That will help to immunize even more the healthy stock and increase provocative effect in sick animals.
First trials on the cattle were carried in the Danilov District of the Volgograd Region (three farms with two thousand head of cattle participated in the trial).
Before administration of BIV antigen each test showed a positive response in 1,5- 2,0% of the herd. 15 days after its application this figure went up to 4-6%. Retests conducted 15 days after showed another 2-3% of positive responses. In subsequent tests the number of positively responded animals was equal to 0-1%. And after while all farms had only negative results.
In other words a few months of properly organized work will enable to achieve double negative results.

N. Zenov (doctor of veterinary science, Aide to the Production Director of Shchelkovsky Biokombinat)