The emergence and successful elimination of SARS-CoV-2 dominant strains with increasing epidemic potential in Taiwan's 2021 outbreak.

Taiwan's experience with severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 guided its development of strategies to defend against SARS-CoV-2 in 2020, which enabled the successful control of Coronavirus disease 2019 (COVID-19) cases from 2020 through March 2021. However, in late-April 2021, the imported Alpha variant began to cause COVID-19 outbreaks at an exceptional rate in Taiwan. In this study, we aimed to determine what epidemiological conditions enabled the SARS-CoV-2 Alpha variant strains to become dominant and decline later during a surge in the outbreak. In conjunction with contact-tracing investigations, we used our bioinformatics software, CoVConvert and IniCoV, to analyze whole-genome sequences of 101 Taiwan Alpha strains. Univariate and multivariable regression analyses revealed the epidemiological factors associated with viral dominance. Univariate analysis showed the dominant Alpha strains were preferentially selected in the surge's epicenter (p = 0.0024) through intensive human-to-human contact and maintained their dominance for 1.5 months until the Zero-COVID Policy was implemented. Multivariable regression found that the epidemic periods (p = 0.007) and epicenter (p = 0.001) were two significant factors associated with the dominant virus strains spread in the community. These dominant virus strains emerged at the outbreak's epicenter with frequent human-to-human contact and low vaccination coverage. The Level 3 Restrictions and Zero-COVID policy successfully controlled the outbreak in the community without city lockdowns. Our integrated method can identify the epidemiological conditions for emerging dominant virus with increasing epidemiological potential and support decision makers in rapidly containing outbreaks using public health measures that target fast-spreading virus strains.

Inhibition of HIV-1 Tat-mediated transcription by a coumarin derivative, BPRHIV001, through the Akt pathway.

The human immunodeficiency virus type 1 (HIV-1)-encoded RNA-binding protein Tat is known to play an essential role in viral gene expression. In the search for novel compounds to inhibit Tat transactivity, one coumarin derivative, BPRHIV001, was identified, with a 50% effective concentration (EC(50)) against HIV-1 at 1.3 nM. BPRHIV001 is likely to exert its effects at the stage after initiation of RNAPII elongation since Tat protein expression and the assembly of the Tat/P-TEFb complex remained unchanged. Next, a reduction of the p300 protein level, known to modulate Tat function through acetylation, was observed upon BPRHIV001 treatment, while the p300 mRNA level was unaffected. A concordant reduction of phosphorylated Akt, which was shown to be closely related to p300 stability, was observed in the presence of BPRHIV001 and was accompanied by a decrease of phosphorylated PDPK1, a well-known Akt activator. Furthermore, the docking analysis revealed that the reduced PDPK1 phosphorylation likely resulted from the allosteric effect of interaction between BPRHIV001 and PDPK1. With strong synergistic effects with current reverse transcriptase inhibitors, BPRHIV001 has the potential to become a promising lead compound for the development of a novel therapeutic agent against HIV-1 infection.

Lack of resistance-associated mutations in UL54 and UL97 genes of circulating cytomegalovirus strains isolated in a medical center in Taiwan.

Human cytomegalovirus (HCMV) is a large DNA virus and a member of the betaherpesvirus family. HCMV infection is extremely common in human populations and can cause severe diseases in immunocompromised hosts. Ganciclovir is the most widely used antiviral drug for cytomegalovirus infection and works by blocking the amplification of HCMV. HCMV strains resistant to ganciclovir have been detected in recent decades and mainly result from mutations in UL97 (protein kinase) and UL54 (DNA polymerase) genes. In order to understand the prevalence of resistance of HCMV in Taiwan, we studied 40 clinical isolates to detect the mutations of UL97 and UL54 that might be related to resistance. The results showed that no mutation known to cause ganciclovir resistance was detected in any strain, but some polymorphisms (N685S, A688V, A885T, N898D in UL54; D605E in UL97) were frequently observed. Our results suggest that resistant HCMV strains are not prevalent in Taiwan.

Viral load and clinical features in children infected with seasonal influenza B in 2006/2007.

BACKGROUND/PURPOSE: In influenza B infection, viral load is believed to be related to the severity of clinical illness. The correlation between viral load and symptoms is not known. We conducted a study to assess the relationship between virus load and clinical features in children infected with influenza B, in the hope that clinical features could be used as surrogate markers of viral load to guide treatment. METHODS: Between December 2006 and February 2007, 228 patients with fever and respiratory symptoms were prospectively enrolled in our tertiary hospital-based study. Real-time reverse transcription polymerase chain reaction (RT-PCR) was performed to determine viral load. RESULTS: Real-time RT-PCR was positive for influenza B in 76 patients. Using virus culture as the gold standard, the sensitivity and specificity were 95% and 87%, respectively. Influenza culture positive rate significantly correlated with viral load (p = 0.03). The median copy number of influenza B virus in the 76 RT-PCR positive patients was 9735 copies/ml (range 4.8×10¹-2.0×106 copies/ml). Samples obtained later in the clinical course tended to have lower viral load (p = 0.7), while patient age (p = 0.72) and fever duration (p = 0.96) positively related to viral load. In patients >3 years of age, myalgia was related to statistically lower viral loads (14300 vs. 1180; p = 0.025). Patients with chills tended to have higher viral loads (72450 vs. 7640; p = 0.1). Patients with abdominal pain tended to have lower viral loads (1998 vs. 12550; p = 0.06). CONCLUSION: Culture rate positively correlated with viral load. Patients with myalgia had a lower viral load.

Risk factors of severe novel influenza A (H1N1) infections in hospitalized children.

BACKGROUND/PURPOSE: Data on hospitalized novel influenza A (H1N1) infected children are limited and urgently in demand. We conducted a clinical study to identify clinical features and risk factors associated with severe novel H1N1 infections of children in Taiwan. METHODS: From July 24, 2009 to December 4, 2009, data from 61 hospitalized children infected with 2009 novel H1N1 were collected. Demographics, underlying medical conditions, clinical data, receipt of antiviral therapy, need for intensive care and outcome were analyzed to identify clinical features and risk factors of severe infections. RESULTS: Of the 61 inpatients, the male to female ratio was 41 to 20 and the most common age group was between 6 and 12 years (36%). Almost all (98%) patients had fever, 53 (87%) patients received oseltamivir treatment and 51% of them received oseltamivir within 48 hours. Fourteen (23%) needed intensive care and 3 died. Obesity (a Body Mass Index ≥ 25 kg/m(2) in children ≥ 2 years of age, or a body weight ≥ the 95(th) percentile in children <2 years of age), dyspnea, C-reactive protein (CRP) > 3 mg/dL, pleural effusion, and delayed antiviral therapy were significantly associated with the need for intensive care and/or death. CONCLUSION: Obesity, dyspnea, CRP > 3 mg/dL, pleural effusion, and delayed antiviral therapy are significantly associated with severe novel H1N1 infections in children.

Human TLR3 recognizes dengue virus and modulates viral replication in vitro.

The elicitation of large amount inflammatory cytokine in serum has been developed as the cause of the plasma leakage in dengue fever (DF)/dengue haemorrhagic fever (DHF) infection. Virus recognition in innate immunity is the key. The Toll-like receptors (TLRs) play an important role in pathogen recognition towards cytokine induction among several viruses; however, the role of TLRs on innate immune recognition against DENV remains unclear. This study aims at the interaction between dengue virus (DENV) and human TLRs at the incipient stage of infection in vitro. Our experiment reveals that stably expression of TLR3, 7, 8 on HEK293 enables IL-8 secretion after DENV recognition. By the model of human monocytic cells U937, we demonstrated the trigger of IL-8 after viral recognition of human monocytic cell is primary through TLR3 following endosomal acidification. Silencing of TLR3 in U937 cells significantly blocks the DENV-induced IL-8 production. Besides, the interaction is further corroborated by colocalization of TLR3 and DENV RNA upon DENV internalization. Furthermore, in this study we found the expression of TLR3 can mediate strong IFN-alpha/beta release and inhibit DENV viral replication significantly, thus limit the cytopathic effect.

Association of single-nucleotide polymorphism 3 and c.553G>T of APOA5 with hypertriglyceridemia after treatment with highly active antiretroviral therapy containing protease inhibitors in hiv-infected individuals in Taiwan.

We investigated the relationship between hypertriglyceridemia and the single-nucleotide polymorphisms (SNPs) on APOA5 in human immunodeficiency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART) in Taiwan. Receipt of protease inhibitor-based HAART, high baseline triglyceride levels, and carriage of APOA5 SNP3 or c.553G>T variants or APOA5 SNP1T/SNP2G/SNP3C/c.553T haplotype were statistically significantly associated with development of extreme hypertriglyceridemia (triglyceride level, >500 mg/dL).

Antibodies to envelope glycoprotein of dengue virus during the natural course of infection are predominantly cross-reactive and recognize epitopes containing highly conserved residues at the fusion loop of domain II.

The antibody response to the envelope (E) glycoprotein of dengue virus (DENV) is known to play a critical role in both protection from and enhancement of disease, especially after primary infection. However, the relative amounts of homologous and heterologous anti-E antibodies and their epitopes remain unclear. In this study, we examined the antibody responses to E protein as well as to precursor membrane (PrM), capsid, and nonstructural protein 1 (NS1) of four serotypes of DENV by Western blot analysis of DENV serotype 2-infected patients with different disease severity and immune status during an outbreak in southern Taiwan in 2002. Based on the early-convalescent-phase sera tested, the rates of antibody responses to PrM and NS1 proteins were significantly higher in patients with secondary infection than in those with primary infection. A blocking experiment and neutralization assay showed that more than 90% of anti-E antibodies after primary infection were cross-reactive and nonneutralizing against heterologous serotypes and that only a minor proportion were type specific, which may account for the type-specific neutralization activity. Moreover, the E-binding activity in sera of 10 patients with primary infection was greatly reduced by amino acid replacements of three fusion loop residues, tryptophan at position 101, leucine at position 107, and phenylalanine at position 108, but not by replacements of those outside the fusion loop of domain II, suggesting that the predominantly cross-reactive anti-E antibodies recognized epitopes involving the highly conserved residues at the fusion loop of domain II. These findings have implications for our understanding of the pathogenesis of dengue and for the future design of subunit vaccine against DENV as well.

Determination of human rotavirus VP6 genogroups I and II by reverse transcription-PCR.

Based on nucleotide sequence and phylogenetic analysis of the partial VP6 genes, group A rotaviruses can be mainly differentiated into two genogroups. In this study, a method employing reverse transcription-PCR (RT-PCR) and degenerate primers was established to assign the VP6 genogroup. VP6 genogroup I and genogroup II could be determined according to the sizes of the amplicons: 380 and 780 bp, respectively. The VP6 genogroup of human reference strains of G1 to G4 and G9 types and RotaTeq vaccine strains could be properly assigned by RT-PCR. Eighty rotavirus-positive fecal samples were subjected to enzyme-linked immunosorbent assay (ELISA), RT-PCR, and sequencing of the partial VP6 gene for subgroup and genogroup determination. The results correlated well among these three methods, except for seven samples whose subgroups could not be determined by ELISA. VP6 genogroups of another 150 rotavirus strains recovered between 1981 and 2005 were determined by RT-PCR and sequencing, and the same results were obtained by these two methods. Furthermore, an additional 524 rotavirus-positive fecal samples were tested by RT-PCR, and the VP6 genogroups could be easily determined. The RT-PCR assay developed here provided a reliable and convenient method for assigning the VP6 genogroups of human rotaviruses with a wide range of genetic variation.

Trends of antiretroviral drug resistance in treatment-naive patients with human immunodeficiency virus type 1 infection in Taiwan.

OBJECTIVES: To determine the prevalence and trends of antiretroviral drug resistance among HIV-1-infected Taiwanese patients who have been provided with free-of-charge antiretroviral therapy (ART) since 1990. METHODS: Blood samples collected from 786 HIV-1-infected patients from 1999 to 2006 were subjected to genotypic resistance assay. Antiretroviral resistance mutations were identified in accordance with the antiretroviral resistance mutation list of the International AIDS Society-USA Consensus Guidelines. Trends of resistance were studied in patients enrolled in two periods: before (period 1, January 1999 to December 2003) and after (period 2, January 2004 to December 2006) the CRF07_BC outbreak among injection drug users (IDUs). RESULTS: The frequency of HIV-1 isolates harbouring one or more primary mutations associated with antiretroviral resistance to reverse transcriptase inhibitors or protease inhibitors increased significantly from 6.6% in period 1 to 12.7% in period 2 (P = 0.003). A significant increase in prevalence of antiretroviral drug resistance was observed among men who have sex with men and patients infected with HIV subtype B. In multivariate analysis, hepatitis C virus (HCV) exposure, which exhibited collinearity with injection drug use and infection with CRF07_BC, represented a lower risk for infection with resistant viruses. CONCLUSIONS: Our findings suggest that the prevalence of antiretroviral resistance has increased in Taiwan over the past 8 years after the introduction of combination ART. IDUs who were HCV-seropositive and infected with CRF07_BC were at lower risk for infection with antiretroviral-resistant viruses.

Anti-HSV activity of digitoxin and its possible mechanisms.

Herpes simplex virus type 1 (HSV-1) can establish latent infection in the nervous system and usually leads to life-threatening diseases in immunocompromised individuals upon reactivation. Treatment with conventional nucleoside analogue such as acyclovir is effective in most cases, but drug-resistance may arise due to prolonged treatment in immunocompromised individuals. In this study, we identified an in-use medication, digitoxin, which actively inhibited HSV-1 replication with a 50% effective concentration (EC(50)) of 0.05 microM. The 50% cytotoxicity concentration (CC(50)) of digitoxin is 10.66 microM and the derived selective index is 213. Several structural analogues of digitoxin such as digoxin, ouabain octahydrate and G-strophanthin also showed anti-HSV activity. The inhibitory effects of digitoxin are likely to be introduced at the early stage of HSV-1 replication and the virus release stage. The observation that digitoxin can inhibit acyclovir-resistant viruses further implicates that digitoxin represents a novel drug class with distinct antiviral mechanisms from traditional drugs.

Ribavirin for respiratory syncytial virus bronchiolitis reduced the risk of asthma and allergen sensitization.

Respiratory syncytial virus (RSV) bronchiolitis in early life is a risk factor for later development of asthma and atopy. Ribavirin is the only effective drug currently available against acute RSV bronchiolitis. However, the long-term effects of ribavirin remain unclear. We investigated a cohort of children hospitalized with RSV bronchiolitis from when they were under 2 yr old until they reached a mean age of 6.2 yr. In total, we enrolled 175 children in this study. Both the group treated with ribavirin and the group not treated with ribavirin included high-risk young children with congenital heart disease or chronic lung disease. Their respective age-matched controls, that we labeled groups A and B, both without ribavirin treatment, consisted of previously healthy subjects. Wheezing was either verified by physicians or estimated by a questionnaire. Allergen sensitization was judged by serum allergen-specific IgE levels. The cumulative incidence of physician-diagnosed asthma or recurrent wheezing in the ribavirin group (15%) was significantly lower than its incidence in the non-ribavirin-treated group (34%, p = 0.049), and in the control A group (43%, p = 0.005). Allergen sensitization was also least frequent in the ribavirin group. Ribavirin therapy was an independent factor in reducing the risk of developing asthma, asthma/recurrent wheezing, and sensitization to D. pteronyssinus/D. farinae. The long-term value of ribavirin for acute RSV bronchiolitis and its underlying mechanisms deserves further research.

Clinical manifestations of human coronavirus NL63 infection in children in Taiwan.

Human coronavirus NL63 (HCoV-NL63) is a global respiratory tract pathogen; however, the epidemiology of this virus in subtropical area is not well known. To evaluate the epidemics and disease spectrum of HCoV-NL63 infection in children in Taiwan, we prospectively screened children admitted to the hospital with respiratory tract infection from May 2004 to April 2005. Every enrolled child had a nasopharyngeal aspirate (NPA) sample taken. Quantitative RT-PCR was used to detect 1b gene of HCoV-NL63. A total of 539 NPAs were collected. Seven (1.3%) were positive for HCoV-NL63. All cases were boys younger than 3 years of age and most cases occurred in autumn. Co-infection with other pathogens was observed in three cases. The most common symptoms/signs of HCoV-NL63 infection were cough, fever, and inspiratory stridor. HCoV-NL63 was the most common pathogen (14.7%) in children with croup and was the cause of three cases of croup in October. The odds ratio of croup in children infected with HCoV-NL63 was 43.4 (95% CI 8.1 approximately 233.1). In conclusion, HCoV-NL63 is an important respiratory tract pathogen as the main cause in children admitted to the hospital in Taiwan.

Astrovirus gastroenteritis in children in Taipei.

BACKGROUND/PURPOSE: A prospective study was initiated to study astroviral infections in Taiwan. METHODS: A total of 415 stool samples were collected and assayed for astrovirus antigen using an enzyme immunoassay. RESULTS: Twelve (2.9%) stool samples from 12 patients were positive for astrovirus antigen. Most patients (8/12) had watery diarrhea which lasted for 2-6 days. The majority of patients recovered without specific treatment, except for two patients who were treated with antibiotics for possible bacterial infections. One patient developed chronic diarrhea and two episodes were nosocomially acquired. A clustering in the autumn and winter, with a peak in December (5/12), was noted. Growth on Caco-2 cells was performed for four specimens with positive astroviral RT-PCR results, and a characteristic cytopathic effect was observed after 4 days. Astroviral RNA was detected in six stool samples using RT-PCR. Five of six strains were serotype 1 and one strain was serotype 3. Sequence homology among the six strains was between 80.5% and 100%. A higher degree of homology (89.9-100%) was noted in the five strains of serotype 1. A phylogenetic study demonstrated two clusters in our strains and Oxford reference strain types 1 and 2. CONCLUSION: Our study results provide further information about the prevalence and span of clinical spectra associated with astroviral infections in Taiwan. The current study showed that infection with astroviruses may be an important cause of gastroenteritis, as well as respiratory symptoms, in infants and children in Taipei.

Inter- and intra-host sequence diversity reveal the emergence of viral variants during an overwintering epidemic caused by dengue virus serotype 2 in southern Taiwan.

Purifying selection during dengue viral infection has been suggested as the driving force of viral evolution and the higher complexity of the intra-host quasi-species is thought to offer an adaptive advantage for arboviruses as they cycle between arthropod and vertebrate hosts. However, very few studies have been performed to investigate the viral genetic changes within (intra-host) and between (inter-host) humans in a spatio-temporal scale. Viruses of different serotypes from various countries imported to Taiwan cause annual outbreaks. During 2001-2003, two consecutive outbreaks were caused by dengue virus serotype 2 (DENV-2) and resulted in a larger-scale epidemic with more severe dengue cases in the following year. Phylogenetic analyses showed that the viruses from both events were similar and related to the 2001 DENV-2 isolate from the Philippines. We comprehensively analyzed viral sequences from representative dengue patients and identified three consensus genetic variants, group Ia, Ib and II, with different spatio-temporal population dynamics. The phylodynamic analysis suggested group Ib variants, characterized by lower genetic diversity, transmission rate, and intra-host variant numbers, might play the role of maintenance variants. The residential locations among the patients infected by group Ib variants were in the outer rim of case clusters throughout the 2001-2003 period whereas group Ia and II variants were located in the centers of case clusters, suggesting that group Ib viruses might serve as "sheltered overwintering" variants in an undefined ecological niche. Further deep sequencing of the viral envelope (E) gene directly from individual patient serum samples confirmed the emergence of variants belonging to three quasi-species (group Ia, Ib, and II) and the ancestral role of the viral variants in the latter phase of the 2001 outbreak contributed to the later, larger-scale epidemic beginning in 2002. These findings enhanced our understanding of increasing epidemic severity over time in the same epidemic area. It also highlights the importance of combining phylodynamic and deep sequencing analysis as surveillance tools for detecting dynamic changes in viral variants, particularly searching for and monitoring any specific viral subpopulation. Such subpopulations might have selection advantages in both fitness and transmissibility leading to increased epidemic severity.

Epidemiology of respiratory syncytial virus infection in northern Taiwan, 2001-2005 -- seasonality, clinical characteristics, and disease burden.

BACKGROUND AND PURPOSE: Respiratory syncytial virus (RSV) is an important pathogen in children less than 2 years old. However, there is limited epidemiological data about RSV infection in Taiwan. This study aimed to investigate the clinical, epidemiological, virological, and economical aspects of RSV infections in Taiwan. METHODS: We collected data of children with positive RSV respiratory specimens at the Laboratory of Virology, National Taiwan University Hospital, between January 2001 and December 2005. Medical charts were reviewed retrospectively. RESULTS: 892 children in whom acute bronchiolitis was the predominant diagnosis (60.7%) were enrolled. Compared with those without underlying disease (n = 630), children with underlying disease (n = 262) were older (11 vs 9 months), required longer oxygen therapies (7 vs 4 days), were more likely to have lower respiratory tract involvement (96.2% vs 92.3%) and intensive care unit stays (49.0% vs 9.4%), endotracheal intubations (21.0% vs 2.0%), ribavirin use (35.0% vs 1.4%), and had higher medical costs (US$ 1250 vs 688), and nosocomial infection (24.8% vs 1.0%). Compared with those without endotracheal intubation (n = 824), cases requiring endotracheal intubation (n = 68) had higher rates of underlying diseases (80.9% vs 25.1%), especially congenital heart diseases (45.6% vs 8.1%), chronic lung disease (13.2% vs 3.2%) and neurological disorders (17.6% vs 3.5%). There was a biennial pattern with peaks in the spring and fall. Medical cost was estimated to be US$ 250,000 annually in our hospital. CONCLUSION: In children with underlying diseases, RSV infection is associated with significant morbidity, and even mortality. Nosocomial infections appear to be an important cause of RSV transmission. The seasonality of RSV infections in Taiwan showed a biennial pattern with peaks in spring and fall.

Hand, foot and mouth disease complicated with central nervous system involvement in Taiwan in 1980-1981.

Sixteen cases from the 1980-1981 Taiwan outbreak of hand, foot and mouth disease (HFMD) associated with central nervous system involvement were identified: nine had polio-like syndrome, four had encephalitis or encephalomyelitis, one had cerebellitis, and two had aseptic meningitis. They all had fever, five (31%) had documented myoclonic jerk, and 15 (93%) had HFMD. Their mean blood leukocyte count was 12,490/microL, and five (31%) had leukocytosis (> 15,000/microL); mean cerebrospinal fluid (CSF) leukocyte count was 156/microL, CSF protein was 57 mg/dL and CSF glucose was 57 mg/dL. Two patients with HFMD plus encephalitis died within 1 day of hospitalization, and one of them had acute cardiopulmonary failure mimicking myocarditis. Twenty years later, at least one male patient had sequelae of polio-like syndrome and was therefore exempted from military service. Clinical severity was comparable to the 1998 EV71 epidemic.

Detection of human metapneumovirus in hospitalized children with acute respiratory tract infection using real-time RT-PCR in a hospital in northern Taiwan.

BACKGROUND/PURPOSE: Human metapneumovirus (hMPV) is a newly discovered respiratory pathogen. This prospective hospital-based study investigated the clinical role and features of hMPV in Taiwan. METHODS: Respiratory specimens collected from hospitalized children with acute respiratory tract infection between September 1, 2003 and April 10, 2005 were screened for metapneumovirus using real-time reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: During the study period, 930 specimens were obtained from 926 hospitalized children. After exclusion of 200 cases due to lack of clinical evidence of airway infection or diseases with known etiology, 726 were included in the analysis. Among these, 33 children had a positive result for hMPV infection. The majority of these patients were admitted during spring and early summer. Twenty-one (63.6%) were younger than 2 years of age. hMPV accounted for 13.3% of respiratory infections occurring between the ages of 18 and 24 months and was as common a respiratory pathogen as respiratory syncytial virus (RSV) in that age group. The 11 patients (33.3%) with underlying diseases had a similar disease course to those without underlying diseases. A co-pathogen was found in 11 patients (33.3%). Infected children between 2 and 5 years of age had significantly higher titers of hMPV in their respiratory specimens (103.88 copies/microL) than children younger than 2 years (102.26 copies/microL) (p = 0.013) and children older than 5 years (102.25 copies/microL) (p = 0.005). hMPV positive cases were significantly older than those with RSV infection (p = 0.002) and had a shorter duration of hospitalization (p = 0.001), fewer days of oxygen use (p = 0.001) and higher levels of C-reactive protein (p = 0.004). CONCLUSION: Metapneumovirus circulates in children in northern Taiwan during spring and early summer. hMPV was the most common respiratory pathogen in children aged between 18 and 24 months hospitalized with acute respiratory tract infection. Real-time RT-PCR is a sensitive method for investigating the epidemiology and diseases associated with hMPV.

Evaluation of performance of human immunodeficiency virus antigen/antibody combination assays in Taiwan.

BACKGROUND: The fourth-generation human immunodeficiency virus (HIV) combination assay, which can simultaneously detect the presence of anti-HIV antibody and HIV antigen, has been shown to shorten the window period in HIV diagnosis compared with the third-generation HIV antibody immunoassay. This study was aimed to determine the performance of HIV combination assays in Taiwan, where the HIV-1 seroprevalence is 0.007% and HIV-2 infection has never been reported. METHODS: Performance of three fourth-generation HIV Ag/Ab combination assays (Dia.Pro, Wantai, and Bio-Rad) and one third-generation HIV Ab immunoassay (AxSYM HIV 1/2 gO) was assessed. RESULTS: A total of 152 specimens, including 86 confirmed HIV-seropositive and 66 HIV-seronegative samples, were used in the study. The sensitivity of four assays varied from 98.8% to 100%, and specificity varied from 98.5% to 100%. Performance of the 75 equivocal samples, the HIV status of which was confirmed later, in terms of negative prediction varied from 81.8% to 87.5%. The Bio-Rad and Dia.Pro assays exhibited higher sensitivity for the detection of p24 antigen among the three fourth-generation HIV combination assays. CONCLUSION: The three fourth-generation HIV Ag/Ab combination assays exhibited better sensitivity, specificity, and negative prediction than the third-generation HIV Ab immunoassay.

Molecular epidemiology of HIV type 1 subtypes in Taiwan: outbreak of HIV type 1 CRF07_BC infection in intravenous drug users.

In Taiwan, sexual transmission is responsible for most HIV-1 infections with two dominant subtypes, subtype B and CRF01_AE, distributing among homosexual and heterosexual groups, respectively. Recently, intravenous drug use has become an emerging route of HIV-1 transmission and contributed to a significant increase of HIV-1 infection. To characterize the HIV isolates responsible for the outbreak among intravenous drug users (IDUs), phylogenetic analysis was performed to analyze the protease/RT sequences amplified from HIV-1-infected IDUs at National Taiwan University Hospital and Taipei City STD Control Center. CRF07_BC, which is circulating in northern China, was demonstrated to account for the majority of HIV-1 infection in IDUs in the past 2 years. Although these Taiwanese CRF07_BC sequences shared the same breakpoint positions as those described in the CRF07_BC reference sequences, they formed a unique cluster in the phylogenetic tree, suggesting they originated from a founder virus. This finding was further supported by the relative low genetic diversity and unique sequence features. Our results demonstrated the emergence of CRF07_BC and its association with the HIV-1 outbreak among IDUs between 2004 and 2005 in Taiwan. This finding not only helps us to have a better understanding of the HIV evolution in Asia, but also has important implications for vaccine design in the future.