After our interesting experiments we were of course really curious about the results.
In total we had 43 bee samples, but we decided to include just 34 in our first investigations.
In order to be able to compare all the signals and to correctly interpret the results we included a positive control (obtained from Prof. Nowotny from the veterinary university of Vienna) as well as a negative control on each gel.
Important for the correct interpretation of the gel is not the intensity of the signals but the distance the DNA (stained with SYBR green) migrated in the electric field from the starting slots. The size of the DNA fragments can be estimated by the use of a DNA size marker which is also run on the same gel.
All this knowledge allowed us to analyze and interpret the DNA gels under UV-light.
As can be seen on figure 1 there are no fluorescent signals at positions 23, 31 and 35. These samples therefore are not infected with APV.
Sample 35 and 36 are treated in a special way: before the RNA isolation procedure, we separated all the varroa mites from the bees. Sample 35 contains the “purified” bees, sample 36 just the mites.
32 bee samples (all carrying varroa mites) out of 34 were infected with the APV virus, corresponding to an infection rate of about 94%.
This allows us to draw an interesting conclusion. Just bees attacked by mites were also infected with the virus. Sample number 35 where the mites were removed, was clean. But the mites taken from this bee sample were infected by the virus!
This fascinating finding supports reports in the literature saying that the infection of the bees with the virus is transferred by the mites. This result totally enhances our working hypothesis and confirms previous scientific investigations.
Additionally, it shows that the bees are not always infected with the virus when the immune system is intact.
The second figure shows that the virus DWV is also very common in the local bee population. No signal can be detected in the lanes 18, 24 and 25 meaning that 33 samples out of 36 are positive. This makes an infection rate of about 91%.
The most interesting and also important part of our project is the detection of the IAPV shown in figure 3 and 4. We tested 32 bee samples, 31 of which were obviously negative, meaning not infected with IAPV.
Sample 32 showed a very weak positive signal which could not clearly be identified. The whole team became very nervous. Did we identify the dangerous IAPV? But: why is the signal that weak? Was it a mistake during the analysis?
To avoid misinterpretation we immediately started a control experiment.
The result was clearly negative. The explanation quite obvious: during the experiment tiny liquid particles of the positive control, so-called aerosols,
contaminated sample 32 and falsified the result.
In order to avoid these contaminations we decided to strictly separate the handling of the positive controls and the samples during the preparation of the PCR reactions. We repeated the whole experiment again and the result was very calming: our bee samples were 100% negative, none of them was infected with IAPV.
Nevertheless, this result does not mean that IAPV is not yet present in the Austrian bee population since we analyzed just a very small portion.
Most probably it is just a question of time till the virus is present in Austria. In Portugal and in other European countries there are already reports about Colony Collapse Disorder (CCD).