In our study on Mithun (Bos frontalis) we found that Mycobacterium tuberculosis complex specific serum PCR detected more animals positive for the infection those could not be detected with intradermal tuberculin test. However, by no means, we were able to confirm that the animals detected positive with PCR were really infected with tuberculosis. How can the test be authenticated?
Article Detection of Mycobacterium tuberculosis complex infection in...
Sir though I am a plant virologist I would like to answer based on my experiences (good and bad)
1. Mycobacterium tuberculosis complex specific serum PCR detected more animals positive
Such results are based on polyclonal antibodies which may not be affinity purified, moreover the bacterial coat is composed of many polypeptides and Sugar. I would suggest use of antibodies raised against one specific protein of Mycobacterium tuberculosis, from bacterial over expressed protein.
2. few animals detected positive with PCR
I faced such a situation, the results may be due to inhibitors of Taq. so diluting the sample may work (as dilution reduces the inhibitors, but PCR can detect 1 (in my experience 100) pathogen.
The specimen may not have Mycobacterium tuberculosis, The PCR product needs to be cloned and sequenced (atleast 500bp). If not what is being amplified.
Disease symptoms may not be corelatable with pathogen number, The clinical signs may come a long time after infection. There is a mismatch always between pathogen load and symptoms in certain diseases.
I requested the reason for No, from Azhar Chafat and Hadeel Albayati ·
Sir, Mycobacterium tuberculosis complex produce granulomatous inflammation in lungs or any other body organ depending upon the exposer to bacterium. It is less likely to come in circulation. And if comes, then it depends on chance factor that we get bacterium in blood sample. and chances also further decreases for serum.
In above study, its looking bright spot that serum based early diagnosis may be done for tuberculosis. We must track these three serum PCR based positive animals for signs and disease progression, that will be better to authenticate the methodology of early diagnosis of TB.
I agree with Mukesh Thakur that bacteria in blood or serum is highly unlikely in tuberculosis
Dear you have very little chance in getting tuberculosis circulating in serum.
Dear friends, you all had a concern that bacteria do not come in circulation that is why serum is not good for preparation of the templet. However, the concept of serum PCR is that whenever there is infection bacteria are killed and degraded by macrophages and other immune effectors leading to release of DNA in circulation and that bacterial DNA is usually the target of Serum PCR. That is why I think that serum PCR should be compared to known positive and negative cases of tuberculosis.
- Badges
- Science method