domingo, 18 de octubre de 2009

Reverse Transcription-PCR in biopsy specimens from leprosy cases

From: Clapasson A., Genoa, Italy

Dear Dr Haroen, Thank you very much for your message (LML Oct. 16th 2009). I read it with interest. Your questions are reported in “black”.

“Is it because I used different primer that might cause the positive result from my research is very low (56,7%)?” LP1 and LP2 are good primers for first step in research of RLEP and you find these repetitive sequence thirty-nine times. These primers have got interesting characteristics, but if your BAR is viable, its rRNA 16s is amplified more than thirty-nine times. Kurabachew uses primers for rRNA 16s.

“Or is there any other explanation that can cause this?” Yes there is, are you sure about your extraction? This step is more important than PCR.

“Is this mean that M. leprae was viable on the skin surface?”I ask you: what is the morphological index (MI) in the skin smears? What is the aspect of your BARs in the nasal swab? If there were “solids” we may assume they were viable.

“Is there any possibility that M. leprae from skin structure can come out to the surface of the skin lesion?” The main portals of exit are the upper airways and ulcerated or abraded skin lesions. Is there any possibility that M. leprae can live outside the body (enviroment: water, soil, etc)?It may survive with the right conditions of humidity up to 40 days.

“So what is the meaning of M. leprae is an obligate intracellular?” Interesting question. I can tell you that it is a dogma; but I doubt when I see the big hyper-chromic globes in the nasal smears of untreated LL patients, that this dogma is always true (I suspect it is not!).

“But from 1 specimen that positive RNA from skin swab, the RNA biopsy was negative. Is that means that M. leprae that viable on the skin surface came from environment? Or is there any other explanation regarding this result?” A very interesting paper is that of Dr Williams. She says that if there are a lot of T cells, these can inhibit your PCR. M. leprae does not live on the skin but into the skin.

My best regards, Andrea

PS.I apologize if I was imprecise but, in some points I have expressed my opinion.

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