hi you can check your all reagents and the things used in your experiment should not be polluted. if everything is ok, and still you are getting false positive results then you have to change the place for your experiment.

First, I think you can check the specificity of your primers by doing PCR method using F3 and B3 as primers. If PCR product show all lane (Xv, Xe, Ps, Ea), it's mean that your primer have non-specific to the other DNA.

PS. Don't remember that LAMP method is very easy to contaminated than PCR method. 

Thak you for your answer and advice.

Firstly I have done PCR with F3 and B3 primers. It was specifity to only Xv, which I wanted :)

Next I have done reaction:

20 ul reaction with 2 ul 10x Isothermal Buffer (Optigene), 5mM MgSO4,5M Betaine, 1.4 mM dNTP mix , 1,6 uM of each FIP and BIP, 1,6 uM of each F3 and B3, and 8U GspSSD2.0 Polymerase (Optigene), 3,2 ul template DNA, and molecular grade water.

1 hour 65°C

results:

M(100bp), negative control, Xv, Xv, Xe, Xv, Ea, Ps, Cms, Xg

I see diferent in this sampes. Do you think that will be look on Real-time LAMP? May I change concetration Mg? Do I decrease temperature?

Thanks for your advice

Dagmar

First, I think it's good result for negative control. The Xv products are really good, but your problem is the false positive to other DNA, right? So, my comment is may be you can decreased the incubation time to be 30- 40 min because from you picture it's seem like the Xv product is very strong while the others are weak or low concentrations (except Ea and Cms). or may be you can increase temp. to be 66-67 C. 

PS. I have question about the concentration of the outer and inner primers in the reaction why you use the same concentrations (1.6 uM) or it is your mistake of typing information. Because normally the inner primers should be more than outer primers 8-10 fold. Good luck for you.