Human infection with a reassortant swine-origin influenza A(H1N2)v virus in Taiwan, 2021.

BACKGROUND: Influenza A virus infections occur in different species, causing mild-to-severe symptoms that lead to a heavy disease burden. H1N1, H1N2 and H3N2 are major subtypes of swine influenza A viruses in pigs and occasionally infect humans. METHODS: A case infected by novel influenza virus was found through laboratory surveillance system for influenza viruses. Clinical specimens were tested by virus culture and/or real-time RT-PCR. The virus was identified and characterized by gene sequencing and phylogenetic analysis. RESULTS: In 2021, for the first time in Taiwan, an influenza A(H1N2)v virus was isolated from a 5-year old girl who was suffering from fever, runny nose and cough. The isolated virus was designated A/Taiwan/1/2021(H1N2)v. Full-genome sequencing and phylogenetic analyses revealed that A/Taiwan/1/2021(H1N2)v is a novel reassortant virus containing hemagglutinin (HA) and neuraminidase (NA) gene segments derived from swine influenza A(H1N2) viruses that may have been circulating in Taiwan for decades, and the other 6 internal genes (PB2, PB2, PA, NP, M and NS) are from human A(H1N1)pdm09 viruses. CONCLUSION: Notably, the HA and NA genes of A/Taiwan/1/2021(H1N2)v separately belong to specific clades that are unique for Taiwanese swine and were proposed to be introduced from humans in different time periods. Bidirectional transmission between humans and swine contributes to influenza virus diversity and poses the next pandemic threat.

Evaluation of conventional and point-of-care real-time RT-PCR tests for the detection of SARS-CoV-2 through a pooled testing strategy.

BACKGROUND: The rapid identification and isolation of individuals infected with SARS-CoV-2 are fundamental countermeasures for the efficient control of the COVID-19 pandemic, which has affected millions of people around the world. Real-time RT-PCR is one of the most commonly applied reference methods for virus detection, and the use of pooled testing has been proposed as an effective way to increase the throughput of routine diagnostic tests. However, the clinical applicability of different types of real-time RT-PCR tests in a given group size remains inconclusive due to inconsistent regional disease prevalence and test demands. METHODS: In this study, the performance of one dual-target conventional and two point-of-care real-time RT-PCR tests in a 5-specimen pooled testing strategy for the detection of SARS-COV-2 was evaluated. RESULTS: We demonstrated the proof of concept that all of these real-time RT-PCR tests could feasibly detect SARS-CoV-2 from nasopharyngeal and oropharyngeal specimens that contain viral RNA loads in the range of 3.48 × 105 to 3.42 × 102 copies/ml through pooled testing in a group size of 5 with overall positive percent agreement (pooling vs. individual testing) ranging from 100% to 93.75%. Furthermore, the two POC real-time RT-PCR tests exhibited comparable sensitivity to that of the dual-target conventional one when clinical specimens were tested individually. CONCLUSION: Our findings support the feasibility of using real-time RT-PCR tests developed as a variety of platforms in routine laboratory detection of suspected COVID-19 cases through a pooled testing strategy that is beneficial to increasing the daily diagnostic capacity.

A nationwide survey of intraoperative management for one-lung ventilation in Taiwan: time to accountable for diversity in protective lung ventilation.

BACKGROUND: There is a major paradigm shift for intraoperative mechanical ventilator support by the introduction of lung protective ventilation strategies to reduce postoperative pulmonary complications and improve overall clinical outcomes in non-thoracic surgeries. However, there is currently a lack of standardized practice guideline for lung protection during thoracic surgeries that require one-lung ventilation (OLV). This study aimed to collect the expert opinions of the thoracic anesthesiologists in perioperative care for OLV surgery in Taiwan. METHODS: This prospective cross-sectional study was undertaken in 16 tertiary hospitals in Taiwan from January to February 2019. A structured survey form was distributed across the participating hospitals and the thoracic anesthesiologists were invited to complete the form voluntarily. The survey form consisted of three parts, including the basic information of the institutional anesthesia care standards, ventilatory settings for a proposed patient receiving OLV surgery and expert opinions on OLV. RESULTS: A total of 71 thoracic anesthesiologists responded to the survey. Double-lumen tubes are the most commonly used (93.8%) airway devices for OLV. The most commonly recommended ventilator setting during OLV is a tidal volume of 6-7 ml/kg PBW (67.6%) and a PEEP level of 4-6 cmH2O (73.5%). Dual controlled ventilator modes are used by 44.1% of the anesthesiologists. During OLV, high oxygen fraction (FiO2 > 0.8) is more commonly supplemented to achieve an oxygen saturation higher than 94%. The consensus of anesthesiologists on the indices for lung protection in thoracic surgery is considerably low. Large majority of the anesthesiologists (91.5%) highly recommend that an international clinical practice guideline on the protective lung ventilation strategy for thoracic anesthesia should be established. CONCLUSIONS: This study found that the thoracic anesthesiologists in Taiwan share certain common practices in ventilator support during OLV. However, they are concerned about the lack of fundamental clinical evidences to support the beneficial outcomes of the current lung protective strategies applicable to OLV. Large-scale trials are needed to form an evidence-based clinical practice guideline for thoracic anesthesia.

Seasonal dynamics of influenza viruses and age distribution of infected individuals across nine seasons covering 2009-2018 in Taiwan.

BACKGROUND/PURPOSE: A swine-origin influenza A/H1N1 virus (termed A/H1N1pdm) caused a pandemic in 2009 and has continuously circulated in the human population. To investigate its possible ecological effects on circulating influenza strains, the seasonal patterns of influenza viruses and the respective age distribution of infected patients were studies. METHODS: The data obtained from national influenza surveillance systems in Taiwan from July 2009 to June 2018 were analyzed. RESULTS: The A/H1N1pdm and A/H3N2 strains usually caused a higher ratio of severe to mild cases than influenza B. New variants of A/H1N1pdm and A/H3N2 emerged accompanied by a large epidemic peak. However, the new influenza B variants intended to circulate for several seasons before causing a large epidemic. The major group of outpatients affected by A/H1N1pdm were aged 13-23 years in the pandemic wave, and the age range of infected individuals gradually shifted to 24-49 and 0-6 years across seasons; A/H1N1pdm-infected inpatients were aged 24-49 years in 2009-2011, and the age range gradually switched to older groups aged 50-65 and >65 years. Individuals aged 0-6 or 24-49 years accounted for the majority of A/H3N2-infected outpatients across seasons, whereas most of the inpatients affected by A/H3N2 were aged >65 years. CONCLUSION: Understanding the effects of new variants and changes in dominant circulating viral strains on the age distribution of the affected human population, disease severity and epidemic levels is useful for the establishment of fine-tuned strategies for further improvement of influenza control.

Newly emerging mutations in the matrix genes of the human influenza A(H1N1)pdm09 and A(H3N2) viruses reduce the detection sensitivity of real-time reverse transcription-PCR.

New variants of the influenza A(H1N1)pdm09 and A(H3N2) viruses were detected in Taiwan between 2012 and 2013. Some of these variants were not detected in clinical specimens using a common real-time reverse transcription-PCR (RT-PCR) assay that targeted the conserved regions of the viral matrix (M) genes. An analysis of the M gene sequences of the new variants revealed that several newly emerging mutations were located in the regions where the primers or probes of the real-time RT-PCR assay bind; these included three mutations (G225A, T228C, and G238A) in the A(H1N1)pdm09 virus, as well as one mutation (C163T) in the A(H3N2) virus. These accumulated mismatch mutations, together with the previously identified C154T mutation of the A(H1N1)pdm09 virus and the C153T and G189T mutations of the A(H3N2) virus, result in a reduced detection sensitivity for the real-time RT-PCR assay. To overcome the loss of assay sensitivity due to mismatch mutations, we established a real-time RT-PCR assay using degenerate nucleotide bases in both the primers and probe and successfully increased the sensitivity of the assay to detect circulating variants of the human influenza A viruses. Our observations highlight the importance of the simultaneous use of different gene-targeting real-time RT-PCR assays for the clinical diagnosis of influenza.

Ischemic stroke following neck dissection in the elderly.

OBJECTIVE: Despite the known association of perioperative stroke with perioperative mortality, the prevalence of stroke following neck dissection in elderly patients remains unclear. This study compared the incidence of neck dissection-associated perioperative stroke in elderly and younger patients. MATERIALS AND METHODS: Totally, 1057 patients receiving neck dissection for head and neck cancers between June 2012 and July 2016 were reviewed at a single center. The patients were divided into elderly (age ≥65 years, n = 177) and younger (age <65 years, n = 880) groups (mean age: 72.3 ± 6.1 and 53.3 ± 7.6, respectively). Patient, anthropometric, and clinical characteristics including diagnoses, comorbidities, length of hospitalization, and incidence of perioperative stroke were compared. RESULTS: Younger patients were more likely to be male (P = 0.001) and to have received radiotherapy (P = 0.013). The prevalence of predisposing factors was higher in the elderly, including history of cerebral vascular accident (P = 0.002), hypertension (P < 0.001), diabetes (P < 0.001), and coronary artery disease (P < 0.001). Elderly patients also had longer hospitalizations (P < 0.001) for which previous radiotherapy was identified as a risk factor (adjusted odds ratio = 3.79, P = 0.0078). Postoperative ischemic stroke was diagnosed in two elderly patients (1.1%), whereas no ischemic strokes occurred in the younger group (P = 0.028). The overall incidence of perioperative stroke was 0.19%. CONCLUSION: The incidence of perioperative stroke was higher in the elderly than in the younger group. Furthermore, the prevalence of ischemic stroke in elderly patients associated with neck dissection was higher than that previously reported in the aged population after general head and neck operations, highlighting an increased risk of stroke in elderly patients receiving extensive neck surgery.

Clinical characteristics of arytenoid dislocation in patients undergoing bariatric/metabolic surgery: A STROBE-complaint retrospective study.

Tracheal intubation and the use of a large-bore calibrating orogastric (OG) tube have been reported to increase the incidence of arytenoid dislocation (AD) in patients undergoing bariatric/metabolic surgery. This study aimed at identifying the clinical characteristics of this patient subgroup.We retrospectively examined the clinical characteristics of 14 patients with AD (study group) who received tracheal intubation and OG insertion for bariatric/metabolic surgery between 2011 and 2016. For comparison, another group of 19 patients with postoperative AD collected from published literature and 3 patients from the authors' institute served as controls in whom only tracheal intubation was performed. Information on patient characteristics, anesthetic time, symptoms, time of symptom onset, intervention, and postinterventional impact on vocalization of the 2 groups were collected and compared.Patients in the study group were younger than those in the control group (38 [25-60] vs 54.5 [19-88] years, P = .03). Compared with the control group, anesthetic time (282.5 [155-360] vs 225 [25-480] minutes, P = .041) was longer and symptom onset (1.0 [0-6] vs 1.0 [0-6] days, P = .018) was more delayed in the study group. After closed reduction, the frequency of voice recovery was comparable in both groups in a time interval of 12 weeks (84.6% vs 92.9%, P = .59).Our report demonstrates that the clinical characteristics of patients with AD who received tracheal intubation and OG insertion for bariatric/metabolic surgery were different from those with postoperative AD receiving only tracheal intubation, highlighting the importance of implementing individualized strategies for AD prevention in this patient population.

Genetic analysis and evaluation of the reassortment of influenza B viruses isolated in Taiwan during the 2004-2005 and 2006-2007 epidemics.

Influenza B viruses were predominant in Taiwan during the 2004-2005 epidemic and both Victoria and Yamagata lineage viruses co-circulated. A reassortant influenza B virus that contained a Victoria lineage hemagglutinin (HA) gene and Yamagata lineage neuraminidase (NA) gene appeared first in 2002 and became predominant during the 2004-2005 epidemic. During the 2006-2007 epidemic, an influenza B outbreak occurred in Taiwan and only Victoria lineage viruses circulated. We characterized the viruses isolated in the 2006-2007 epidemic and found that the HA genes of influenza B viruses from that epidemic were highly similar to those from the 2004-2005 epidemic. We also analyzed the NA genes of isolates from the 2006-2007 epidemic and found that they all belonged to the Yamagata lineage and formed a new genetic subclade. Comparison of isolates from the 2004-2005 and 2006-2007 epidemics revealed four substitutions, N220K, E320D, K343R and E404K in NA genes. Although the HA sequences from the 2006-2007 epidemic were similar to those from the 2004-2005 epidemic, the NA sequences differed, suggesting distinct patterns of evolution of the HA and NA genes from 2004-2007 in Taiwan. This study emphasizes that the evolution of the NA genes may contribute to reemergence of influenza B viruses.

The circulation of subgenogroups B5 and C5 of enterovirus 71 in Taiwan from 2006 to 2007.

Enteroviruses (EVs) are among the most common pathogens in humans. EV71 infections have caused devastating enterovirus-associated outcomes in children globally. In this study, eleven EV71 isolates in Taiwan during 2006-2007 were selected for N-terminal VP1 gene analysis. A fragment of 403 bp on VP1 gene was sequenced and a phylogenetic analysis was performed. In addition, the full-length genome sequencing was carried out on two selected isolates. The results showed that subgenogroups of B5 and C5 had circulated and become predominant in Taiwan over the specified 2 years. Moreover, glutamic acid and threonine are found conservative at positions 43 and 58 on VP1 for genogroup B; however they are replaced by lysine and alanine, respectively, for genogroup C. To our knowledge, this is the first report describing the circulation of these two EV71 subgenogroups in Taiwan.

An epidemic surge of influenza A(H3N2) virus at the end of the 2016-2017 season in Taiwan with an increased viral genetic heterogeneity.

BACKGROUND: The epidemic of the 2016-2017 influenza season in Taiwan started early with moderate activity and was predominated by the influenza A(H3N2) virus. However, the influenza activity increased dramatically during the late stage of the 2016-2017 season. OBJECTIVES: The genetic and antigenic characteristics of the influenza A(H3N2) virus circulating in Taiwan during the 2016-2017 season were investigated. The relationship between virus clades and the patients' 2016-2017 vaccination histories was determined. STUDY DESIGN: Respiratory samples from patients with influenza-like illness in the community, clustered outbreaks, and inpatients with severe complications were tested for influenza virus. Influenza gene sequencing, phylogenetic analysis and hemagglutination inhibition assay were performed. RESULTS: A total of 1185, 690 and 353 cases of outpatients, inpatients and cluster events were tested positive for the A(H3N2) virus in this report. Multiple clades of the H3N2 virus co-circulated. New genetic variants were detected, including clade 3C.2a.1 with additional N121 K, K92R or T135 K mutations, 3C.2a.3a with T135 K and R150 K mutations and 3C.2a.4. The proportions of N121 K and T135 K mutations were continuously increasing. Most of the viruses (85.4%, 111/130) were antigenically related to the current vaccine strain. Infection by different clade H3N2 viruses did not correlate with immunization with the 2016-2017 vaccine. CONCLUSIONS: The data in this study indicate that antigenic drift is not the primary determinant of the epidemic wave at the end of the 2016-2017 season. The fitness changes in new variants, waning immunity and climatic changes are considered as possible contributors to the resurgence of the influenza A(H3N2) virus.

A virus-like particle vaccination strategy expands its tolerance to H3N2 antigenic drift by enhancing neutralizing antibodies against hemagglutinin stalk.

Seasonal influenza viruses impact public health annually due to their continual evolution. However, the current inactivated seasonal vaccines provide poor protection against antigenically drifted viruses and require periodical reformulation through hit-and-miss predictions about which strains will circulate during the next season. To reduce the impact caused by vaccine mismatch, we investigated the drift-tolerance of virus-like particles (VLP) as an improved vaccine candidate. The cross-protective humoral immunity elicited by the H3N2-VLP vaccine constructed for the 2011-2012 season was examined against viruses isolated from 2010 to 2015 in Taiwan evolving chronologically through clades 1, 4, 5, 3B and 3C, as well as viruses that were circulating globally in 2005, 2007 and 2009. Mouse immunization results demonstrated that H3N2-VLP vaccine elicited superior immunological breadth in comparison with the cognate conventional whole-inactivated virus (WIV) vaccine. Titers of neutralizing antibodies against heterologous strains representing each epidemic period in the VLP group were significantly higher than in the WIV group, indicating the antibody repertoire induced by the H3N2-VLPs was insensitive to viral antigenic drift over a span of at least 10 years. Noticeably, H3N2-VLP elicited higher levels of anti-stalk antibodies than H3N2-WIV, which offset the ineffectiveness caused by antigenic drift. This advantageous effect was attributed to the uncleaved precursor of their HA proteins. These results suggest a mechanism through which VLP-induced humoral immunity may better tolerate the evolutionary dynamics of influenza viruses and point to the possible use of a VLP vaccine as a method by which the requirement for annual updates of seasonal influenza vaccines may be diminished.

A novel H6N1 virus-like particle vaccine induces long-lasting cross-clade antibody immunity against human and avian H6N1 viruses.

Avian influenza A(H6N1) virus is one of the most common viruses isolated from migrating birds and domestic poultry in many countries. The first and only known case of human infection by H6N1 virus in the world was reported in Taiwan in 2013. This led to concern that H6N1 virus may cause a threat to public health. In this study, we engineered a recombinant H6N1 virus-like particle (VLP) and investigated its vaccine effectiveness compared to the traditional egg-based whole inactivated virus (WIV) vaccine. The H6N1-VLPs exhibited similar morphology and functional characteristics to influenza viruses. Prime-boost intramuscular immunization in mice with unadjuvanted H6N1-VLPs were highly immunogenic and induced long-lasting antibody immunity. The functional activity of the VLP-elicited IgG antibodies was proved by in vitro seroprotective hemagglutination inhibition and microneutralization titers against the homologous human H6N1 virus, as well as in vivo viral challenge analyses which showed H6N1-VLP immunization significantly reduced viral load in the lung, and protected against human H6N1 virus infection. Of particular note, the H6N1-VLPs but not the H6N1-WIVs were able to confer cross-reactive humoral immunity; antibodies induced by H6N1-VLP vaccine robustly inhibited the hemagglutination activities and in vitro replication of distantly-related heterologous avian H6N1 viruses. Furthermore, the H6N1-VLPs were found to elicit significantly greater anti-HA2 antibody responses in immunized mice than H6N1-WIVs. Collectively, we demonstrated for the first time a novel H6N1-VLP vaccine that effectively provides broadly protective immunity against both human and avian H6N1 viruses. These results, which uncover the underlying mechanisms for induction of wide-range immunity against influenza viruses, may be useful for future influenza vaccine development.

Characterization of influenza A (H7N9) viruses isolated from human cases imported into Taiwan.

A novel avian influenza A (H7N9) virus causes severe human infections and was first identified in March 2013 in China. The H7N9 virus has exhibited two epidemiological peaks of infection, occurring in week 15 of 2013 and week 5 of 2014. Taiwan, which is geographically adjacent to China, faces a large risk of being affected by this virus. Through extensive surveillance, launched in April 2013, four laboratory-confirmed H7N9 cases imported from China have been identified in Taiwan. The H7N9 virus isolated from imported case 1 in May 2013 (during the first wave) was found to be closest genetically to a virus from wild birds and differed from the prototype virus, A/Anhui/1/2013, in the MP gene. The other three imported cases were detected in December 2013 and April 2014 (during the second wave). The viruses isolated from cases 2 and 4 were similar in the compositions of their 6 internal genes and distinct from A/Anhui/1/2013 in the PB2 and MP genes, whereas the virus isolated from case 3 exhibited a novel reassortment that has not been identified previously and was different from A/Anhui/1/2013 in the PB2, PA and MP genes. The four imported H7N9 viruses share similar antigenicity with A/Anhui/1/2013, and their HA and NA genes grouped together in their respective phylogenies. In contrast with the HA and NA genes, which exhibited a smaller degree of diversity, the internal genes were heterogeneous and provided potential distinctions between transmission sources in terms of both geography and hosts. It is important to strengthen surveillance of influenza and to share viral genetic data in real-time for reducing the threat of rapid and continuing evolution of H7N9 viruses.

Early findings of oseltamivir-resistant pandemic (H1N1) 2009 influenza A viruses in Taiwan.

In this study, we investigated the frequency of oseltamivir resistance in pandemic (H1N1) 2009 influenza A viruses in Taiwan and characterized the resistant viruses. From May 2009 to January 2010, 1187 pandemic H1N1 virus-positive cases in Taiwan were tested for the H275Y substitution in the neuraminidase (NA) gene that confers resistance to oseltamivir. Among them, eight hospitalized cases were found to be infected with virus encoding the H275Y substitution in their original specimens collected after oseltamivir treatment. The epidemiologic investigation indicated that each of the cases occurred sporadically and there was no evidence of further transmission. We monitored the variation of amino acid residues at position 275 of the NA gene in a series of specimens taken at various time-points and observed that viruses encoding the H275Y substitution differ in their fitness in vivo and in MDCK cells. Phylogenetic analysis indicated that the hemagglutinin (HA) sequences of oseltamivir-resistant pandemic H1N1 viruses exhibited greater diversity than the NA sequences and progressive changes of the HA genes from clade A1 into A2 and from there into clade A3 were observed. The resistant viruses seemed to occur in combination with diverse HA genes and a dominant NA gene. Enzymatic analysis of the viruses revealed that the ratio of NA/HA activities in oseltamivir-resistant viruses was reduced considerably compared to those in wild-type ones.

A new antigenic variant of human influenza A (H3N2) virus isolated from airport and community surveillance in Taiwan in early 2009.

A new variant of influenza A H3N2 virus emerged in January 2009 and became the dominant strain in Taiwan in April 2009. The variant was also detected in imported cases from various regions, including East and Southeast Asia and North America, indicating that it has circulated globally. Compared to the 2009-2010 vaccine strain, A/Brisbane/10/2007, the hemagglutinin gene of this variant exhibited five substitutions, E62K, N144K, K158N, K173Q and N189K, which are located in the antigenic sites E, A, B, D and B respectively, and it was antigenically distinct from A/Brisbane/10/2007 with more than eight-fold titer reduction in the hemagglutination inhibition reaction. The A/Perth/16/2009 (H3N2)-like virus recommended by World Health Organization for use in the 2010 southern hemisphere and 2010-2011 northern influenza seasons exhibited the same substitutions like this new variant. In addition to regional or community influenza surveillance, the imported cases or airport fever screening surveillance may be a good resource to monitor the evolution of the virus and benefit the real-time information of global influenza circulation.