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유통식육에서의 톡소포자충 검출을 위한 유전자검사법 개발

Real-time PCR assay for the Detection of Toxoplasma gondii in Retail Meats: Proof-of-concept Study

  • 윤한성 (식품의약품안전처 미생물과) ;
  • 서수환 (식품의약품안전처 미생물과) ;
  • 곽효선 (식품의약품안전처 미생물과) ;
  • 주인선 (식품의약품안전처 미생물과)
  • Yun, Han Seong (Food Microbiology Division, Ministry of Food and Drug Safety) ;
  • Suh, Soo Hwan (Food Microbiology Division, Ministry of Food and Drug Safety) ;
  • Kwak, Hyo-Sun (Food Microbiology Division, Ministry of Food and Drug Safety) ;
  • Joo, In-Sun (Food Microbiology Division, Ministry of Food and Drug Safety)
  • 투고 : 2017.02.20
  • 심사 : 2017.04.24
  • 발행 : 2017.06.30

초록

인수공통 감염증의 하나인 톡소포자충의 검출을 위해서는 대부분은 ELISA 법이 사용 되고 있으나, 충체가 사멸된 후에도 양성반응이 나타나는 등 사용에 제한이 있다. 반면 유전자 검출법은 현재 감염상태를 확인 할 수 있기 때문에 식중독 원인조사 등에 적합하다고 판단되어 이를 활용하여 본 연구를 진행하였다. 톡소포자충의 유전정보를 통해 529 repeat region의 염기서열을 얻고, 프라이머 및 TaqMan 프로브를 설계하여 real-time PCR을 이용한 검출법을 개발하였다. 검출한계(lower limit of detection) 및 적정곡선을 확인한 결과 10 genomic DNA copy가 검출한계로 확인되었고, 정량을 위한 곡선은 $10^1{\sim}10^6$ DNA copies까지 0.999의 $R^2$ 값을 나타내었다. 개발된 검출법의 증폭효율을 비교하기 위해 B1 gene 타겟 프라이머 세트와 타입별 검출한계를 비교한 결과, type 1, 2, 3 톡소포자충에서 같거나 더 나은 검출한계를 보였다. 또한 식품에서 주로 분리되는 식중독 세균 14종 및 원충 3종에 대해 특이도를 비교한 결과, 모두 음성으로 나타났다. 개발된 검출법을 식육검체에 적용하였을 때 type 1, 2, 3에서 모두 원활한 검출결과를 보여 증폭방해물질이 존재하지 않은 것으로 확인되었다. 본 연구를 통해 개발된 유전자검출법은 국내 유통 중인 식육에서 인수 공통감염 원충의 하나인 톡소포자충의 감염 여부를 확인하는 사전적 모니터링의 방법으로 활용될 예정이다.

Although many PCR-based assays have been developed, the majority of rapid detection of Toxoplasma gondii in animal and their meat product has been dependent on immunogenic assays. Thus, there is still a need for more reliable PCR based detection method for T. gondii in retail meats. Recently, a 529-bp repeat element that exists in 200-300 copies per genome of T. gondii genome had been spotlighted for its usefulness as potential detection targers. In this study, the 529-bp repeat element was selected for real-time PCR to detect three types of T. gondii (type I, II and III). A primer pair targeting 82-bp of the 529-bp element detected all three types of T. gondii and showed high level of specificity against 14 different food-borne pathogens as well as 3 protozoan parasites such as Giardia lamblia, Cryptosporidium parvum and Entamoeba histolytica. Application of the new real-time PCR assay in meat samples showed improved detection sensitivity compared to the B1-gene targeted method suggesting potential new target for Toxoplasma gondii screening in retail meats.

키워드

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