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H Nagasawa

Publications and source records attributed to H Nagasawa.

At least 19 recordsLinked to original sources
PubMed2006

The usefulness of a continuous administration of tirapazamine combined with reduced dose-rate irradiation using {gamma}-rays or reactor thermal neutrons.

We clarified the usefulness of the continuous administration of tirapazamine (TPZ) in combination with reduced dose-rate irradiation (RDRI) using gamma-rays or reactor thermal neutrons. Squamous cell carcinoma (SCC) VII tumour-bearing mice received a continuous administration of 5-bromo-2'-deoxyuridine (BrdU) to label all proliferating (P) cells. Then, they received a single intraperitoneal injection or 24 h continuous subcutaneous infusion of TPZ in combination with conventional dose-rate irradiation (CDRI) or RDRI using gamma-rays or thermal neutrons. After irradiation, the tumour cells were isolated and incubated with a cytokinesis blocker, and the micronucleus (MN) frequency in cells without BrdU labelling ( = quiescent (Q) cells) was determined using immunofluorescence staining for BrdU. The MN frequency in the total tumour cells was determined using tumours that were not pre-treated with BrdU. The sensitivity of both total and Q cells, especially of Q cells, was significantly reduced with RDRI compared with CDRI. Combination of TPZ increased the sensitivity of both populations, with a slightly more remarkable increase in Q cells. Furthermore, the continuous administration of TPZ raised the sensitivity of both total and Q cell populations, especially the former, more markedly than the single administration, whether combined with CDRI or RDRI using gamma-rays or thermal neutrons. From the viewpoint of solid tumour control as a whole, including intratumour Q-cell control, the use of TPZ, especially when administered continuously, combined with RDRI, is useful for suppressing the reduction in the sensitivity of tumour cells caused by the decrease in irradiation dose rate in vivo.

Animals↗
PubMed2006

Hypoxia accelerates cancer invasion of hepatoma cells by upregulating MMP expression in an HIF-1alpha-independent manner.

Tumor hypoxia has been reported to induce tumor progression in several carcinomas. Current studies have shown that hypoxia inducible factor-1alpha (HIF-1alpha) is stabilized under hypoxic conditions and transactivates various genes related to cancer aggressiveness. In the present study, we examined whether hypoxia affects cancer invasion in hepatocellular carcinoma. We aimed to solve the molecular mechanism of tumor invasion under the hypoxic condition. We showed that tumor hypoxia accelerated cancer invasion in two hepatoma cell lines. Using Western blot and RT-PCR analyses we demonstrated striking evidence that the expression of HIF-1alpha, ETS-1, MMP-7 and MT1-MMP was strongly upregulated by hypoxic stimulation. To examine whether these invasion-related genes are regulated by HIF-1alpha, we treated hepatoma cells with TX-402, which was reported to repress HIF-1alpha expression. HIF-1alpha expression was strongly repressed by the TX-402 treatment. In contrast, the expression of ETS-1, MMP-7 and MT1-MMP mRNA was not affected by TX-402 treatment. We further established stable transfectants in which HIF-1alpha dominant negative vector was introduced into Hep3B cells (pHIF-1alphaDN). In the pHIF-1alphaDN cells, the expression of ETS-1, MMP-7 and MT1-MMP was not repressed. Moreover, the invasion activity of pHIF-1alphaDN was not altered, compared with that of the mock. In hepatoma cells, we provided evidence that hypoxic stress accelerates cancer invasion by upregulating ETS-1 and the MMP family by an HIF-1alpha-independent pathway.

Carcinoma, Hepatocellular↗
PubMed2005

Development of a practical immunochromatographic test with recombinant P50 for the diagnosis of Babesia gibsoni infection in dogs.

An immunochromatographic test (ICT), using recombinant truncated P50 (P50t), for the detection of antibodies to Babesia gibsoni was developed and evaluated. Whereas all sera from specific pathogen-free dogs were clearly negative, all sera from dogs experimentally infected with B. gibsoni were clearly positive in the ICT. In addition, the ICT detected no cross-reactivity with sera from dogs experimentally infected with closely related parasites, B. canis canis, B. canis vogeli, and B. canis rossi, or with Neospora caninum, and Leishmania infantum. Sequential sera from a dog experimentally infected with B. gibsoni were tested with the ICT; it was shown that the specific antibodies are detectable as early as 6 days post-infection (p.i.) and that strong antibody responses remained until the end of the experiment (144 days p.i.). To evaluate the clinical application of the ICT, a total of 54 serum samples collected from domestic dogs that had been identified as having signs of anaemia at veterinary hospitals in Japan, were tested with the ICT, the previously established enzyme-linked immunosorbent assay (ELISA) and with the indirect fluorescent antibody test (IFAT). Twenty-four of the tested samples (44.4%) were positive in both ICT and ELISA, and (51.8%) in IFAT. The concordance between ELISA and ICT was found to be 100%, and 85.7% with IFAT. Taken together, the results above suggest that the ICT using P50t is rapid, simple, accurate, and suitable for use at clinical sites for the diagnosis of B. gibsoni infection in dogs.

Animals↗
PubMed2005

The usefulness of continuous administration of hypoxic cytotoxin combined with mild temperature hyperthermia, with reference to effects on quiescent tumour cell populations.

To evaluate the usefulness of continuous administration of hypoxic cytotoxins in terms of targeting acute hypoxia in solid tumours and the significance of combination with mild temperature hyperthermia (MTH) (40 degrees C, 60 min), the cytotoxic effects of singly or continuously administered tirapazamine (TPZ) and TX-402 were examined in combination with or without MTH in vivo. Further, the effects were also analysed on total (=proliferating (P)+quiescent (Q)) and Q cell populations in solid tumours with the method for selectively detecting the Q cell response. C3H/He mice bearing SCC VII tumours received a continuous administration of 5-bromo-2'-deoxyuridine (BrdU) for 5 days to label all P cells. The tumour-bearing mice then received a single intra-peritoneal injection or 24 h continuous subcutaneous infusion of hypoxic cytotoxin, TPZ or TX-402, with or without MTH. On the other hand, to detect the changes in the hypoxic fraction (HF) in the tumours by MTH, another group of mice with or without MTH received a series of test doses of gamma-rays while alive or after tumour clamping. After each treatment, the tumour cells were isolated and incubated with a cytokinesis blocker (=cytochalasin-B) and the micronucleus (MN) frequency in cells without BrdU labelling (=Q cells) was determined using immunofluorescence staining for BrdU. The MN frequency in total tumour cells was determined from the tumours that were not pre-treated with BrdU. The sensitivity to TX-402 was slightly higher than that to TPZ in both total and Q tumour cells. Continuous administration elevated the sensitivity of both total and Q cells, especially total cells. MTH raised the sensitivity of Q cells more remarkably than that of total cells in both single and continuous administrations. It was thought to be probably because of the higher dose distribution of hypoxic cytotoxin in intermediately hypoxic areas derived mainly from chronic hypoxia through MTH. From the viewpoint of tumour control as a whole including both total and Q tumour cells, the continuous administration of hypoxic cytotoxin combined with MTH may be useful for sensitizing tumour cells in vivo.

Animals↗
PubMed2005

Toxoplasma gondii antigens GRA1 (p24) and SAG1 (p30): a comparison of their stimulatory influence on T-cell activation and cytokine expression in in vitro cultures.

The influence of recombinant cell surface SAG1 (rp30) and secretory GRA1 (rp24) antigens (Ag) on T-cell activation and cytokine induction in vitro was compared. T-cell activity and the level of IFN-gamma, IL-10 and IL-12 expression in rp30-immunized T cells were considerably increased in the presence of rp30 Ags. IgG2a and IgG1 antibodies (Ab) were detected in sera of rp24- and rp30-immunized mice, with the secretory rp24 Ag having induced significantly higher titer of IgG1 Ab. In vitro, the greater antigenicity of surface rp30 Ag was notable based on the level of T-cell activation, and cytokine synthesis suggestive of the participation of Th1 cells. Although, IFN-gamma expression by rp24 Ag was lower compared to rp30 Ag, the synthesis of both IgG2a and IgG1 Abs reflects the protective nature of rp24 Ag. We have generated two recombinant Toxoplasma gondii Ags that demonstrated differences in antigenicity in vitro. It would be interesting to evaluate the mechanism(s) of immunity induced by SAG1 (p30) and GRA1 (p24) Ags against infection with T. gondii in vivo.

Adenosine Triphosphate↗
PubMed2005

Role of homologous recombination in the alpha-particle-induced bystander effect for sister chromatid exchanges and chromosomal aberrations.

The bystander effect for sister chromatid exchanges (SCEs) and chromosomal aberrations was examined in hamster cell lines deficient in either DNA-PKcs (V3 cells, deficient in nonhomologous end joining, NHEJ) or RAD51C (irs3 cells, deficient in homologous recombination, HR). Cells synchronized in G0/G1 phase were irradiated with very low fluences of alpha particles such that < 1% of the nuclei were traversed by an alpha particle. Wild-type cells showed a prominent bystander response for SCE induction; an even greater effect was observed in V3 cells. On the other hand, no significant induction of SCE was observed in the irs3 RAD51C-deficient bystander cells irradiated at various stages in the cell cycle. Whereas a marked bystander effect for chromosomal aberrations occurred in V3 cells, the induction of chromosomal aberrations in irs3 bystander cells was minimal and similar to that of wild-type cells. Based on these findings, we hypothesize that HR is essential for the induction of SCE in bystander cells; however, HR is unable to repair the DNA damage induced in NHEJ-deficient bystander cells that leads to either SCE or chromosomal aberrations.

Alpha Particles↗
PubMed2004

The usefulness of 2-nitroimidazole-sodium borocaptate-10B conjugates as 10B-carriers in boron neutron capture therapy.

We evaluated the usefulness of five new (10)B-compounds (TX-2016, TX-2017, TX-2018, TX-2041, and TX-2042) as (10)B-carriers in boron neutron capture therapy (BNCT). They are 2-nitroimidazole-sodium borocaptate-(10)B (BSH) conjugates, that is, hybrid compounds that have both hypoxic tumor cell sensitizing unit under gamma-ray irradiation, 2-nitroimidazoles, and thermal neutron-sensitizing unit, BSH. (10)B distribution analyses in tumors and blood indicated that TX-2041 has the most favorable characteristics for localizing a sufficient amount of (10)B into tumors and keeping the (10)B concentration high during neutron beam irradiation. In addition, TX-2041 showed a significantly higher radio-sensitization effect with reactor thermal neutron beams than BSH on both total (=proliferating (P) + quiescent (Q)) and hypoxia-rich Q cell populations in solid tumors. Further, TX-2041 clearly demonstrated a radio-sensitization effect with gamma-rays on both cell populations, which could never be achieved by BSH. (10)B-carriers with a hypoxic tumor cell-sensitizing effect on tumors with gamma-rays as well as the potential to selectively localize and keep (10)B in tumors, such as TX-2041, are promising for use in actual BNCT.

Animals↗
PubMed2004

Natural IgM antibodies in sera from various animals but not the cat kill Toxoplasma gondii by activating the classical complement pathway.

Sera from swine, rabbit, and dog, that had never been exposed to Toxoplasma gondii, demonstrated significant killing of T. gondii tachyzoites in vitro, while cat serum did not. Swine and rabbit sera contained natural IgM antibody against the tachyzoites, and the classical complement pathway was activated by the binding of natural IgM antibody to the tachyzoites, leading to lysis. Anti-T. gondii antibodies, induced in swine or cat infected with T. gondii, had no killing effect by themselves but killed the tachyzoites in the presence of swine complement. However, the anti-T. gondii antibodies of swine or cat demonstrated a very low killing effect in the presence of cat complement. This suggests that T. gondii tachyzoites have an evasion mechanism to prevent lysis which is specific for cat complement.

Animals↗
PubMed2004

SAG1 is a host-targeted antigen for protection against toxoplasma gondii infection.

We previously reported that SAG1 transgenic (tg) mice have an elevated susceptibility resulting from their inability to elicit strong Th1-based protection against Toxoplasma gondii infection. Here, we demonstrate that SAG1 tg mice were protected against T. gondii infection, characterized by a decline in IFN-gamma levels, following administration of a lethal dose of T. gondii. Moreover, immunization with T. gondii homogenate conferred protection and induced production of IgG, with IgG1 and IgG2a subclasses driven by Th2 and Th1 responses, respectively, in both SAG1 tg and wild-type (wt) mice. IgG titers were significantly higher from day 10 after immunization in wt mice compared to those in SAG1 tg mice. There were no significant differences observed in levels of IgG1 in both groups. However, significantly lower IgG2a titers were measured in the sera from SAG1 tg mice on days 10, 15 and 20. IFN-gamma levels in sera were significantly lower in SAG1 tg mice compared to those in wt mice on day 20 after immunization. When challenged with a lethal dose of the Beverley strain of T. gondii, 80 and 100% survival rates were observed in SAG1 tg and wt mice, respectively, indicating that SAG1 tg mice were protected to a lesser extent from challenge due to the decrease in protective immunity. These results suggest that SAG1 plays a critical role in eliciting protection, hence a target antigen for the development of protective Th1-based responses against T. gondii infection in mice.

Animals↗
PubMed2004

[Successful staged repair of a symptomatic neonate of tetralogy of Fallot with severe absent pulmonary valve syndrome].

Tetralogy of Fallot with absent pulmonary valve has been classified to a few groups. The most severe one is characterized by symptomatic onset immediately after birth. The others are no or slightly symptomatic at least during their neonatal period. In a severely symptomatic 12-day-old neonate of tetralogy of Fallot with absent pulmonary valve who had required intubation immediately after birth, tight pulmonary banding and left side modified Blalock-Taussig shunt were performed on emergency basis. Consequently, prior massive pulmonary regurgitation was decreased significantly. Forty-five days after this first stage operation, he weaned from respiratory management. At 1-year-old, radical repair based on conotruncal repair, which consisted of patch closure of ventricular septal defect preserving the tricuspid septal leaflet function, resection of anterior wall of enlarged left pulmonary artery, and right ventricular outflow tract reconstruction using autologous tissue and a pericardial patch was performed. Bicuspid pulmonary valve, posterior one of procured autologous pulmonary wall and anterior one of polytetrafluoroethylene (PTFE) respectively, was created to minimize deterioration of the pulmonary insufficiency. Although postoperative cardiac function was kept feasible showing his central venous pressure of 7 mmHg in the main, postoperative general course was eventful especially regarding the respiratory function. The patient was weaned from the prolonged ventilator management 5 months after this radical repair eventually. Generally, to diminish the massive pulmonary regurgitation in early lifetime period could reduce a progressive airway obstruction and minimize pulmonary tissue damage. However, even after the total correction in this case, considerable peripheral segmental pulmonary obstructive lesions were persistent according to the perfusion lung scanning with 99mTc macroaggregated albumin and 99mTechnegas ventilation lung scanning studies. This persistent, supposed to be innate, pulmonary obstructive lesions might prevent ordinal recovery after cardiac radical repair for this most severe subtype of absent pulmonary valve syndrome.

Blood Vessel Prosthesis Implantation↗
PubMed2003

A novel hypoxia-dependent 2-nitroimidazole KIN-841 inhibits tumour-specific angiogenesis by blocking production of angiogenic factors.

Tumour angiogenesis is initiated by angiogenic factors that are produced in large amounts by hypoxic tumour cells. The inhibition of this step may lead to tumour-specific antiangiogenesis because normal tissues are not usually hypoxic. On the other hand, blocking a biological function of endothelial cells is known to result in angiogenic inhibition. To produce a tumour-specific and powerful antiangiogenesis, we determined whether potent angiogenic inhibition could be achieved by inhibiting the production of angiogenic factors by hypoxic tumour cells and simultaneously blocking certain angiogenic steps in endothelial cells under normoxia. We focused on the 2-nitroimidazole moiety, which is easily incorporated into hypoxic cells and exhibits its cytotoxicity as hypoxic cytotoxin. We designed and synthesised 2-nitroimidazole derivatives designated as KIN compounds, and investigated their antiangiogenic activities under normoxia using a chick embryo chorioallantoic membrane. KIN-841 (2-nitroimidazole 1-acetylhydroxamate) showed a potent angiogenic inhibition in a dose-dependent manner. This compound inhibited the proliferation of bovine pulmonary arterial endothelial (BPAE) cells more strongly than that of tumour cells, such as Lewis lung carcinoma (3LL) cells, under normoxia. The inhibition of cell proliferation by KIN-841 under hypoxia increased about five-fold compared to that under normoxia. Moreover, under hypoxia, KIN-841 significantly decreased the excessive production of vascular endothelial cell growth factors induced by 3LL cells as determined by tritium-labelled thymidine ([(3)H]thymidine) incorporation into BPAE cells and by ELISA. Intraperitoneal administration of KIN-841 suppressed 3LL-cell-induced in vivo angiogenesis in the mouse dorsal air sac system. These results indicate that the regulation of the production of angiogenic factors by hypoxic tumour cells is a useful target for tumour-specific angiogenesis inhibition, and that KIN-841, which causes simultaneous direct inhibition of endothelial cell function and production of angiogenic factors by hypoxic tumour cells, is a very potent inhibitor of tumour-specific angiogenesis. Thus, the potential for clinical use of KIN-841 as an antitumour drug is very high.

Angiogenesis Inhibitors↗
PubMed2003

Differing effects of breast cancer 1, early onset (BRCA1) and ataxia-telangiectasia mutated (ATM) mutations on cellular responses to ionizing radiation.

PURPOSE: The ataxia-telangiectasia mutated (ATM) gene encodes a protein kinase, the activation of which is an early event in the cellular response to ionizing radiation. One of the many substrates of ATM is BRCA1 (breast cancer 1, early onset gene), which has been associated with susceptibility to breast and ovarian cancer, and has been implicated in DNA repair processes. Various cellular responses to radiation were analysed in cells with mutations in ATM or BRCA1 in an attempt to clarify which effects of ATM can be mediated through BRCA1. MATERIALS AND METHODS: The response to radiation of cells with mutations in ATM or BRCA1 was examined, as were BRCA1-mutant tumour cells transfected with an exogenous wild-type BRCA1 allele. Assays included cell-survival curves, studies of potentially lethal damage repair, measurement of chromosomal aberrations and of G1 arrest, and Western blot analysis of lysates of irradiated cells to determine the phosphorylation of the product of the human Mdm2 gene (HDM2). RESULTS: Both ATM and BRCA1 mutations were associated with sensitivity to ionizing radiation, deficient repair of potentially lethal damage and markedly increased chromosomal aberrations. A BRCA1-mutated tumour cell line HCC1937, like ATM mutant cells, did not exhibit a normal G1 arrest but, unlike ATM mutant cells, did exhibit phosphorylation of HDM2. Expression of wild-type BRCA1 in HCC1937 cells partially restored radioresistance, restored repair of potentially lethal damage and markedly reduced radiation-induced chromosomal aberrations. G1 arrest, however, was not restored by expression of BRCA1. CONCLUSIONS: The results are consistent with a model in which ATM phosphorylation of BRCA1 regulates DNA repair functions, particularly those involved in potentially lethal damage repair and chromosomal integrity, but not other aspects of the cellular response to radiation such as G1 cell cycle arrest. To the authors' knowledge, this is the first demonstration of the ability of exogenously expressed BRCA1 to restore the ability to perform potentially lethal damage repair and maintain chromosomal integrity in irradiated cells.

Ataxia Telangiectasia Mutated Proteins↗
PubMed2003

Increased bystander mutagenic effect in DNA double-strand break repair-deficient mammalian cells.

PURPOSE: We have shown previously that when monolayer cultures of Chinese hamster ovary (CHO) cells are exposed to very low fluences of alpha-particles, HPRT mutations are induced in non-irradiated 'bystander' cells in the population. The present investigation was designed to examine the role of DNA repair in this process. MATERIALS AND METHODS: The DNA double-strand repair-deficient mutant cell line xrs-5 was exposed to mean doses of alpha-particles as low as 0.04 cGy whereby less than 1% of the nuclei were traversed by an alpha track and thus received any radiation exposure. RESULTS: With this very low alpha-particle fluence, most of the cells in the xrs-5 population appeared to be at risk for the induction of mutations, indicating a much larger bystander effect than observed with wild-type CHO cells. Molecular structural analyses showed that xrs-5 mutants primarily involved partial and total gene deletions as opposed to wild-type cells where point mutations predominated in bystander cells. CONCLUSIONS: These results indicate a very large bystander effect in xrs-5 cells. They support the hypothesis that unrepaired or misrepaired double-strand breaks (DSB), arising from opposed DNA lesions, enhance the sensitivity of bystander cells in xrs-5 cultures to the induction of mutations.

Alpha Particles↗
PubMed2002

Bystander effects: intercellular transmission of radiation damage signals.

Biological effects were examined in confluent cultures of fibroblasts and epithelial cells exposed to very low mean doses of alpha radiation, doses by which only 1-2% of the cells were actually traversed by an alpha particle. Enhanced frequencies of sister chromatid exchanges and HPRT mutations occurred in the non-irradiated, 'bystander' cells associated with a similar increase in the frequency of micronuclei, indicating the induction of DNA damage in these cells. In order to gain information concerning molecular pathways, changes in gene expression were examined in bystander cells by western analysis and in situ immunofluorescence staining. The expression levels of p53, p21 and MDM2 were significantly modulated in bystander cells; the damage signals leading to these changes were transmitted from irradiated to bystander cells by gap junction mediated intercellular communication. The bystander response was suppressed by incubation with superoxide dismutase as well as an inhibitor of NADPH oxidase, suggesting the effect may be mediated by oxidative stress. To examine other signalling pathways responsive to oxidative stress, the activation of stress-related kinases and their downstream transcription factors were analysed in bystander cells by western blotting and electrophoretic mobility shift assays; a 2-4-fold increase in the phosphorylation levels of JNK, ERK1/2, p90RSK, Elk-1 and ATF2 was observed. These changes were detected by 15 min after irradiation and persisted for at least 1 h. These findings indicate the activation of multiple signal transduction pathways in bystander cells, involving signals arising from the plasma membrane as well as from DNA damage.

Animals↗
PubMed2002

Development and evaluation of an enzyme-linked immunosorbent assay with recombinant SAG2 for diagnosis of Toxoplasma gondii infection in cats.

Cats are pivotal in the transmission of Toxoplasma gondii. To develop a sensitive and specific serodiagnostic method for feline toxoplasmosis, surface antigen 2 (SAG2) of T. gondii was expressed in Escherichia coli and its diagnostic potential evaluated in an enzyme-linked immunosorbent assay (ELISA). The ELISA with recombinant SAG2 (rSAG2) was able to differentiate very clearly between sera from cats experimentally infected with T. gondii and sera from normal cats. Serum samples collected from domestic cats in Japan were investigated by the ELISA, and the results were compared with those of a commercially available latex agglutination test (LAT) kit. Of the 192 samples screened, 42 (21.9%) were positive by ELISA. Among the 42 ELISA-positive samples, 39 were positive by LAT. There was a significant correlation between ELISA and LAT titers. All the 150 ELISA-negative samples were negative by LAT. These results indicate that the ELISA with rSAG2 expressed in E. coli should be a useful method for detection of T. gondii infection in cats.

Animals↗
PubMed2001

Molecular evidence of Babesia caballi (Nuttall and Strickland, 1910) parasite transmission from experimentally-infected SCID mice to the ixodid tick, Haemaphysalis longicornis (Neuman, 1901).

Molecular evidence that suggests the possible role of the ixodid tick, Haemaphysalis longicornis and its eggs in the transmission of equine Babesia caballi parasites is presented herein. Using polymerase chain reaction (PCR) to assay for DNA in parasites, presumably acquired by ticks that were allowed to feed on splenectomized-SCID mice, experimentally exposed to in vitro-cultivated B. caballi, we have obtained positive bands that corresponded to the expected B. caballi-specific 430bp gene fragment in 50% of female ticks used, and in 75 and 25% of eggs and larval progeny, respectively. Also, parasite DNA was detected in ticks, eggs and larvae as late as the 16th to the 20th day post-host infestation. Present findings support to the potential role of H. longicornis in the transmission of B. caballi parasites. Its capability, however, to successfully transmit the infection to horses under natural conditions in the field needs to be further ascertained. To our knowledge, this is the first documented study incriminating H. longicornis as a most and likely biological vector of equine babesias.

Animals↗
PubMed2001

Serodiagnosis of Toxoplasma gondii infection in cats by enzyme-linked immunosorbent assay using recombinant SAG1.

The gene encoding surface antigen 1 (SAG1, P30) of Toxoplasma gondii (T. gondii) was cloned into the plasmid pGEX-4T-3 and subsequently expressed in Escherichia coli (E. coli) as a glutathione-S-transferase (GST) fusion protein. The recombinant SAG1 (rSAG1) was refolded using 8M urea solution followed by dialysis and thereafter evaluated in an enzyme-linked immunosorbent assay (ELISA) for serological diagnosis of toxoplasmosis. The test sera were adsorbed with GST to block non-specific reactivity to the GST-SAG1 fusion protein. The ELISA with rSAG1 was able to differentiate very clearly between sera from cats or mice experimentally infected with T. gondii and sera from normal cats or mice. The ELISA detected no cross-reactivity with sera from mice experimentally infected with the closely related parasite Neospora caninum (N. caninum). Some 193 cat sera were tested for antibodies to T. gondii, out of which 40 (20.7%) reacted positively by ELISA with the rSAG1 while another 79.3% cats reacted negative to the assay. Both positive and negative sera were confirmed by Western blot analysis. The results of ELISA were in agreement with those of a commercially available latex agglutination test (LAT) kit, although the former had higher titers than the latter.

Animals↗