SPECIES-SPECIFIC POLYMERASE CHAIN-REACTION FOR THE DIFFERENTIATION OFLARVAE FROM DICTYOCAULUS-VIVIPARUS AND DICTYOCAULUS-ECKERTI

Using substantial interspecific differences between the second interna l transcribed spacer (ITS2) region within the rDNA gene of Dictyocaulu s eckerti and Dictyocaulus viviparus a species-specific PCR was develo ped to distinguish between lungworm larvae of the two species from fal low deer and cattle. It was found that the method of DNA extraction wa s crucial for the sensitivity of the PCR. With serial dilutions of DNA extracted from 10000 larvae the ITS2 fragment could be amplified from all dilutions down to a calculated amount of DNA equivalent to one la rva. Using lower numbers of larvae, DNA from at least 100 larvae was n ecessary for a successful amplification. From this extraction a specie s-specific polymerase chain reaction (PCR) product was generated with a calculated amount of DNA equivalent to 33 larvae, whereas amplificat ion of further diluted DNA was not successful. However, in a direct PC R single larvae could be detected after direct PCR amplification witho ut preceding DNA extraction.