Yu-Jiun Chan

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

ABSTRACT 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.

DC-SIGN mediates avian H5N1 influenza virus infection in cis and in trans

Abstract DC-SIGN, a C-type lectin receptor expressed in dendritic cells (DCs), has been identified as a receptor for human immunodeficiency virus type 1, hepatitis C virus, Ebola virus, cytomegalovirus, dengue virus, and the SARS coronavirus. We used H5N1 pseudotyped and reverse-genetics (RG) virus particles to study their ability to bind with DC-SIGN. Electronic microscopy and functional assay results indicate that pseudotyped viruses containing both HA and NA proteins express hemagglutination and are capable of infecting cells expressing α-2,3-linked sialic acid receptors. Results from a capture assay show that DC-SIGN-expressing cells (including B-THP-1/DC-SIGN and T-THP-1/DC-SIGN) and peripheral blood dendritic cells are capable of transferring H5N1 pseudotyped and RG virus particles to target cells; this action can be blocked by anti-DC-SIGN monoclonal antibodies. In summary, (a) DC-SIGN acts as a capture or attachment molecule for avian H5N1 virus, and (b) DC-SIGN mediates infections in cis and in trans.

Seroprevalence of Antibodies to Pandemic (H1N1) 2009 Influenza Virus Among Hospital Staff in a Medical Center in Taiwan

Background: The pandemic (H1N1) 2009 influenza emerged in April 2009 and spread rapidly and broadly all over the world. In addition to specific antiviral agents, massive vaccination is thought to be the most effective way of controlling the transmission. To understand the prevaccination status of certain risk groups, this study compared the baseline sero‐prevalence of antibodies to the pandemic (H1N1) 2009 influenza virus among hospital staff with different contact risks and that of the general population. Methods: A total of 295 serum samples from hospital staff and 244 control serum samples from people who came for physical check‐up (control group) were collected between October 2009 and November 2009 before the massive vaccination campaign. The hospital staff was divided into first‐line risk personnel (group 1) and second‐line risk personnel (group 2) according to their potential contact risks. Hemagglutination‐inhibition (HI) tests were conducted to determine the individual serological status. The seropositive rate (SPR, defined as the proportion with HI titer ≥ 1:40) of antibodies to H1N1 influenza virus and its geometric mean titer (GMT) were calculated and compared among the different groups. Results: The mean ages and sex ratio (% male) of the hospital staff and control groups were 36.9 ± 10.6 years and 52.0 ± 12.6 years, and 24.4% and 57.6%, respectively. The SPR of the antibodies to H1N1 influenza virus of the hospital staff was significantly higher than that of the control group (20.0% vs. 2.9%, p < 0.001). Furthermore, the SPR antibodies to H1N1 influenza virus of group 1 were significantly higher than that of group 2 (30.8% vs. 12.6%, p < 0.001). However, the GMT of antibodies to H1N1 influenza virus of the hospital staff was not significantly different from that of the control group (p = 0.925). Conclusion: The SPR of antibodies against the pandemic (H1N1) 2009 virus in the hospital staff was higher than that in the general population, reflecting a higher contact risk. Prevaccination surveillance of the immune status of different risk groups may help to prioritize which groups should be vaccinated first.

Clinical and microbiological analysis of Elizabethkingia meningoseptica bacteremia in adult patients in Taiwan.

A limited number of reports have documented bacteremia caused by Elizabethkingia meningoseptica (Chryseobacterium meningosepticum) in adults. Most cases have occurred in Taiwan. This study investigated the clinical features and risk factors for mortality from E. meningoseptica bacteremia and the antimicrobial susceptibilities of the isolates. Patients with E. meningoseptica bacteremia were retrospectively analyzed at a medical center/teaching hospital in northern Taiwan over a 3-y period. We analyzed clinical features and outcomes of patients and antimicrobial susceptibilities and pulsed-field gel electrophoresis (PFGE) results of the isolates. 28 patients had nosocomial bacteremia and 4 patients had healthcare associated bacteremia. The isolates exhibited variable susceptibilities to levofloxacin, ciprofloxacin, piperacillin-tazobactam, tigecycline, and trimethoprim-sulfamethoxazole. PFGE demonstrated that most isolates were epidemiologically unrelated. The 28-d mortality rate was 41%. Multivariate analysis indicated that shock and use of inappropriate antibiotics were independent risk factors for mortality. In conclusion, nosocomial bloodstream infection due to E. meningoseptica is an increasing problem in Taiwan. Our study indicates that patients with E. meningoseptica bacteremia face poor prognoses, with shock and use of inappropriate antibiotics as the main risk factors for mortality. Further clinical study is needed to establish the optimal therapy for E. meningoseptica bacteremia.

Human cytomegalovirus preferentially infects the neoplastic epithelium of colorectal cancer: a quantitative and histological analysis.

BACKGROUND It has long been suggested that human cytomegalovirus (HCMV) might be involved in human oncogenesis. However, whether HCMV was associated with colorectal cancer (CRC) was still controversial. OBJECTIVE To clarify whether HCMV specifically infects the tumorous tissue of CRC. STUDY DESIGN Paired tumor and adjacent non-neoplastic CRC specimens were collected from 163 patients. HCMV DNA was detected and quantified through PCR and quantitative real-time PCR. Virus location was determined by in situ hybridization (ISH) of formalin-fixed paraffin-embedded tissue sections with an HCMV-specific probe. RESULTS By PCR, HCMV DNA was detected in 42.3% (69/163) of the tumor specimens, while only 5.6%(14/163) samples of adjacent non-neoplastic tissue were positive for HCMV (p<0.0001). Quantitative real-time PCR in 54 sample pairs revealed significantly higher viral copies in the tumor specimens than the adjacent non-neoplastic tissue specimens (p<0.001). By ISH, the nucleic acids of HCMV were detected in the cytoplasm of neoplastic epithelium. No hybridization was detected in the inflammatory infiltrates, submucosa, or other stromal tissues. CONCLUSIONS HCMV preferentially infects the tumor epithelium of CRC. How the virus subsists in and interacts with the microenvironment of tumor epithelium of CRC should be studied.

Overview of Ebola virus disease in 2014

Abstract In late December 2013, a deadly infectious epidemic, Ebola virus disease (EVD), emerged from West Africa and resulted in a formidable outbreak in areas including Guinea, Liberia, Sierra Leone and Nigeria. EVD is a zoonotic disease with a high mortality rate. Person‐to‐person transmission occurs through blood or body fluid exposure, which can jeopardize first‐line healthcare workers if there is a lack of stringent infection control or no proper personal protective equipment available. Currently, there is no standard treatment for EVD. To promptly identify patients and prevent further spreading, physicians should be aware of travel or contact history for patients with constitutional symptoms.

Generating and characterizing monoclonal and polyclonal antibodies against avian H5N1 hemagglutinin protein.

Accurate and timely diagnoses are central to H5N1 infection control. Here we describe the cloning and expression of the HA1 protein of the A/Vietnam/1203/04 strain in a bacterial system to generate mono-/polyclonal antibodies. All of the eight generated monoclonal antibodies recognized the same linear epitope on the top globular region of the HA structure -- a highly conserved epitope among all circulating H5N1 clades identified by amino acid alignment. Results from immunofluorescence staining and Western blotting indicate that all monoclonal antibodies interacted with a denatured form of HA proteins, while the resultant polyclonal antibodies recognized both denatured and native HA proteins on H5N1 reverse-genetics (RG) viruses. Results from flow cytometry and microneutralization assays indicate that the polyclonal antibodies blocked viral binding and neutralized H5N1-RG viruses. Our results may prove useful to establishing future H5N1 mono-and polyclonal antibodies, and perhaps contribute to the development of an alternative H5N1 vaccine.

Epidemiological and genetic correlates of severe acute respiratory syndrome coronavirus infection in the hospital with the highest nosocomial infection rate in Taiwan in 2003.

ABSTRACT Taiwan experienced a series of outbreaks of nosocomial severe acute respiratory syndrome (SARS) infections in 2003. Two months after the final outbreak, we recruited 658 employees from the hospital that suffered the first and most severe SARS infections to help us investigate epidemiological and genetic factors associated with the SARS coronavirus (SARS-CoV). SARS-CoV infections were detected by using enzyme immunoassays and confirmed by a combination of Western blot assays, neutralizing antibody tests, and commercial SARS tests. Risk factors were analyzed via questionnaire responses and sequence-specific oligonucleotide probes of human leukocyte antigen (HLA) alleles. Our results indicate that 3% (20/658) of the study participants were seropositive, with one female nurse identified as a subclinical case. Identified SARS-CoV infection risk factors include working in the same building as the hospitals emergency room and infection ward, providing direct care to SARS patients, and carrying a Cw*0801 HLA allele. The odds ratio for contracting a SARS-CoV infection among persons with either a homozygous or a heterozygous Cw*0801 genotype was 4.4 (95% confidence interval, 1.5 to 12.9; P = 0.007).

Associated clinical characteristics of patients with candidemia among different Candida species

BACKGROUND The rising incidence of non-albicans Candida (NAC) infection has been associated with a potentially adverse outcome for patients with candidemia. However, categorizing various species causing candidemia into a single NAC group might lead to inappropriate conclusions due to heterogeneity in species. Thus we examined the associated factors among patients with candidemia caused by different species. METHODS This retrospective study was conducted at a tertiary medical center in Taiwan from 2006 to 2009. Mortality rate, demographic and clinical characteristics, albumin levels, and severity scores of acute illness of patients at the onset of candidemia were analyzed. RESULTS A total of 447 episodes among 418 patients were included for analysis. The overall 30-day crude mortality was 48.2%, with no significant difference between C. albicans and NAC candidemia, but apparently C. parapsilosis candidemia was associated with a lower mortality rate. Time to positivity for yeast was significantly different between species. Compared with infection involving C. albicans, more frequent use of total parenteral nutrition, lower Sequential Organ Failure Assessment score and higher albumin levels were observed for C. parapsilosis candidemia. CONCLUSION Identifying associated factors for each species may be a more effective approach than single NAC grouping. Time to positivity may be a hint for treatment guidance in candidemia. More frequent use of total parenteral nutrition and less virulent nature were noted for C. parapsilosis candidemia.

Influenza A virus in Taiwan, 1980–2006: Phylogenetic and antigenic characteristics of the hemagglutinin gene

Limited amount of information is available in Taiwan on the genetic or antigenic characteristics of influenza A virus prior to the establishment of a Taiwan surveillance network in 2000. Isolates of H1N1 and H3N2 viruses in Taiwan between 1980 and 2006 were studied, and part of the hemagglutinin gene was analyzed due to its importance in terms of viral infection and antibody neutralization. Results from a phylogenetic analysis indicate continuous evolutionary topology in H3N2 isolates, and two distinct H1N1 lineages. Many genetic relationships between vaccine strains and epidemic isolates appearing in Taiwan before other global locations were also observed and recorded in addition to a gradual increase in the number of N‐linked glycosylation sites on partial HA1 proteins since 1980. The results from pairwise comparisons of HA1 nucleotide and deduced amino acid sequences indicate shared identities within groups organized according to their bootstrap and P‐values of approximately 95.5–100% and 95.7–100% in H1N1 and 94.5–100% and 93.2–100% in H3N2 viruses, respectively. Comparisons of amino acid substitutions in the five antigenic regions reveal highly non‐synonymous changes occurring in the Sb region of H1N1 and in the B region of H3N2. The results of an antigenic analysis using a hemagglutinin inhibition (HI) test indicate the presence of some epidemic strains 1–2 years earlier in Taiwan than in other parts of the world, as well as higher vaccine mismatch rates. This information supports the need for continuous surveillance of emerging influenza viruses in Taiwan, which will be useful for making global vaccine decisions. J. Med. Virol. 81:1457–1470, 2009.