Browsing by Author "Saito, T."
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Item Native SAG1 in Toxoplasma gondii lysates is superior to recombinant SAG1 for serodiagnosis of T. gondii infections in chickens(Parasitology International, 2019-04) Appiah-Kwarteng, C.; Saito, T.; Toda, N.; Kitoh, K.; Nishikawa, Y.; Adenyo, C.; Kayang, B.; Owusu, E.O.; Ohya, K.et.al.Toxoplasma gondii can infect almost all mammals and birds, including chickens. The aim of this study was to identify an appropriate immunogenic antigen for serodiagnosis of T. gondii infections in chickens. We examined serum samples from chickens that were intravenously or intraperitoneally infected with 106–108 tachyzoites of T. gondii strains PLK, RH, CTG, ME49 or TgCatJpGi1/TaJ using enzyme-linked immunosorbent assays (ELISAs), latex agglutination tests (LATs) and western blotting. Regardless of parasite strain or infection dose and route, the commercial LAT was positive for almost all sera collected 1 week post-infection. However, at 2 weeks post-infection, LATs were negative in the same birds. ELISAs using the Escherichia coli-produced recombinant T. gondii antigens SAG1 and GRA7 showed strong signals at 1–2 weeks post infection, but thereafter diminished for the majority of serum samples. In contrast, western blotting against crude tachyzoite antigens showed a persistent band up to 4 weeks post-infection. Sera from these chickens reacted much more strongly with SAG1 from crude tachyzoite antigens than with recombinant SAG1. Even in experimentally-infected birds whose parasite burdens in tissue were undetectable, sera still reacted with native SAG1. We tested sera from free-range chickens on a small farm in Ghana, Africa, using western blotting and found that the serum of one bird reacted with a single band of approximately 27 kDa, the putative molecular weight of SAG1. Thus we conclude that native SAG1, but not E. coli-produced recombinant SAG1, is suitable for serodiagnosis of T. gondii infections in chickens.Item Prevalence of hepatitis G virus and characterization of viral genome in Ghana.(Hepatology Research, 1999) Saito, T.; Ishikawa, K.; Osei-Kwasi, M.; Kaneko, T.; Brandful, J.A.M.; Nuvor, V.; Aidoo, S.; Ampofo, W.; Apeagyei, F.A.; Ansah, J.E.; Adu-Sarkodie, Y.; Nkrumah, F.K.; Abe, K.The prevalence of hepatitis G virus (HGV) infection was investigated in 85 human immunodeficiency virus (HIV)-infected and 30 uninfected individuals' sera obtained from Ghanaians. HGV RNA in serum was identified by a nested reverse transcription polymerase chain reaction (RT-PCR) using primers derived from the 5′-noncoding region. We also tested for hepatitis C virus by nested RT-PCR and for hepatitis B surface antigen (HBsAg) by passive hemagglutination method. HGV RNA was detected in 17 of 85 (20%) HIV sero-positive and three of 30 (10%) sero-negative Ghanaians, respectively. The prevalence of HGV infection was much greater than hepatitis C (0.9%) and hepatitis B virus (7.8%) infections in the present study. Ninety four percent of HGV infected patients were seronegative for hepatitis B and C virus infections. The nine different Ghanaian isolates in the 5′-untranslated region of the HGV genome had one nucleotide deletion at the same position when compared with other HGV isolates. Phylogenetic analysis showed that all Ghanaian isolates belonged to type 1 (West Africa type) of the HGV genotypes. Moreover, we determined nearly full-length nucleotide sequence of the HGV genome (denoted HGV-GA128) recovered from a Ghanaian infected with HIV. The HGV-GA128 was composed of 9231 nucleotides and had a single open reading frame, encoding 2843 amino acid residues. This isolate differed from previously reported HGV/GBV-C isolates by 10–15% of the nucleotide sequence and 2–5% of the amino acid sequence. Our data indicate a high prevalence of HGV, especially genotype 1, in Ghana.