• Parasites, Hosts and Diseases
• /
• 제44권3호
• /
• pp.187-196
• /
• 2006

The mammalian trematode Paragonimus westermani is a typical digenetic parasite, which can cause paragonimiasis in humans. Host tissues and blood cells are important sources of nutrients for development, growth and reproduction of P. westermani. In this study, a cDNA clone encoding a 47 kDa hemoglobinase of P. westermani was characterized by sequencing analysis, and its localization was investigated immunohistochemically. The phylogenetic tree prepared based on the hemoglobinase gene showed high homology with hemoglobinases of Fasciola hepatica and Schistosoma spp. Moreover, recombinant P. westermani hemoglobinase degradaded human hemoglobin at acidic pH (from 3.0 to 5.5) and its activity was almost completely inhibited by E-64, a cysteine proteinase inhibitor. Immunohistochemical studies showed that P. westermani hemoglobinase was localized in the epithelium of the adult worm intestine implying that the protein has a specific function. These observations suggest that hemoglobinase may act as a digestive enzyme for acquisition of nutrients from host hemoglobin. Further investigations may provide insights into hemoglobin catabolism in P. westermani.

• Parasites, Hosts and Diseases
• /
• 제41권1호
• /
• pp.47-55
• /
• 2003

We compared patterns of intraspecific polymorphism of two markers with contrasting modes of evolution, nuclear ribosomal DNA (rDNA) and mitochondrial DNA (mtDNA), in the lung fluke, diploid and triploid Paragonimus westermani from three geographical regions of Korea. The genetic distances between three populations of Korean diploid and triploid P. westermani showed no significant difference in the nucleotide sequences of the mitochondrial cytochrome c oxidase subunit 1 (mtCOI) and ribosomaal second internal transcribed spacer (ITS2) genes. A highly resolved strict-consensus tree was obtained that illustrated phylogenetically useful information of the ITS2 and mtCOI sequences from diploid and triploid P. westermani.

• Parasites, Hosts and Diseases
• /
• 제37권1호
• /
• pp.55-57
• /
• 1999

During the period from October 1996 to November 1998, the infection status of Paragonimus westermani metacercariae in freshwater crayfish (Cambaroides similis) collected from Bogildo (islet), Wando-gun, Chollanam-do, which is known for an endemic area of P. westermani in Korea, were examined. The average infection rate of Paragonimus metacercariae in crayfish was 88.6%, and mean number of metacercariae per infected crayfish was 30.2. This metacercarial density was the highest in the group of weight in 7.1-9.0 g. These results suggest that the natural life cycle of P. westermani is still well-preserved in Bogildo.

• Parasites, Hosts and Diseases
• /
• 제51권6호
• /
• pp.621-627
• /
• 2013

Paragonimiasis is a food-borne parasitic zoonosis caused by infection with lung flukes of the genus Paragonimus. In Vietnam, research on Paragonimus and paragonimiasis has been conducted in northern and central regions of the country. Using a combination of morphological and molecular methods, 7 Paragonimus species, namely P. heterotremus, P. westermani, P. skrjabini, P. vietnamensis, P. proliferus, P. bangkokenis, and P. harinasutai, have been identified in Vietnam. Of these, the first 3, P. heterotremus, P. westermani, and P. skrjabini, are known to infect humans in other countries. However, in Vietnam, only P. heterotremus, found in some northern provinces, has been shown to infect humans. Even nowadays, local people in some northern provinces, such as Lai Chau and Yen Bai, are still suffering from P. heterotremus infection. In some provinces of central Vietnam, the prevalence and infection intensity of P. westermani metacercariae in freshwater crabs (the second intermediate hosts) are extremely high, but human cases have not been reported. Likewise, although P. skrjabini was found in Thanh Hoa Province, its pathogenicity to humans in Vietnam still remains uncertain. The results of molecular phylogenetic analyses of Vietnamese Paragonimus species provides new insights on the phylogeny and taxonomy of the genus Paragonimus. Comprehensive molecular epidemiological and geobiological studies on the genus in Vietnam and adjacent countries are needed to clarify the biodiversity and public health significance of the lung flukes.

• Parasites, Hosts and Diseases
• /
• 제30권1호
• /
• pp.43-48
• /
• 1992

폐흡충(Paragonimus westermani) 피낭유충을 마우스에 감염시킨 후 in vitro상에서 비장 림프구에 폐흡충 항원, phytohemagglutinin(PHA) 및 혈청 첨가시 림프구 아세포화 반응을 관찰하였다. PHA로 자극시킨 감염 마우스의 비장 림프구는 비감염군에 비해 감염 1 주 후에 평균 53.6%의 유의한 증식 억제를 관찰하였고, 폐흡충 성충항원으로 자극시킨 경우 감염 마우스의 비장 림프구의 증식은 감염 1 주 후부터 6 주까지 비감염군에 비해 중가되었으며 특히 감염 1 주와 4 주 후에는 각각 평균 200.9% 및 280.2%의 유의한 수준으로 증가되었다. 또한 피낭유충 항원으로 감염 마우스의 비장 림프구를 자극시에도 비감염군의 림프구의 증식에 비해 전반적으로 증가되었으며 특히 감염 4 주 째에는 평균 180.5%의 유의한 수준으로 증가하였다. 폐홉충에 감염된 마우스의 감염 4 주 째 혈청을 PHA로 자극시킨 비감염 마우스 비장 림프구에 첨가하였을 때 유의한 수준의 증식의 억제를 관찰하였다. 이러한 결과들로 보아 폐흡충 감염 마우스에서 림프구가 세포 매개성 면역에 관여하며 감염 혈청이 PHA에 대한 T 림프구의 증식을 억제함을 알 수 있었다.

• Parasites, Hosts and Diseases
• /
• 제37권4호
• /
• pp.285-287
• /
• 1999

Changes in the expression level of splenocyte $IFN-{\gamma}$mRNA of Sprague-Dawley (SD) rats infected with Paragonimus westermani were analyzed by competitive reverse transcription-polymerase chain reaction (RT-PCR) followed by southern blot. The template RNA was extracted from the splenocytes of rats infected with 20 metacercariae of P. westermani. The products of competitive RT-PCR were subjected to southern blot and enhanced chemiluminescence (ECL), and analyzed with a densitometer. In comparison with that of uninfected control rat splenocytes (value of 1), the levels of mRNA expression of $IFN-{\gamma}$had changed to 0.747 at 1 week post infection (PI), 0.00175 at 2 week PI, 0.0217 at 3 week PI, 0.194 at 4 week PI and then to 0.537 at 5 week PI. The level at 7 week PI had returned to 1.25, comparable with that of uninfected rats. These results show that, when infected with p. westermani, the levels of $IFN-{\gamma}$ mRNA of SD rat splenocytes were remarkably reduced by more than 500 times at 2 week PI and restored to normal level at 7 week PI.

• Parasites, Hosts and Diseases
• /
• 제47권4호
• /
• pp.425-426
• /
• 2009

The present study investigated the infection status of Paragonimus westermani metacercariae in freshwater crabs (n = 363) and crayfish (n = 31) from October 2007 to October 2008 using the crush method. All of the freshwater crabs, Eriocheir japonicus, were negative for P. westermani metacercariae while 10 (32.3%) of the 31 examined crayfish were positive. The 10 positive crayfish were caught in Haenam, Jeollanam-do, and there were 8-59 (mean 28.4) metacrcariae per infected crayfish. These results suggest that P. westermani metacerariae are still transmitted by crayfish enzootically in southern Korea, and that freshwater crabs may transmit metacercariae only on rare occasions.

• Parasites, Hosts and Diseases
• /
• 제29권4호
• /
• pp.397-402
• /
• 1991

폐츱충(Paragonimus westermani) 감염시 탈낭유충은 숙주내 여러조직을 거친 후 폐에 기생하게 되는데 이때 조직반응과 더불어 혈액내 호산구와 IgE 항체가의 변등이 일어난다. 이 실험에서는 백서에 폐흡충을 감염시키고 혈청내 총 IgE와 특이 IgG 항체값을 시간 경과별로 측정하여 감염후 혈청내 항체가의 변증을 관찰하였다. 폐흡충 퍼낭유충 20개를 백서에 경구 감염시키고 시기별(0,1,2,3,4,0,8주)로 IgE의 변동을 avidin-biotin을 이용하여 효소표식 면역검사법 (enzyme-linked immunosorbent assay: ELISA)으로 측정하였으며 IgG는 통상적인 ELISA 방법을 이용하여 측정하였다. 실험군의 혈청내 총 IgE치는 감염 3주와 3주 후에 흡광도가 각각 0.18±0.042, 0.18±0.081이었으나, 4주에 0.28±0.151로 급격히 중가하었으며 8주까지 지속적인 상승(0,43±0,055)을 보였다. 반면 대조군의 경우 전 실험기간을 통해 0.07∼0.12로 낮은 항체가가 유지되었다. 또한 실험군의 혈청내 IgG 항체는 감염 3주 후에 흡광토 0.20±0,032로 증가하기 시작하여 8주에 0.31±0.067을 보였으나 대조군에 비해 크게 증가되지 않았다. 이상의 결과로 보아 비호적숙주인 백서에서 폐흡충의 감염이 IgE 및 IgG 항체를 증가시킴을 알 수 있었다.

• Parasites, Hosts and Diseases
• /
• 제29권1호
• /
• pp.43-54
• /
• 1991

폐홉충(Paragonimus westermani) 초기 감염시의 숙주 면역 기전을 알아보기 위하여 폐흡충 피낭유충을 백서에 감염시켜 주별(주별)로 항혈청을 분리하고 등일 백서에서 복강 대식세포(homologous rat peritoneal macrophage)를 얻은 다음, 이들과 폐흡충 탈낭유충 및 숙주 조직 이행중인 유약충으로 effector system을 조작하여 폐흡충 유충에 대한 항체 의존성 대식세포 공격기전을 관찰하였다. 백서 복강 대식세포는 항혈청 출현 시에만 폐흡충 탈낭유충에 대한 세포부착 반응(cell adherence reaction)을 보였고 이 반응에는 보체가 관여하지 않았다. 폐흡충 감염 1주에서 8주까지의 백서 항혈청 중 2주째에 분리한 항쳔청 실험군에서 100%의 세포부착 반응을 나타내었고 사멸된 충체를 관찰할 수 있었으며, 세포부착 반응은 탈낭 유충기에서만 나타나는 반면 조직이행 유약충에서는 전혀 그 반응을 인정할 수 얼어 폐흡충 감염에 따른 항체의존성 숙주 세포 매개독성(antibodydependent cell·mediated cytotoxicity)은 발육단계 별 특이성을 보였다. 한편, 대식세포의 공격에 의하여 사멸된 폐흡충 탈낭유충의 형태학적 특징은 대식세포와 유충 사이에 형성되는 fuzzy material, tegumental syncytium 내의 미세구조의 변성 및 syncytium과 근육층을 연결하는 tubular tunnel의 형성 등이었다.

• Parasites, Hosts and Diseases
• /
• 제40권2호
• /
• pp.89-92
• /
• 2002

The cysteine proteases of Paragonimus westermani metacercariae are involved in metacercarial excystment, host immune modulation, and possibly in tissue penetration. In order to clarify the origin of the enzymes, 28 and 27 kDa cysteine proteases in metacercarial excretory-secretory products were purified through the FPLC system using Mono Q column chromatography. The polyclonal antibodies to the enzymes were produced in BALB/c mice. Immunolocalization studies revealed that both cysteine proteases were distributed at the linings of excretory bladder and excretory concretions of the metacercariae. It was suggested that the excretory epithelium of P. westermani undertake the secretory function of metacercarial cysteine proteases, in addition to its role as a route for eliminating waste products.