Biomedical subjects

Shin-Ru Shih

Publications and source records attributed to Shin-Ru Shih.

29 records · Page 2Linked to original sources

PubMed2004

Influenza A virus PB1-F2 gene in recent Taiwanese isolates.

Influenza A virus contains eight RNA segments and encodes 10 viral proteins. However, an 11th protein, called PB1-F2, was found in A/Puerto Rico/8/34 (H1N1). This novel protein is translated from an alternative open reading frame (ORF) in the PB1 gene. We analyzed the PB1 gene of 42 recent influenza A isolates in Taiwan, including 24 H1N1 and 18 H3N2 strains. One H1N1 isolate and 17 H3N2 isolates contained the entire PB1-F2 ORF of 90 residues, three amino acids (aa) longer than the PB1-F2 of A/Puerto Rico/8/34 at the C terminal. The one remaining H3N2 isolate encoded a truncated PB1-F2 with 79 residues. The other 23 H1N1 isolates contained a truncated PB1-F2 of 57 aa. Phylogenetic analysis of both the HA and the PB1 genes showed that they shared similar clustering of these Taiwanese isolates, suggesting that no obvious reassortment occurred between the two genomic segments.

Amino Acid Sequence↗

PubMed2003

Inhibition of enterovirus 71-induced apoptosis by allophycocyanin isolated from a blue-green alga Spirulina platensis.

Enterovirus 71 infection causes significant morbidity and mortality in children, yet there is no effective treatment. In this study, a protein-bound pigment, allophycocyanin purified from blue-green algae is first reported to exhibit anti-enterovirus 71 activity. Allophycocyanin neutralized the enterovirus 71-induced cytopathic effect in both human rhabdomyosarcoma cells and African green monkey kidney cells. The 50% inhibitory concentration of allophycocyanin for neutralizing the enterovirus 71-induced cytopathic effect was approximately 0.045 +/- 0.012 microM in green monkey kidney cells. The cytotoxic concentrations of allophycocyanin for rhabdomyosarcoma cells and African green monkey kidney cells were 1.653 +/- 0.003 microM and 1.521 +/- 0.012 microM, respectively. A plaque reduction assay showed that the concentrations of allophycocyanin for reducing plaque formation by 50% were approximately 0.056 +/- 0.007 microM and 0.101 +/- 0.032 microM, when allophycocyanin were added at the state of viral adsorption and post-adsorption, respectively. Antiviral activity was more efficient in cultures treated with allophycocyanin before viral infection compared with that in the cultures treated after infection. Allophycocyanin was also able to delay viral RNA synthesis in the infected cells and to abate the apoptotic process in enterovirus 71-infected rhabdomyosarcoma cells with evidence of characteristic DNA fragmentation, decreasing membrane damage and declining cell sub-G1 phase. It is concluded that allophycocyanin possesses antiviral activity and has a potential for development as an anti-enterovirus 71 agent.

Antiviral Agents↗

PubMed2003

Serotype-specific detection of enterovirus 71 in clinical specimens by DNA microchip array.

Enterovirus 71 is an important pathogen that causes high morbidity and mortality in children in Taiwan. Virus isolation in cell cultures has been the standard method for enterovirus 71 identification in Clinical Virology Laboratories. However, virus isolation takes 5-10 days when using cell culture. A microchip for enterovirus 71 detection was developed as an alternative diagnostic method. The novel approach is based on hybridization of amplified DNA specimens with oligonucleotide DNA probes immobilized on a microchip. Two oligonucleotides were used as detection probes, the pan-enterovirus sequence located in the 5'-noncoding region (5'-NCR) and the enterovirus 71-specific sequence located in the VP2 region. The diagnostic procedure takes 6 h. One hundred specimens identified as enteroviruses by viral cultures were tested using this microchip, including 67 enterovirus 71 specimens. The sensitivity of the novel method is 89.6% and its specificity is 90.9%. The enterovirus 71-microchip can detect the amplicon derived from viral RNA corresponding to 1-10 virions in a clinical specimen. Microchip array is a potential diagnostic method for identification of enterovirus in the future.

5' Untranslated Regions↗

PubMed2002

Characterization of a Vero cell-adapted virulent strain of enterovirus 71 suitable for use as a vaccine candidate.

Enterovirus 71 (EV71) is a neurotrophic virus that causes seasonal morbidity and mortality in children throughout the world with increasing frequency in recent years. Because of the lack of an effective antiviral agent, primary prevention, including the development of effective vaccines, is a top priority in terms of control strategies. Poliovirus vaccine technology, both live attenuated and inactivated, killed virus vaccines, can be adopted for use with EV71 because of their relatedness. In this study, we have characterized a laboratory-adapted EV71 strain, YN3-4a, which exhibits different characteristics from those of its parent isolate, neu, in having a rapid growth rate in Vero cells, a larger plaque size, and a lower LD(50) in newborn mice. The YN3-4a can be produced at a high viral titer of up to 10(10) tissue culture infective dose (TCID(50)) when grown in Vero cells, an approved substrate for virus vaccine production. Mouse antiserum raised against YN3-4a can neutralize a broad range of strains of EV71 isolated at different times from a variety of geographic regions. On passage in Vero cells, YN3-4a remained genetically and phenotypically stable. Many of the above-described features, such as high viral yield, strong immunogenicity, broad-based antigenic coverage, and passage stability, are desirable features in a prototype virus for the development of an inactivated viral vaccine.

Animals↗

PubMed2002

The 1998 enterovirus 71 outbreak in Taiwan: pathogenesis and management.

The most recently discovered enterovirus, enterovirus 71 (EV71), is neurotropic and may cause severe disease and sudden death in children. In 1998, a large outbreak of enterovirus infection occurred in Taiwan that resulted in 405 severe cases in children and 78 deaths. Of the 78 children who died, 71 (91%) were <5 years old. EV71 was the primary agent in fatal cases of infection. Most of these patients died within 1-2 days of admission to the hospital. We hypothesize that EV71 directly attacks the central nervous system and causes neurogenic pulmonary edema and cardiac decompensation through the mechanism of sympathetic hyperactivity and inflammatory responses. Early recognition of risk factors and intensive care are crucial to successful treatment of this fulminant infection. After poliovirus is eradicated, EV71 will become the most important enterovirus that affects children, and development of a vaccine may be the only effective measure against it.

Convalescence↗

PubMed2002

Design, synthesis, and structure-activity relationship of pyridyl imidazolidinones: a novel class of potent and selective human enterovirus 71 inhibitors.

When skeletons of Win compounds were used as templates, computer-assisted drug design led to the identification of a novel series of imidazolidinone derivatives with significant antiviral activity against enterovirus 71 (EV 71), the infection of which had resulted in about 80 fatalities during the 1998 epidemic outbreak in Taiwan. In addition to inhibiting all the genotypes (A, B, and C) of EV 71 in the submicromolar to low micromolar range, compounds 1 and 8 were extensively evaluated against a variety of viruses, showing potent activity against coxsackievirus A9 (IC(50) = 0.47-0.55 microM) and coxsackievirus A24 (IC(50) = 0.47-0.55 microM) as well as moderate activity against enterovirus 68 (IC(50) = 2.13 microM) and echovirus 9 (IC(50) = 2.6 microM). Our SAR studies revealed that imidazolidinone analogues with an aryl substituent at the para position of the phenoxyl ring, such as compounds 20, 21, 27, 57, 58, and 61, in general exhibited the highest activity against EV 71. Among them, compound 20 and its corresponding hydrochloride salt 57, in terms of potency and selectivity index, appear to be the most promising candidates in this series for further development of anti-EV-71 agents. Preliminary results of the study on the mode of action by a time-course experiment suggest that test compounds 1 and 8 can effectively inhibit the virus replication at the early stages, referring to virus attachment or uncoating. This indicates that the surface protein may be the target for this type of compounds.

Animals↗

PubMed2002

The 3C protease activity of enterovirus 71 induces human neural cell apoptosis.

The human glioblastoma SF268 cell line was used to investigate the induction of apoptosis by the 3C protease of enterovirus 71 (EV71). Transient expression in these cells of the wild-type 3C protein encoded by EV71 induced morphological alterations typical of apoptosis, including generation of apoptotic bodies. Degradation of cellular DNA in nucleosomes was also observed. When two of the amino acids in the catalytic motif of 3C were changed by mutagenesis, the 3C protein not only lost its proteolytic activity, but also its ability to induce apoptosis in the SF268 cells. Twenty-four hours after 3C transfection, poly(ADP-ribose) polymerase, a DNA repair enzyme, was cleaved, indicating that caspases were activated by the expression of EV71 3C. The 3C-induced apoptosis was blocked by the caspase inhibitors DEVD-fmk and VAD-fmk. Our findings suggest that the proteolytic activity of 3C triggers apoptosis in the SF268 cells through a mechanism involving caspase activation and that this apoptotic pathway may play an important role in the pathogenesis of EV71 infection.

3C Viral Proteases↗

PubMed2002

Responses of IgM for enterovirus 71 infection.

A rapid serological assay was developed for detection of specific IgM to enterovirus 71, a human picornavirus that is usually associated with severe central nervous system complications. The sensitivity and specificity of this "in-house" mu-capture enzyme linked-immunosorbent assay was assessed by testing 213 serum samples. With the conventional virus culture as a standard method, the sensitivity and specificity were 91.5 and 93.1%, respectively, for this newly developed immunoassay. This method allows for detection of the IgM responses from the patients either infected by genotype B or genotype C of enterovirus 71. IgM can be detected as early as the second day from the onset of disease. IgM responses exhibit 100% positive rate from enterovirus 71-infected patients with complications, including encephalitis, meningitis, polio-like syndrome, pulmonary edema, and fatal cases. These findings suggest that detection of specific IgM by the use of enzyme linked-immunosorbent assay is a rapid and valuable way for the diagnosis of enterovirus 71 infection.

Antibodies, Viral↗

PubMed2002

Risk factors of enterovirus 71 infection and associated hand, foot, and mouth disease/herpangina in children during an epidemic in Taiwan.

OBJECTIVE: In 1998, an enterovirus 71 (EV71) epidemic in Taiwan was associated with hand, foot, and mouth disease (HFMD)/herpangina and involved 78 fatal cases. We measured EV71 seroprevalence rates before and after the epidemic and investigated risk factors associated with EV71 infection and illness. METHODS: Neutralizing antibodies to EV71 were assayed for 539 people before the epidemic and 4619 people of similar ages after the epidemic. Questionnaires, which were completed during household interviews after the epidemic, solicited demographic variables, exposure history, and clinical manifestations. RESULTS: A total of 129 106 cases of HFMD were reported during the epidemic. Age-specific pre-epidemic EV71 seroprevalence rates were inversely related to age-specific periepidemic mortality rates (r = -0.82) or severe case rates (r = -0.93). Higher postepidemic EV71 seropositive rates among children who were younger than 3 years positively correlated with higher mortality rates in different areas (r = 0.88). After the epidemic, 51 (56%) of 91 younger siblings of elder siblings who were EV71-seropositive were EV71-seropositive; otherwise, 2.2% (4 of 186) of younger siblings were EV71-seropositive (matched odds ratio [OR]: 10; 95% confidence interval [CI]: 3.4-29). Stepwise multiple logistic regression revealed other factors associated with EV71 infection to be older age (adjusted OR: 2.5; 95% CI: 1.9-3.4), attendance at kindergartens/child care centers (adjusted OR: 1.8; 95% CI: 1.3-2.5), contact with HFMD/herpangina (adjusted OR: 1.6; 95% CI: 1.2-2.1), greater number of children in a family (adjusted OR: 1.4; 95% CI: 1.1-1.7), and rural residence (adjusted OR: 1.4; 95% CI: 1.2-1.6). Twenty-nine percent of preschool children who were infected with EV71 developed HFMD/herpangina. Younger age and contact with HFMD/herpangina were significant factors for the development of EV71-related HFMD/herpangina in these children. CONCLUSIONS: An increased incidence of EV71 infection in young children occurred more often in geographic areas with increased mortality rates. Intrafamilial and kindergarten transmissions among preschool children were major modes of disease transmission during the widespread EV71 epidemic in Taiwan in 1998.

Child↗

PubMedDate not supplied

Mutations at KFRDI and VGK domains of enterovirus 71 3C protease affect its RNA binding and proteolytic activities.

The 3C protease (3C(pro)) of enterovirus 71 (EV71) is a good molecular target for drug discovery. Notably, this protease was found to possess RNA-binding activity. The regions responsible for RNA binding were classified as 'KFRDI' (positions 82-86) and 'VGK' (positions 154-156) in 3C(pro) by mutagenesis study. Although the RNA-binding regions are structurally distinct from the catalytic site of EV71 3C(pro), mutations in the RNA-binding regions influenced 3C(pro) proteolytic activity. In contrast, mutations at the catalytic site had almost no influence on RNA binding ability. We identified certain mutations within 3C(pro) which abrogated both the RNA-binding activity of the expressed, recombinant, protease and the ability to rescue virus from an infectious full-length clone of EV71 (pEV71). Interestingly, mutation at position 84 from Arg(R) to Lys(K) was found to retain good RNA binding and proteolytic activity for the recombinant 3C(pro); however, no virus could be rescued when pEV71 with the R84K mutation was introduced into the infectious copy. Together, these results may provide useful information for using 3C(pro) as the molecular target to develop anti-EV71 agents.

3C Viral Proteases↗

PubMedDate not supplied

Avian influenza virus: the threat of a pandemic.

The 1918 influenza A virus pandemic caused a death toll of 40 to approximately 50 million. Currently, because of the widespread dissemination of the avian influenza virus (H5N1), there is a high risk of another pandemic. Avian species are the natural hosts for numerous subtypes of influenza A viruses; however, the highly pathogenic avian influenza virus (HPAI) is not only extremely lethal to domestic avian species but also can infect humans and cause death. This review discusses why the avian influenza virus is considered the most likely candidate for the first flu pandemic of the 21st century.

Animals↗