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Tian Cheng Li

Publications and source records attributed to Tian Cheng Li.

8 recordsLinked to original sources
PubMed2005

Challenges in creating a vaccine to prevent hepatitis E.

Recombinant hepatitis E virus capsid protein (HEV CP) assembles orally immunogenic virus-like particles (VLP) when expressed in an insect cell system. We used plant expression cassettes, pHEV101 and pHEV110, for transformation of potato to express HEV CP, and 10 independent transgenic lines of HEV101 and 6 lines of HEV110 were obtained. ELISA for HEV CP was performed on tuber extracts. Accumulation of HEV CP in tubers varied from about 5 to 30 microg/g fresh tuber depending on the transgenic plant line. We further compared the expression levels with the yield of tubers for each line. Tuber yield varied less than expression levels, and ranged from about 600 to 1000 g per pot. Although Western blot showed that apparently intact HEV CP accumulated, we observed very limited assembly of virus-like particles in potato tubers. Oral immunization of mice with transgenic potatoes failed to elicit detectable anti-CP antibody response in serum, suggesting that VLP assembly is a key factor in orally delivered HEV CP vaccines.

Animals↗
PubMed2005

Structure and assembly of a T=1 virus-like particle in BK polyomavirus.

In polyomaviruses the pentameric capsomers are interlinked by the long C-terminal arm of the structural protein VP1. The T=7 icosahedral structure of these viruses is possible due to an intriguing adaptability of this linker arm to the different local environments in the capsid. To explore the assembly process, we have compared the structure of two virus-like particles (VLPs) formed, as we found, in a calcium-dependent manner by the VP1 protein of human polyomavirus BK. The structures were determined using electron cryomicroscopy (cryo-EM), and the three-dimensional reconstructions were interpreted by atomic modeling. In the small VP1 particle, 26.4 nm in diameter, the pentameric capsomers form an icosahedral T=1 surface lattice with meeting densities at the threefold axes that interlinked three capsomers. In the larger particle, 50.6 nm in diameter, the capsomers form a T=7 icosahedral shell with three unique contacts. A folding model of the BKV VP1 protein was obtained by alignment with the VP1 protein of simian virus 40 (SV40). The model fitted well into the cryo-EM density of the T=7 particle. However, residues 297 to 362 of the C-terminal arm had to be remodeled to accommodate the higher curvature of the T=1 particle. The loops, before and after the C-terminal short helix, were shown to provide the hinges that allowed curvature variation in the particle shell. The meeting densities seen at the threefold axes in the T=1 particle were consistent with the triple-helix interlinking contact at the local threefold axes in the T=7 structure.

BK Virus↗
PubMed2003

Prevalence of hepatitis virus types B through E and genotypic distribution of HBV and HCV in Ho Chi Minh City, Vietnam.

A molecular epidemiological survey of various hepatitis viral infections, including hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis D virus (HDV), was carried out in Ho Chi Minh City, Vietnam. This study included of 295 patients with liver disease (234 viral related and 61 non-viral related) and 100 healthy individuals. The infection rates of HBV and HCV in 234 liver disease patients with acute hepatitis, chronic hepatitis, liver cirrhosis and hepatocellular carcinoma, were 31.2 and 19.2%, respectively. On the other hand, detection rates of these viruses in healthy populations were 10 and 2%, respectively (P<0.005 and <0.0001, respectively). None of cases tested was positive for HDV RNA. The most common viral genotypes were type B and C of HBV (43 and 57%) and type 2a of HCV (33.3%). Surprisingly, high prevalence of HBV pre-S2 deletion mutant was found in 22 of 87 (25.3%) patients with chronic liver disease. Moreover, antibody to hepatitis E virus (HEV) immunoglobulin G (IgG) was detected in 78 of 185 (42%) and IgM in 1 of 185 (0.5%) patients. The age prevalence of anti-HEV IgG was reached 61.9% in 21-40-year-olds. These results suggest that these hepatitis viruses, except for HDV, are spreading among liver disease patients in Ho Chi Minh city, Vietnam and HBV was the most important causative agent correlated with liver disease in this area.

Journal Article↗
PubMed2003

Evidence for widespread infection of hepatitis E virus among wild rats in Japan.

Sporadic cases of hepatitis E have been reported in industrialized countries, including Japan. The source of hepatitis E virus (HEV) in these patients is unknown, although zoonotic transmission has been suggested. To investigate whether or not rodents might be a reservoir of HEV, we conducted an epidemiological survey for the antibody to a recombinant capsid protein of HEV using serum samples from wild rodents in Japan. One hundred and fourteen of 362 (31.5%) Norway rats (Rattus norvegicus) and 12 of 90 (13.3%) black rats (Rattus rattus) were positive for anti-HEV IgG. In contrast, all of the sera from 55 mice were negative for anti-HEV IgG. The rate of antibody positivity increased with weight among Norway rats. Seropositive rats were found in all five districts surveyed in this study, but the prevalence of anti-HEV IgG in wild rats differed among these prefectures. Despite the fact that Japan is a non-endemic country of hepatitis E, widespread infection of HEV was observed among wild rats in Japan. Our results suggested that HEV or a closely related virus is circulating among wild rats in Japan.

Journal Article↗
PubMed2003

Present state of hepatitis E virus epidemiology in Tokyo, Japan.

Recently studies have reported the possibility that an indigenous hepatitis E virus (HEV) exists in Japan, but the epidemiological features of HEV in Japan are inadequate to make a judgment. In order to search the present state of HEV infection in Japan, we used ELISA to test 1033 sera from residents living in Tokyo and the Tokyo suburbs, for the presence of the antibody against HEV. The positive rate of anti-HEV IgG was 15.4% in all liver disease patients (68 of 440), 3% (6/200) in healthy individuals and 0.4% in infants (1/246), respectively (P<0.01). Anti-HEV IgG was seen in 17.6% (35/199) of liver disease patients of unknown etiology; 29.4% (5/17) of fulminant hepatitis, 17% of acute hepatitis (15/88) and 16% of chronic hepatitis (15/94). Anti-HEV IgG co-existed with hepatitis B virus and hepatitis C virus in 23.6% (21/89) and 7.9% (12/152), respectively. Furthermore, the prevalence of anti-HEV IgG was significantly higher in hemodialysis patients (18/60: 30%) and hospital workers (8/87: 9.2%) than in the healthy population (P<0.01). Anti-HEV IgM was detected in 0.1% of all samples tested (1/1033). The prevalence of anti-HEV IgG increased with age. No individuals with HEV antibody had a recent history of visiting countries where hepatitis E is endemic. These results indicate that generally 15.4% of Japanese patients with liver diseases had a history of HEV infection in the past. The routes of transmission of HEV require clarification in Japan.

Journal Article↗