• 대한수의학회지
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• 제37권4호
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• pp.785-791
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• 1997

Theileria spp.의 생활환에 대해서는 여러종류의 책을 통해서 잘 소개되어 있다. 그중 Theileria spp.의 분열소체 즉, merozoite는 주로 숙주의 적혈구내에 존재하는데 진드기에 의해 흡혈되지 않으면 더이상 발육하지 못하고 생을 마감한다고 여겨 왔다. 그러나 적혈구내 merozoite가 임파구에 다시 들어가 schizont로 복귀하여 분열 증식된다는 가설은 아직까지 증명된 바 없다. 본 실험은 T sergenti merozoite의 schizont로의 복귀를 입증하고자 수행되었다. T sergenti에 감염되지 않은 3개월령의 송아지를 비장적출시킨 후 T sergenti merozoite에 감염된 순수적혈구를 인공감염시켰다. 인공감염후 경시적으로 혈액과 임파액을 채취하여 적혈구내 T sergenti 감염을 조사하고 백혈구 감별혈구를 계산하였으며 임파구내 schizont 출현을 관찰하여 다음과 같은 결과를 얻었다. 1. 혈구내원충 감염율(parasitemia : PE)은 인공감염후 28일째 최고치인 10.5%를 보였으며 그후 5%이내의 수준을 유지하다가 70일째 다시 8.5%의 상승점을 보였다. 2. 백혈구 감별혈구계산에서는 감염초기에는 호중구가 주종을 이루다가 감염후 19일을 기점으로 임파구(60~80%)가 급격히 증가하여 실험종료 때까지 유지되었다. 3. 인공감염후 19~23일, 59~63일 사이에 말초혈액내 임파구에서 분열 증식하고 있는 schizont를 관찰할 수 있었다. 4. 인공감염후 7일부터 림프액내 임파구의 크기가 커지면서 blast-formation이 진행되었으며 실험종료때까지 유지되었다. 이상의 결과로 보아 적혈구내 merozoite가 임파구에 다시 들어가 schizont로 복귀하여 분열 증식함을 입증하여 기존의 T sergenti 생활사는 수정되어야 된다고 사료된다.

• 대한수의학회지
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• 제37권1호
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• pp.189-194
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• 1997

The life cycle of Theileria sergenti(T sergenti) in cattle, especially Korean native cattle, was not proved clearly. To find schizont stage in the life cycle of T sergenti in Korean cattle, T sergenti schizonts in the cells of parotid lymph nodes from 10 adult Korean cattle were examined. Lymphoid cells which were separated from these lymph nodes were cytocentrifuged to observe the parasites in the cells. T sergenti schizonts were detected in the cells of lymph nodes of 6 cattle out of them by IFA(Indirect Fluorescent Antibody) test and Giemsa stain. By peroxidase stain, the cells which contain schizonts were proved lymphoid cells. T sergenti schizonts identified by IFA test were able to be restained by Giemsa stain. Also, merozoites were observed in peripheral blood of the same 6 cattle that had schizonts, by giemsa stain, but not observed in the 4 cattle that had not been detected schizonts. As a part of life cycle of T sergenti, schizonts were observed in the lymphoid cells of Korean cattle.

• 한국동물위생학회지
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• 제13권2호
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• pp.189-195
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• 1990

During 9 months (March-November, 1989), observation of Leucocytozoon infection rate to blood and parenchymatous viscera (spleen, liver, heart) in Pusan, Gyeongnam (Kimhae, Yangsan) districts slaughtered chicken and the results obtained were as follow : 1. Among the blood smear sample of 213 heads of the chicken, 43 heads (20.2%) were infected with Leucocytozoon 2nd stage gametocyte and 4 heads (1.9%) were mixed infected with Leucocytozoon 5th stage gametocyte. 2. In histopathological detection of schizont in tissues section of spleen, liver and heart, there were 16.7% in spleen, 5.6％ in liver and 9.1％ in heart, mean detection rate were 10.6%. Spleen had the highest detection rate of schizont. 3. In seasonal-related Infection rate, summer was higher than spring.

• Parasites, Hosts and Diseases
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• 제48권4호
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• pp.319-324
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• 2010

A family of calcium-dependent protein kinases (CDPKs) is a unique enzyme which plays crucial roles in intracellular calcium signaling in plants, algae, and protozoa. CDPKs of malaria parasites are known to be key regulators for stage-specific cellular responses to calcium, a widespread secondary messenger that controls the progression of the parasite. In our study, we identified a gene encoding Plasmodium vivax CDPK4 (PvCDPK4) and characterized its molecular property and cellular localization. PvCDPK4 was a typical CDPK which had well-conserved N-terminal kinase domain and C-terminal calmodulin-like structure with 4-EF hand motifs for calcium-binding. The recombinant protein of EF hand domain of PvCDPK4 was expressed in Echerichia coli and a 34 kDa product was obtained. Immunofluorescence assay by confocal laser microscopy revealed that the protein was expressed at the mature schizont of P. vivax. The expression of PvCDPK4-EF in schizont suggests that it may participate in the proliferation or egress process in the life cycle of this parasite.

• 대한수의학회지
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• 제34권1호
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• pp.135-139
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• 1994

1992-1993년 호남지방의 4개 양계장에서 처음으로 닭의 Leucocytozoon caulleryi 자연감염증을 보이는 87수를 검색하였는데, 임상증세와 혈액내 merozoite 및 gametocyte 검출 그리고 내장기관으로부터 schizont의 발견으로 본 질병을 확증할 수 있었다. 본 감염증은 일년 중 6월 하순부터 9월 중순까지에 발견되었으며, 자연감염된 혈액(merozoite포함)을 미감염된 닭에 접종하여 인공감염상을 볼 수 있었다. 자연감염후 회복된 닭중 1수는 12월에 간에서, 또 다른 1수는 다음해 2월에 심장 근육에서 schizont가 발견되어 본 감염증의 재발이나 동절기를 지나는 장기간 감염 가능성을 보여 주었다. 본 원충의 gametocyte 추출물에서 특이 항원 항체 반응을 보이는 polypeptide는 50.1kD이었다.

• Parasites, Hosts and Diseases
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• 제22권2호
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• pp.267-272
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• 1984

1983년 6월에 일본으로부터 자연농권 동물권에 수입된 3세령의 반umboldt젠귄 4수가 입사한지 일주만에 갑자기 식욕절폐, 원기소침하여 4∼6일만에 3수가 폐 사하였다. 환조의 혈액도말표본에서 성숙적혈구내에 발육단계가 다른 기생체가 확인되었다. 폐사한 동물은 폐장과 심장에서 심한 수종성 변화가 인정되었고 간장과 비장이 종창해 있었다. 각 장기의 조직학적 결사에서 간회, 등장 및 폐장등에서 광범위하게 현저한 세강훈 피계세계의 증식과 활성화가 관찰되었고 이들 세포에서 여러 발육단계의 schizont가 확인되었다. 이상의 관찰보고는 국내에서 조류의 말라리아 유행을 처음으로 기록한 것이다.

• 한국잠사곤충학회지
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• 제27권1호
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• pp.1-11
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• 1985

1979년 경북지방에서 발생한 병잠으로부터 분리된 새로운 미포자충 K79의 형태, 성장, 발육경과 및 분류학적 위치를 구명하기 위하여 포자의 병원성, 광학현미경에 의한 감염조직의 소견, 전자현미경적 소견을 조사한 결과는 다음과 같다. K79포자의 병원성은 N. bombycis 보다 약하였고 누에에 대한 K79의 감염부위는 중양피막세포, 혈구, 기관피막, 지방조직, 견사선이었다. K79의 발육과정은 sporoplasm, schizont, sporont, sporoblast, spore의 단계로서 N. bombycis와 유사하였으나 발육속도는 늦었다. 미포자충 포자의 전자현미경적인 미세구조는 포자외각의 돌출부와 돌출부사이가 44.28mm였다. 또한 anchoring disk는 우산형이었고 polaroplast, lamellae는 manubroid 상단부에 부착되어 있었다. 극사의 coil 전회수는 K79 16회이고 coil 각도는 75$^{\circ}$였고, 핵은 두 개의 연핵으로 되어 있어 분류학적으로 보면 Nosema 속에 속하는 신종의 미포자충이라고 사료되며 그 표기는 Nosema sp. K79로 기록함이 타당하다고 본다.

• Parasites, Hosts and Diseases
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• 제53권1호
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• pp.43-49
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• 2015

The aim of the study was to explore the possible molecular markers of chloroquine resistance in Plasmodium vivax isolates in Thailand. A total of 30 P. vivax isolates were collected from a malaria endemic area along the Thai-Myanmar border in Mae Sot district of Thailand. Dried blood spot samples were collected for analysis of Pvmdr1 and Pvcrt-o polymorphisms. Blood samples ($100{\mu}l$) were collected by finger-prick for in vitro chloroquine susceptibility testing by schizont maturation inhibition assay. Based on the cut-off $IC_{50}$ of 100 nM, 19 (63.3%) isolates were classified as chloroquine resistant P. vivax isolates. Seven non-synonymous mutations and 2 synonymous were identified in Pvmdr1 gene. Y976F and F1076L mutations were detected in 7 (23.3%) and 16 isolates (53.3%), respectively. Analysis of Pvcrt-o gene revealed that all isolates were wild-type. Our results suggest that chloroquine resistance gene is now spreading in this area. Monitoring of chloroquine resistant molecular markers provide a useful tool for future control of P. vivax malaria.

• Parasites, Hosts and Diseases
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• 제60권6호
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• pp.401-407
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• 2022

Antimalarial drugs play an important role in the control and treatment of malaria, a deadly disease caused by the protozoan parasite Plasmodium spp. The development of novel antimalarial agents effective against drug-resistant malarial parasites is urgently needed. The novel derivatives, SKM13-MeO and SKM13-F, were designed based on an SKM13 template by replacing the phenyl group with electron-donating (-OMe) or electron-withdrawing groups (-F), respectively, to reverse the electron density. A colorimetric assay was used to quantify cytotoxicity, and in vitro inhibition assays were performed on 3 different blood stages (ring, trophozoite, and schizonts) of P. falciparum 3D7 and the ring/mixed stage of D6 strain after synchronization. The in vitro cytotoxicity analysis showed that 2 new SKM13 derivatives reduced the cytotoxicity of the SKM13 template. SKM13 maintained the IC₅₀ at the ring and trophozoite stages but not at the schizont stage. The IC₅₀ values for both the trophozoite stage of P. falciparum 3D7 and ring/mixed stages of D6 demonstrated that 2 SKM13 derivatives had decreased antimalarial efficacy, particularly for the SKM13-F derivative. SKM13 may be comparably effective in ring and trophozoite, and electron-donating groups (-OMe) may be better maintain the antimalarial activity than electron-withdrawing groups (-F) in SKM13 modification.

• Parasites, Hosts and Diseases
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• 제54권4호
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• pp.385-391
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• 2016

The discovery and understanding of antigenic proteins are essential for development of a vaccine against malaria. In Plasmodium falciparum, Pf92 have been characterized as a merozoite surface protein, and this protein is expressed at the late schizont stage, but no study of Pv92, the orthologue of Pf92 in P. vivax, has been reported. Thus, the protein structure of Pv92 was analyzed, and the gene sequence was aligned with that of other Plasmodium spp. using bioinformatics tools. The recombinant Pv92 protein was expressed and purified using bacterial expression system and used for immunization of mice to gain the polyclonal antibody and for evaluation of antigenicity by protein array. Also, the antibody against Pv92 was used for subcellular analysis by immunofluorescence assay. The Pv92 protein has a signal peptide and a sexual stage s48/45 domain, and the cysteine residues at the N-terminal of Pv92 were completely conserved. The N-terminal of Pv92 was successfully expressed as soluble form using a bacterial expression system. The antibody raised against Pv92 recognized the parasites and completely merged with PvMSP1-19, indicating that Pv92 was localized on the merozoite surface. Evaluation of the human humoral immune response to Pv92 indicated moderate antigenicity, with 65% sensitivity and 95% specificity by protein array. Taken together, the merozoite surface localization and antigenicity of Pv92 implicate that it might be involved in attachment and invasion of a merozoite to a new host cell or immune evasion during invasion process.