Laboratory-based surveillance and molecular epidemiology of influenza virus in Taiwan

A laboratory-based surveillance network of 11 clinical virological laboratories for influenza viruses was established in Taiwan under the coordination of the Center for Disease Control and Prevention (CDC), Taiwan. From October 2000 to March 2004, 3,244 influenza viruses were isolated, including 1,969 influenza A and 1,275 influenza B viruses. The influenza infections usually occurred frequently in winter in the northern hemisphere. However, the influenza seasonality in Taiwan was not clear during the four seasons under investigation. For example, the influenza A viruses peaked during the winters of 2001, 2002, and 2003. However, some isolated peaks were also found in the summer and fall (June to November) of 2001 and 2002. An unusual peak of influenza B also occurred in the summer of 2002 (June to August). Phylogenetic analysis shows that influenza A isolates from the same year were often grouped together. However, influenza B isolates from the year 2002 clustered into different groups, and the data indicate that both B/Victoria/2/87-like and B/Yamagata/16/88-like lineages of influenza B viruses were cocirculating. Sequence comparison of epidemic strains versus vaccine strains shows that many vaccine-like Taiwanese strains were circulating at least 2 years before the vaccine strains were introduced. No clear seasonality of influenza reports in Taiwan occurred in contrast to other more continental regions.     

Immunohistochemical, in situ hybridization, and ultrastructural localization of SARS-associated coronavirus in lung of a fatal case of severe acute respiratory syndrome in Taiwan

This article describes the pathological studies of fatal severe acute respiratory syndrome (SARS) in a 73-year-old man during an outbreak of SARS in Taiwan, 2003. Eight days before onset of symptoms, he visited a municipal hospital that was later identified as the epicenter of a large outbreak of SARS. On admission to National Taiwan University Hospital in Taipei, the patient experienced chest tightness, progressive dyspnea, and low-grade fever. His condition rapidly deteriorated with increasing respiratory difficulty, and he died 7 days after admission. The most prominent histopathologic finding was diffuse alveolar damage of the lung. Immunohistochemical and in situ hybridization assays demonstrated evidence of SARS-associated coronavirus (SARS-CoV) infection in various respiratory epithelial cells, predominantly type II pneumocytes, and in alveolar macrophages in the lung. Electron microscopic examination also revealed coronavirus particles in the pneumocytes, and their identity was confirmed as SARS-CoV by immunogold labeling electron microscopy. This report is the first to describe the cellular localization of SARS-CoV in human lung tissue by using a combination of immunohistochemistry, double-stain immunohistochemistry, in situ hybridization, electron microscopy, and immunogold labeling electron microscopy. These techniques represent valuable laboratory diagnostic modalities and provide insights into the pathogenesis of this emerging infection.     

Hepatitis B Virus Pre-S Gene Deletions and Pre-S Deleted Proteins: Clinical and Molecular Implications in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequent and fatal human cancers worldwide and its development and prognosis are intimately associated with chronic infection with hepatitis B virus (HBV). The identification of genetic mutations and molecular mechanisms that mediate HBV-induced tumorigenesis therefore holds promise for the development of potential biomarkers and targets for HCC prevention and therapy. The presence of HBV pre-S gene deletions in the blood and the expression of pre-S deleted proteins in the liver tissues of patients with chronic hepatitis B and HBV-related HCC have emerged as valuable biomarkers for higher incidence rates of HCC development and a higher risk of HCC recurrence after curative surgical resection, respectively. Moreover, pre-S deleted proteins are regarded as important oncoproteins that activate multiple signaling pathways to induce DNA damage and promote growth and proliferation in hepatocytes, leading to HCC development. The signaling molecules dysregulated by pre-S deleted proteins have also been validated as potential targets for the prevention of HCC development. In this review, we summarize the clinical and molecular implications of HBV pre-S gene deletions and pre-S deleted proteins in HCC development and recurrence and highlight their potential applications in HCC prevention and therapy.     

Preparing to prevent severe acute respiratory syndrome and other respiratory infections

Globalisation and its effect on human development has rendered an environment that is conducive for the rapid international spread of severe acute respiratory syndrome (SARS), and other new infectious diseases yet to emerge. After the unprecedented multi-country outbreak of avian influenza with human cases in the winter of 2003-2004, an influenza pandemic is a current threat. A critical review of problems and solutions encountered during the 2003-2004 SARS epidemics will serve as the basis for considering national preparedness steps that can be taken to facilitate the early detection of avian influenza, and a rapid response to an influenza pandemic should it occur.     

Approaches for Detection of Hepatitis B Virus Pre-S Gene Deletions and Pre-S Deleted Proteins and Their Application in Prediction of Higher Risk of Hepatocellular Carcinoma Development and Recurrence

Hepatocellular carcinoma (HCC) is among the most common and lethal human cancers worldwide and is closely associated with chronic hepatitis B virus (HBV) infection. Pre-S deleted proteins are naturally occurring mutant forms of HBV large surface proteins that are expressed by HBV surface genes harboring deletion mutations over the pre-S gene segments. It has been well demonstrated that HBV pre-S deleted proteins function as important oncoproteins, which promote malignant phenotypes of hepatocytes through the activation of multiple oncogenic signaling pathways and result in HCC formation. The oncogenic signaling pathways activated by pre-S deleted proteins have been verified as potential therapeutic targets for the prevention of HCC development. Moreover, the presence of pre-S gene deletions and the expression of pre-S deleted proteins in the blood and liver tissues of HBV-infected patients have been evaluated as valuable biomarkers for predicting a higher risk of HCC development and recurrence after curative surgical resection. Therefore, the precise detection of pre-S gene deletions and pre-S deleted proteins holds great promise as regards identifying the patients at higher risk of HCC development and recurrence, thus aiding in more timely and better treatments to improve their survival. This review summarizes the major approaches used for the detection of pre-S gene deletions and pre-S deleted proteins, including the approaches based on Sanger DNA sequencing, pre-S gene chips, next-generation sequencing and immunohistochemistry staining, and it highlights their important applications in the prediction of higher risks of HCC development and recurrence.     

Pathological features of betel quid-related oral epithelial lesions in taiwan with special emphasis on the tumor progression and human papillomavirus association

Betel quid (BQ) chewing has been a well-documented cause of oral epithelial lesions (OEL). Evolution from early hyperplastic lesions to the late or carcinomatous stage has been recognized. The pathobiological and molecular mechanism, however, remains to be elucidated. In this study, a total of 232 samples obtained from 153 cases of BQ-related OEL were retrospectively evaluated for the expression of p53 and bcl-2 in comparison with 26 cases of BQ-unrelated lesions (n = 29). The possible role of human papillomavirus (HPV) was also investigated. These BQ-related OELs included verrucous hyperplasia (VIH, n = 57, 24.6%), epithelial dysplasia (n = 23, 9.9%), verrucous carcinoma (VC, n = 5, 2.1%) and squamous cell carcinoma (SCC, n = 106, 45.7%). Fifty-four cases (35.3%) had multiple lesions. In comparison with the BQ-unrelated OELs, the characteristics of BQ-related OELs were a younger age, male predilection and multicentricity. In contrast to the tongue in BQ-unrelated OELs, the most common site for all types of BQ-related lesions was the buccal mucosa. Immunohistochemical studies of BQ-related lesions showed p53 staining in 30% of dysplasia and 38% of SCC, but a consistent absence in VH and VC. The cases with p53-positive SCC had a higher recurrence rate than p53-negative ones. Bcl-2 expression was negligible for all types of lesions. HPV-6/11 was detectable in 10% of dysplasia and 13% of SCC, but in neither VH nor VC. HPV-16/18, however, was consistently negative for all types of lesions. Our data suggest that p53, but not bcl-2, may play a role in tumor progression of BQ-related OELs, and that VH and VC are distinct and closely related histological lesions. The consistent absence of the malignant-type HPV in all BQ-related lesions suggests that HPV plays an insignificant role in the tumorigenesis of BQ-related oral cancers, although a cooperative role may exist between the benign-type HPV and BQ chewing.     

Neutralizing antibody response and SARS severity

Using the Taiwan nationwide laboratory-confirmed severe acute respiratory syndrome (SARS) database, we analyzed neutralizing antibody in relation to clinical outcomes. With a linear mixed model, neutralizing antibody titer was shown to peak between week 5 and week 8 after onset and to decline thereafter, with a half-life of 6.4 weeks. Patients with a longer illness showed a lower neutralizing antibody response than patients with a shorter illness duration (p = 0.008). When early responders were compared with most patients, who seroconverted on and after week 3 of illness, the small proportion (17.4%) of early responders (antibody detectable within 2 weeks) had a higher death rate (29.6% vs. 7.8%) (Fisher exact test, p = 0.004), had a shorter survival time of <2 weeks (Fisher exact test, p = 0.013), and were more likely to be > 60 years of age (Fisher exact test, p = 0.01). Our findings have implications for understanding the pathogenesis of SARS and for SARS vaccine research and development.     

Distribution and prognosis of WHO lymphoma subtypes in Taiwan reveals a low incidence of germinal-center derived tumors

To assess the distribution of lymphomas in Taiwan according to the WHO (World Health Organization) classification, 175 recently diagnosed cases of malignant lymphomas were studied and the clinicopathologic data were analyzed. B-cell lymphomas accounted for 57.1% of cases, T-cell lymphomas 38.9%, and Hodgkin's lymphoma 4%. Extranodal lymphomas predominated (55.4%). The most common subtype of B-cell lymphoma was diffuse large B-cell lymphoma (33.1%). All tumor types believed to be derived from germinal center (GC) B-cells including follicular lymphoma (4.6%), Burkitt lymphoma (1.7%), Hodgkin lymphoma (4.0%), and GC-like diffuse large B-cell lymphoma (as defined by combined expression of bcl-6 and CD10) were rather uncommon as compared to frequencies seen in series from Western countries. The common T-cell lymphomas included nasal and extranasal NK/T cell lymphoma (7.4%), mycosis fungoides (7.4%), and unspecified peripheral T-cell lymphoma (6.9%). Adult T-cell leukemia/lymphoma was very uncommon and accounts for only 0.6%. The proportional increase in T-cell lymphomas that were unrelated to type I human T-cell lymphotropic virus (HTLV-1) may be linked to differential Epstein-Barr virus (EBV) oncogenesis. The survival data revealed that mantle cell lymphoma, NK/T-cell lymphoma, unspecified peripheral T-cell lymphoma, and subcutaneous panniculitis-like T-cell lymphoma had an aggressive course. Our results confirm the utility of the WHO classification scheme for prognostic stratification and further highlight the distinctive distribution pattern of malignant lymphoma in Taiwan including the higher relative incidence of T cell lymphomas and the rarity of germinal center-derived B-cell tumors.     

Ground glass hepatocytes contain pre-S mutants and represent preneoplastic lesions in chronic hepatitis B virus infection

The discovery of "ground glass" hepatocytes (GGH) that contain hepatitis B virus (HBV) surface antigens by Hadziyannis and Popper in 1973 represents a historical landmark in the pathology of chronic HBV infection. Different types of GGH have been correlated to the expression patterns of surface/core antigens and the stages of virus replication. The original two types (designated types I & II) of GGH were found to contain specific pre-S mutants with deletions over either pre-S1 or pre-S2 regions, respectively. Type II GGH consistently harbor pre-S2 deletion mutants, which can escape from immune attack and grow preferentially to form clusters. Both types of pre-S mutants can induce endoplasmic reticulum (ER) stress and oxidative DNA damage. The pre-S2 mutants, albeit inducing a weaker level of ER stress signals, could additionally initiate ER stress-independent retinoblastoma/adenovirus E2 promoter binding factor/cyclin A signaling through their interaction with c-Jun activation domain binding protein 1 to degrade p27, illustrating the growth advantage of type II GGH. The combined effects of genomic instability and the proliferation of hepatocytes harboring pre-S mutants could potentially lead to hepatocarcinogenesis over the decades of chronic HBV infection. The presence of pre-S mutants in sera was reported to carry a high risk of developing hepatocellular carcinoma (HCC). Furthermore, transgenic mice harboring pre-S2 mutant plasmids have been shown to develop a dysplastic change of hepatocytes and HCC. Therefore, in addition to being a histological marker of chronic HBV infection, GGH, particularly type II GGH, may represent the preneoplastic lesions of HBV-related HCC.