• Parasites, Hosts and Diseases
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• 제57권2호
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• pp.93-99
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• 2019

Both Plasmodium spp. and Toxoplasma gondii are important apicomplexan parasites, which infect humans worldwide. Genetic analyses have revealed that 33% of amino acid sequences of inner membrane complex from the malaria parasite Plasmodium berghei is similar to that of Toxoplasma gondii. Inner membrane complex is known to be involved in cell invasion and replication. In this study, we investigated the resistance against T. gondii (ME49) infection induced by previously infected P. berghei (ANKA) in mice. Levels of T. gondii-specific IgG, IgG1, IgG2a, and IgG2b antibody responses, $CD4^+$ and $CD8^+$ T cell populations were found higher in the mice infected with P. berghei (ANKA) and challenged with T. gondii (ME49) compared to that in control mice infected with T. gondii alone (ME49). P. berghei (ANKA) + T. gondii (ME49) group showed significantly reduced the number and size of T. gondii (ME49) cysts in the brains of mice, resulting in lower body weight loss compared to ME49 control group. These results indicate that previous exposure to P. berghei (ANKA) induce resistance to subsequent T. gondii (ME49) infection.

• Parasites, Hosts and Diseases
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• 제59권6호
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• pp.565-572
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• 2021

Toxoplasma gondii ME49 infections are typically diagnosed by serological tests. However, serological diagnosis of RH strain-induced toxoplasmosis remains unknown. In order to develop seradiagnosis of above 2 kinds of infections, we generated recombinant virus-like particles (VLPs) displaying the T. gondii rhoptry protein 4 (ROP4) and evaluated their potential in T. gondii ME49 or RH strain infection diagnostics. Mice were orally infected with either the tachyzoites of T. gondii (RH) or cysts of T. gondii (ME49) at various dosages, and sera were collected at regular intervals. ELISA-based serological tests were performed to assess IgG, IgM, and IgA antibody responses against ROP4 VLP antigen and tissue lysate antigen (TLA). Compared to TLA, IgG, IgM, and IgA levels to ROP4 VLP antigen were significantly higher in the sera of T. gondii RH-infected mice 1 and 2 week post-infection (PI). T. gondii-specific IgG antibody was detected at 1, 2, 4, and 8 week PI in the T. gondii ME49-infected mice with infection dose-dependent manner. These results indicated that the ROP4 VLP antigen was highly sensitive antigens detecting T. gondii RH and ME49 antibodies at an early stage.

• Parasites, Hosts and Diseases
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• 제37권3호
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• pp.157-162
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• 1999

Serum from mouse orally ingested with tissue cyst forming stain (Me49) of Toxoplasma gondii was assayed by Western blot and immunofluorescene assay (IFA) to establish early responses in antigenicity of the parasite in mouse model of foodborne toxoplasmosis. Sera were collected weekly to blot the RH antigen transferred onto nitrocellulose paper after being separated by 12% SDS-PAGE. With the second week serum, 34 kDa protein (p34) was detected uniquely, and all antigens of T.gondii were detected with the sera from 3 or 4 weeks. p34 was not a member of the major surface membrane proteins and confirmed to be localized in the rhoptry by IFA. It was secreted into parasitophorous vacuolar membrane (PVM) during the entry into host cells. 10.3% of sera detected p34, while all the ELISA positive sera detected the band. It has diagnostic usefulness of presumed T.gondii infection. We suggest the name of the p34 protein as ROP9.

• Parasites, Hosts and Diseases
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• 제61권4호
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• pp.418-427
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• 2023

Toxoplasma gondii infections are primarily diagnosed by serological assays, whereas molecular and fluorescence-based techniques are garnering attention for their high sensitivity in detecting these infections. Nevertheless, each detection method has its limitations. The toxoplasmosis detection capabilities of most of the currently available methods have not been evaluated under identical experimental conditions. This study aimed to assess the diagnostic potential of enzyme-linked immunosorbent assay (ELISA), real-time polymerase chain reaction (RT-PCR), immunohistochemistry (IHC), and immunofluorescence (IF) in BALB/c mice experimentally infected with various doses of T. gondii ME49. The detection of toxoplasmosis from sera and brain tissues was markedly enhanced in mice subjected to high infection doses (200 and 300 cysts) compared to those subjected to lower doses (10 and 50 cysts) for all the detection methods. Additionally, increased B1 gene expression levels and cyst sizes were observed in the brain tissues of the mice. Importantly, IHC, IF, and ELISA, but not RT-PCR, successfully detected T. gondii infections at the lowest infection dose (10 cysts) in the brain. These findings may prove beneficial while designing experimental methodologies for detecting T. gondii infections in mice.

• Parasites, Hosts and Diseases
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• 제32권1호
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• pp.19-26
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• 1994

Toxoplasma 약독주(ME49 주)의 배양계 확립을 위하여 뇌내 cyst를 마우스 복강에 주입하고 1, 3, 5 그리고 7일후 다시 얻어 배양기 부착성 세포를 배양하는 방법으로 ME49주를 배양하였으며, ME49주의 성장에 미치는 CAMP 및 DHFR억제제의 영향을 관찰하였다. ME49주로 감염된 대식 세포의 형태학적 관찰은 Giemsa 염색방법을 이용하였고 성장정도는 $[^3H]-uracil$ 표지량을 대조군에 대한 비로 나타내었다. 감염 3일 및 5일이 경과된 후에 채취한 복수의 대식세포에서 ME49 주의 bradyzoite가 주로 판찰되었으며, 배양기에서 3일 이상 경과된 후에는 pseudocyst를 형성하기 시작하였고, 5일 10일이 경과되면서 pseudocyst의 크기가 증가하였다. CAMP를 농도별로 처리하였을 때 3일째와 5일째의 복수를 5일간 및 10일간 배양했을 때 농도의존적으로 성장을 촉진하였다. DHFR 억제제중 pyrimethamine의 경우 농도의존적인 성장억제효과를 나타냈고 methotrexate의 경우엔 ME49 주 bradyzoite의 성장에 영향을 미치지 않는 것으로 나타났다. 이상의 결과로 마우스 대식세포내에서 bradyzoite의 배양이 가능하고 그 배양조건은 3일째와 5일째 복수를 5일 이상 10일 정도 배양하는 것이 적당하며 CAMP 및 pyrimethamine이 bradyBoite의 성장을 각각 촉진 및 억제하는 것으로 나타났다.

• Parasites, Hosts and Diseases
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• 제30권2호
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• pp.125-132
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• 1992

Toxoplasma gondii이 약독주인 Beverley주, Fukaya주 띤 MR49주를 각각 감염시킨 BALB/c 마우스에서 발현되는 세포매개 성 및 체액성 면역반응을 비교 관찰할 목적으로 매주 1회씩 10주에 걸쳐 각각 3마리씩 취하여, 소정의 과정을 거쳐 준비한 비장세포에 concanavalin A(Con. A), lipopolysaccharide(LPS) 및 Toxoplasma Iysate를 처리한 후 아세포화 반응의 정도를[3H]-thymidine의 전입량으로 측정, 평가하는 한편, 혈청내 IgG 및 IgM 항체가를 효소결합면역흡착법 (ELISA)으로 측정, 분석하였다. Con. A 및 Toxoplasma Iysate로 처리시 비장세포의 아세포화 반응은 3개주 감염군 모두 대조군에 비해 감염후 1주부터 유의하게 감소되었으나, LPS로 처리시 3개 주 감염군 모두 대조군에 비해 유의한 차이가 없었다 또한 각 주별 감염 마우스 상호간에도 유의 한 차이가 없었다. 혈청내 IgG 항체가는 3개주 감염군 모두 감염후 2주부터 7주까지 계속적으로 증가한 후 그 항체가가 지속되었으며, IgM 항체가는 1주에서 4주 사이에 현저히 높았다. 그러나 카 주별 감염 마우스의 혈청내 IgG 및 IgM 항체가 상호간에는 유의한 차이가 없었다. 이상의 성적으로 보아 T. gondii의 Beverley주, Fukaya주 및 ME49주를 각각 감염시킨 마우스에 있어 감염 초기에는 세포매개성 면역반응이 억제되며, 체액성 면역반응에 있어 IgM 항체는 감염 초기에 증가하였고 IgG 항체는 초기부터 높은 수준으로 장기간 지속됨을 알 수 있었다.

• Parasites, Hosts and Diseases
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• 제56권5호
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• pp.429-435
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• 2018

Toxoplasma gondii is a ubiquitous protozoan parasite responsible for causing toxoplasmosis. Preventive measures for toxoplasmosis are currently lacking and as such, development of novel vaccines are of urgent need. In this study, we generated 2 virus-like particles (VLPs) vaccines expressing T. gondii rhoptry protein 4 (ROP4) or rhoptry protein 18 (ROP18) using influenza matrix protein (M1) as a core protein. Mice were intranasally immunized with VLPs vaccines and after the last immunization, mice were challenged with ME49 cysts. Protective efficacy was assessed and compared by determining serum antibody responses, body weight changes and the reduction of cyst counts in the brain. ROP18 VLPs-immunized mice induced greater levels of IgG and IgA antibody responses than those immunized with ROP4 VLPs. ROP18 VLPs immunization significantly reduced body weight loss and the number of brain cysts in mice compared to ROP4 VLPs post-challenge. These results indicate that T. gondii ROP18 VLPs elicited better protective efficacy than ROP4 VLPs, providing important insight into vaccine design strategy.

• Parasites, Hosts and Diseases
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• 제57권5호
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• pp.543-547
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• 2019

Toxoplasma gondii can infect humans worldwide, causing serious diseases in pregnant women and immunocompromised individuals. T. gondii rhoptry protein 13 (ROP13) is known as one of the key proteins involved in host cell invasion. In this study, we generated virus-like particles (VLPs) vaccine expressing T. gondii rhoptry ROP13 and investigated VLPs vaccine efficacy in mice. Mice immunized with ROP13 VLPs vaccine elicited significantly higher levels of T. gondii-specific IgG, IgG1, IgG2a, and IgA antibody responses following boost immunization and challenge infection, whereas antibody inductions were insignificant upon prime immunization. Differing immunization routes resulted in differing antibody induction, as intranasal immunization (IN) induced greater antibody responses than intramuscular immunization (IM) after boost and challenge infection. IN immunization induced significantly higher levels of IgG and IgA antibody responses from feces, antibody-secreting cells (ASCs), $CD4^+$ T, $CD8^+$ T cells and germinal center B cell responses in the spleen compared to IM immunization. Compared to IM immunization, IN immunization resulted in significantly reduced cyst counts in the brain as well as lesser body weight loss, which contributed to better protection. All of the mice immunized through either route survived, whereas all na?ve control mice perished. These results indicate that the ROP13 VLPs vaccine could be a potential vaccine candidate against T. gondii infection.

• Parasites, Hosts and Diseases
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• 제58권2호
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• pp.185-189
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• 2020

Immunogenicity of dendritic cell-derived exosomes stimulated with Toxoplasma gondii lysates (TLA exo), mixed with cholera toxin as an adjuvant, was investigated in mice immunized via 2 mucosal routes (ocular vs intranasal). BALB/c mice were injected 3 times with TLA exo vaccine at 2 week interval, and the levels of IgG in serum and IgA in tear, saliva, feces, and vaginal wash were measured. To observe the expression of T. gondii-specific B1 gene, mice infected with ME49 T. gondii cysts were immunized with TLA exo or PBS exo (not stimulated with TLA), and their brain tissues were examined. The mice vaccinated via intranasal route elicited significantly higher humoral and mucosal immune responses compared with mice treated with PBS alone. Also, mice immunized via ocular route (by eyedrop) induced significantly higher T. gondii-specific IgG in serum and IgA in tear and feces in comparison with PBS controls. B1 gene expression was significantly lower in TLA exo vaccinated mice than in PBS or PBS exo vaccinated mice. These results demonstrated that ocular immunization of mice with TLA exo vaccine has the potential to stimulate systemic or local antibody responses. This study also highlighted an advantage of an eyedrop vaccine as an alternative for T. gondii intranasal vaccines.

• Parasites, Hosts and Diseases
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• 제53권3호
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• pp.259-263
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• 2015

The increasing prevalence of Toxoplasma gondii infection in the human population in the Republic of Korea (= Korea) is due to various reasons such as an increase in meat consumption. However, the importance of cats in transmitting T. gondii infection through oocysts to humans has seldom been assessed. A total of 300 fecal samples of stray cats captured around Seoul from June to August 2013 were examined for T. gondii B1 gene (indicating the presence of oocysts) using nested-PCR. Fourteen (4.7%) of 300 cats examined were positive for B1 gene. Female cats (7.5%) showed a higher prevalence than male cats (1.4%). Cats younger than 3 months (5.5%) showed a higher prevalence than cats (1.5%) older than 3 months. For laboratory passage of the positive samples, the fecal suspension (0.2 ml) of B1 gene positive cats was orally inoculated into experimental mice. Brain tissues of the mice were obtained after 40 days and examined for the presence of tissue cysts. Two isolates were successfully passaged (designated KNIH-1 and KNIH-2) and were molecularly analyzed using the SAG5D and SAG5E gene sequences. The SAG5D and SAG5E gene sequences showed high homologies with the ME49 strain (less virulent strain). The results indicated the importance of stray cats in transmitting T. gondii to humans in Korea, as revealed by detection of B1 gene in fecal samples. T. gondii isolates from cats were successfully passaged in the laboratory for the first time in Korea.