Clock component OsPRR73 positively regulates rice salt tolerance by modulating OsHKT2;1-mediated sodium homeostasis.

The roles of clock components in salt stress tolerance remain incompletely characterized in rice. Here, we show that, among OsPRR (Oryza sativa Pseudo-Response Regulator) family members, OsPRR73 specifically confers salt tolerance in rice. Notably, the grain size and yield of osprr73 null mutants were significantly decreased in the presence of salt stress, with accumulated higher level of reactive oxygen species and sodium ions. RNA sequencing and biochemical assays identified OsHKT2;1, encoding a plasma membrane-localized Na+ transporter, as a transcriptional target of OsPRR73 in mediating salt tolerance. Correspondingly, null mutants of OsHKT2;1 displayed an increased tolerance to salt stress. Immunoprecipitation-mass spectrometry (IP-MS) assays further identified HDAC10 as nuclear interactor of OsPRR73 and co-repressor of OsHKT2;1. Consistently, H3K9ac histone marks at OsHKT2;1 promoter regions were significantly reduced in osprr73 mutant. Together, our findings reveal that salt-induced OsPRR73 expression confers salt tolerance by recruiting HDAC10 to transcriptionally repress OsHKT2;1, thus reducing cellular Na+ accumulation. This exemplifies a new molecular link between clock components and salt stress tolerance in rice.

Molecular and metabolic insights into purplish leaf coloration through the investigation of two mulberry (Morus alba) genotypes.

BACKGROUND: Leaf coloration in plants, attributed to anthocyanin compounds, plays a crucial role in various physiological functions, and also for pharmaceutical and horticultural uses. However, the molecular mechanisms governing leaf coloration and the physiological significance of anthocyanins in leaves remain poorly understood. RESULTS: In this study, we investigated leaf color variation in two closely related mulberry genotypes, one with purplish-red young leaves (EP) and another with normal leaf color (EW). We integrated transcriptomic and metabolomic approaches to gain insights into the metabolic and genetic basis of purplish-red leaf development in mulberry. Our results revealed that flavonoid biosynthesis, particularly the accumulation of delphinidin-3-O-glucoside, is a key determinant of leaf color. Additionally, the up-regulation of CHS genes and transcription factors, including MYB family members, likely contributes to the increased flavonoid content in purplish-red leaves. CONCLUSION: These findings enhance our understanding of the molecular mechanisms responsible for the purplish coloration observed in mulberry leaves and also offer supporting evidence for the hypothesis that anthocyanins serve a protective function in plant tissues until the processes of light absorption and carbon fixation reach maturity, thereby ensuring a balanced equilibrium between energy capture and utilization.

Medium-term exposure to size-fractioned particulate matter and asthma exacerbations in China: A longitudinal study of asthmatics with poor medication adherence.

BACKGROUND: Studies have shown that short- and long-term exposure to particulate matter (PM) can increase the risk of asthma morbidity and mortality. However, the effect of medium-term exposure remains unknown. We aim to examine the effect of medium-term exposure to size-fractioned PM on asthma exacerbations among asthmatics with poor medication adherence. METHODS: We conducted a longitudinal study in China based on the National Mobile Asthma Management System Project that specifically and routinely followed asthma exacerbations in asthmatics with poor medication adherence from April 2017 to May 2019. High-resolution satellite remote-sensing data were used to estimate each participant's medium-term exposure (on average 90 days) to size-fractioned PM (PM1, PM2.5, and PM10) based on the residential address and the date of the follow-up when asthma exacerbations (e.g., hospitalizations and emergency room visits) occurred or the end of the follow-up. The Cox proportional hazards model was employed to examine the hazard ratio of asthma exacerbations associated with each PM after controlling for sex, age, BMI, education level, geographic region, and temperature. RESULTS: Modelling results revealed nonlinear exposure-response associations of asthma exacerbations with medium-term exposure to PM1, PM2.5, and PM10. Specifically, for emergency room visits, we found an increased hazard ratio for PM1 above 22.8 µg/m3 (1.060, 95 % CI: 1.025-1.096, per 1 µg/m3 increase), PM2.5 above 38.2 µg/m3 (1.032, 95 % CI: 1.010-1.054), and PM10 above 78.6 µg/m3 (1.019, 95 % CI: 1.006-1.032). For hospitalizations, we also found an increased hazard ratio for PM1 above 20.3 µg/m3 (1.055, 95 % CI: 1.001-1.111) and PM2.5 above 39.2 µg/m3 (1.038, 95 % CI: 1.003-1.074). Furthermore, the effects of PM were greater for a longer exposure window (90-180 days) and among participants with a high BMI. CONCLUSION: This study suggests that medium-term exposure to PM is associated with an increased risk of asthma exacerbations in asthmatics with poor medication adherence, with a higher risk from smaller PM.

Rice CIRCADIAN CLOCK ASSOCIATED 1 transcriptionally regulates ABA signaling to confer multiple abiotic stress tolerance.

The circadian clock facilitates the survival and reproduction of crop plants under harsh environmental conditions such as drought and osmotic and salinity stresses, mainly by reprogramming the endogenous transcriptional landscape. Nevertheless, the genome-wide roles of core clock components in rice (Oryza sativa L.) abiotic stress tolerance are largely uncharacterized. Here, we report that CIRCADIAN CLOCK ASSOCIATED1 (OsCCA1), a vital clock component in rice, is required for tolerance to salinity, osmotic, and drought stresses. DNA affinity purification sequencing coupled with transcriptome analysis identified 692 direct transcriptional target genes of OsCCA1. Among them, the genes involved in abscisic acid (ABA) signaling, including group A protein phosphatase 2C genes and basic region and leucine zipper 46 (OsbZIP46), were substantially enriched. Moreover, OsCCA1 could directly bind the promoters of OsPP108 and OsbZIP46 to activate their expression. Consistently, oscca1 null mutants generated via genome editing displayed enhanced sensitivities to ABA signaling. Together, our findings illustrate that OsCCA1 confers multiple abiotic stress tolerance likely by orchestrating ABA signaling, which links the circadian clock with ABA signaling in rice.

Engineering Cytochrome P450BM3 Enzymes for Direct Nitration of Unsaturated Hydrocarbons.

Applications of the peroxidase activity of cytochrome P450 enzymes in synthetic chemistry remain largely unexplored. We present herein a protein engineering strategy to increase cytochrome P450BM3 peroxidase activity for the direct nitration of aromatic compounds and terminal aryl-substituted olefins in the presence of a dual-functional small molecule (DFSM). Site-directed mutations of key active-site residues allowed the efficient regulation of steric effects to limit substrate access and, thus, a significant decrease in monooxygenation activity and increase in peroxidase activity. Nitration of several phenol and aniline compounds also yielded ortho- and para-nitration products with moderate-to-high total turnover numbers. Besides direct aromatic nitration by P450 variants using nitrite as a nitrating agent, we also demonstrated the use of the DFSM-facilitated P450 peroxidase system for the nitration of the vinyl group of styrene and its derivatives.

Heterogeneity in Estimates of Incidence and Prevalence of Narcolepsy: A Systematic Review and Meta-Regression Analysis.

INTRODUCTION: Narcolepsy is a chronic neurological disorder. The diagnostic criteria of narcolepsy evolve from clinical symptoms to molecular biomarkers, along with the understanding of its clinical nature and pathogenesis. Estimates of incidence and prevalence of narcolepsy vary between studies, while the contribution of changing diagnostic criteria to the variation remains unclear. We aimed to explore sources of heterogeneity in estimates of incidence and prevalence, with a particular focus on diagnostic criteria. METHODS: We searched 5 databases for observational studies on the incidence or prevalence of narcolepsy published before October 14, 2021. Subgroup analyses and meta-regression were used to assess the impact of diagnostic criteria on incidence/prevalence of narcolepsy after adjusting for age-group, region, study period, vaccination status, index date, and type of narcolepsy. RESULTS: Thirty-five studies were selected from 2,833 articles. The estimates of incidence and prevalence were wide-ranging with high heterogeneity (incidence I2 = 99.8%; prevalence I2 = 99.7%), from 0.06 to 6.56 per 100,000 person-years for incidence and from 1.05 to 79.40 per 100,000 population for prevalence, respectively. Totally 10 diagnostic criteria were used, including the 1st revised edition of International Classification of Diseases (ICSD-1), ICSD-2, ICSD-3, the 8th revision of International Classification of Diseases (ICD-8), ICD-9, ICD-10, Brighton collaboration case definition (Brighton), Mayo classification, the Ullanlinna Narcolepsy Scale, and clinical symptoms with the multiple sleep latency test. ICD tended to provide higher estimates of incidence/prevalence than Brighton (incidence odds ratio [OR] 1.38, [95% CI: 1.02, 1.86]; prevalence OR 1.50, [95% CI: 1.04, 2.39]). No significant difference was found in estimates of two rates between ICSD and Brighton. The incidence was higher for children than adults (OR 1.61, [95% CI: 1.25, 2.07]) and for individuals vaccinated with Pandemrix than those unvaccinated (OR 6.49, [95% CI: 3.86, 10.91]). CONCLUSIONS: Estimates of incidence/prevalence of narcolepsy could not be pooled reliably with substantial heterogeneity. Incidence/prevalence studies using ICSD and Brighton provided lower estimates than studies using ICD and other criteria. Diagnostic criteria should be standardized when comparing or pooling the incidence/prevalence to understand the epidemiology of narcolepsy. Future studies are needed to focus on the at-risk population for the etiology investigation of narcolepsy.

Case Fatality Risk of the First Pandemic Wave of Coronavirus Disease 2019 (COVID-19) in China.

BACKGROUND: To assess the case fatality risk (CFR) of COVID-19 in mainland China, stratified by region and clinical category, and estimate key time-to-event intervals. METHODS: We collected individual information and aggregated data on COVID-19 cases from publicly available official sources from 29 December 2019 to 17 April 2020. We accounted for right-censoring to estimate the CFR and explored the risk factors for mortality. We fitted Weibull, gamma, and log-normal distributions to time-to-event data using maximum-likelihood estimation. RESULTS: We analyzed 82 719 laboratory-confirmed cases reported in mainland China, including 4632 deaths and 77 029 discharges. The estimated CFR was 5.65% (95% confidence interval [CI], 5.50-5.81%) nationally, with the highest estimate in Wuhan (7.71%) and lowest in provinces outside Hubei (0.86%). The fatality risk among critical patients was 3.6 times that of all patients and 0.8-10.3-fold higher than that of mild-to-severe patients. Older age (odds ratio [OR], 1.14 per year; 95% CI, 1.11-1.16) and being male (OR, 1.83; 95% CI, 1.10-3.04) were risk factors for mortality. The times from symptom onset to first healthcare consultation, to laboratory confirmation, and to hospitalization were consistently longer for deceased patients than for those who recovered. CONCLUSIONS: Our CFR estimates based on laboratory-confirmed cases ascertained in mainland China suggest that COVID-19 is more severe than the 2009 H1N1 influenza pandemic in hospitalized patients, particularly in Wuhan. Our study provides a comprehensive picture of the severity of the first wave of the pandemic in China. Our estimates can help inform models and the global response to COVID-19.

A clock regulatory module is required for salt tolerance and control of heading date in rice.

The circadian clock plays multiple roles in plant stress responses and developmental transition phases. Nevertheless, the underlying molecular mechanisms and individual clock components that coordinately regulate important agronomic traits of rice such as salt tolerance and heading date remain to be elucidated. Here, we identify a rice ternary repressive protein complex composed of OsELF4a, OsELF3-1 and OsLUX, which was designated as OsEC1 in analogy to a similar complex in Arabidopsis. OsELF4a physically interacts with OsELF3-1 and OsELF3-2 in nucleus, whilst OsELF3-1 rather than OsELF3-2 strongly interacts with OsLUX, a Myb-domain containing transcriptional factor. Phenotypic analyses show a role for this complex in heading and salt tolerance. The loss-of-function mutants of OsEC1 exhibit lower survival rate under salt stress and late heading date. Transcriptomic profiling together with biochemical assays identified the GIGANTEA homologue OsGI as a direct transcriptional target of OsEC1. Notably, the osgi-101 mutant, generated by CRISPR/Cas9, is salt tolerant and exhibits early heading date in long day conditions. Together, our findings characterized a transcriptional module in rice composed by the OsEC1 repressing OsGI, which links the circadian clock with salt tolerance and control of heading date.

Effectiveness of Live Poultry Market Interventions on Human Infection with Avian Influenza A(H7N9) Virus, China.

Various interventions for live poultry markets (LPMs) have emerged to control outbreaks of avian influenza A(H7N9) virus in mainland China since March 2013. We assessed the effectiveness of various LPM interventions in reducing transmission of H7N9 virus across 5 annual waves during 2013-2018, especially in the final wave. With the exception of waves 1 and 4, various LPM interventions reduced daily incidence rates significantly across waves. Four LPM interventions led to a mean reduction of 34%-98% in the daily number of infections in wave 5. Of these, permanent closure provided the most effective reduction in human infection with H7N9 virus, followed by long-period, short-period, and recursive closures in wave 5. The effectiveness of various LPM interventions changed with the type of intervention across epidemics. Permanent LPM closure should be considered to maintain sufficient effectiveness of interventions and prevent the recurrence of H7N9 epidemics.

Cytotoxic secondary metabolites from the vulnerable conifer Cephalotaxus oliveri and its associated endophytic fungus Alternaria alternate Y-4-2.

Rare and endangered plants (REPs) and their associated endophytes survived in unique habitats are promising sources for natural product-derived drug discovery. In this study, six new (cephaloverines A-F, 1-6, resp.) and 16 known (11-26) cephalotaxine-type alkaloids, together with three new (oliverbiflavones A-C, 7-9, resp.) and 11 known (27-37) biflavonoids were isolated and characterized from the twigs and leaves of Cephalotaxus oliveri, an endangered plant endemic to China. Meanwhile, a preliminary investigation on the secondary metabolites from a selected fungal endophyte (i.e., Alternaria alternate Y-4-2) associated with the title plant led to the isolation of 21 structurally distinct polyketides including one new dimeric xanthone (10). The new structures (1-10) with the absolute configurations were determined by detailed spectroscopic analyses, electronic circular dichroism (ECD) or Na2MoO4-induced ECD, the modified Mosher's method, and some chemical transformations. Compounds 1-4 are the first representatives of naturally occurring N-oxides of cephalotaxine esters, while compounds 7-9 have a special structural feature of having a C-methylated biflavonoid skeleton. The Cephalotaxus alkaloids with ester side-chains at C-3 (1-6, 13-22, and 26) and four biflavonoids (27-29 and 34) were found to show pronounced cytotoxicities against a small panel of human cancer cell lines (A549, NCI-H460, HL60, NCI-H929, and RPMI-8226), with IC50 values mainly ranging from 0.003 to 9.34 µM. The most potent compound, deoxyharringtonine (16), generally exhibited IC50 values less than 10 nM. The structure-activity relationship (SAR) of the aforementioned Cephalotaxus alkaloids was briefly discussed.

Assessment of Human-to-Human Transmissibility of Avian Influenza A(H7N9) Virus Across 5 Waves by Analyzing Clusters of Case Patients in Mainland China, 2013-2017.

Background: The 2016-17 epidemic of human infections with avian influenza A(H7N9) virus was alarming, due to the surge in reported cases across a wide geographic area and the emergence of highly-pathogenic A(H7N9) viruses. Our study aimed to assess whether the human-to-human transmission risk of A(H7N9) virus has changed across the 5 waves since 2013. Methods: Data on human cases and clusters of A(H7N9) virus infection were collected from the World Health Organization, open access national and provincial reports, informal online sources, and published literature. We compared the epidemiological characteristics of sporadic and cluster cases, estimated the relative risk (RR) of infection in blood relatives and non-blood relatives, and estimated the bounds on the effective reproductive number (Re) across waves from 2013 through September 2017. Results: We identified 40 human clusters of A(H7N9) virus infection, with a median cluster size of 2 (range 2-3). The overall RR of infection in blood relatives versus non-blood relatives was 1.65 (95% confidence interval [CI]: 0.88, 3.09), and was not significantly different across waves (χ2 = 2.66, P = .617). The upper limit of Re for A(H7N9) virus was 0.12 (95% CI: 0.10, 0.14) and was not significantly different across waves (χ2 = 1.52, P = .822). Conclusions: The small cluster size and low Re suggest that human-to-human transmissibility of A(H7N9) virus has not changed over time and remains limited to date. Continuous assessment of A(H7N9) virus infections and human case clusters is of crucial importance for public health.

Prolonged Evolution of Virus-Specific Memory T Cell Immunity after Severe Avian Influenza A (H7N9) Virus Infection.

Since 2013, influenza A H7N9 virus has emerged as the most common avian influenza virus subtype causing human infection, and it is associated with a high fatality risk. However, the characteristics of immune memory in patients who have recovered from H7N9 infection are not well understood. We assembled a cohort of 45 H7N9 survivors followed for up to 15 months after infection. Humoral and cellular immune responses were analyzed in sequential samples obtained at 1.5 to 4 months, 6 to 8 months, and 12 to 15 months postinfection. H7N9-specific antibody concentrations declined over time, and protective antibodies persisted longer in severely ill patients admitted to the intensive care unit (ICU) and patients presenting with acute respiratory distress syndrome (ARDS) than in patients with mild disease. Frequencies of virus-specific gamma interferon (IFN-γ)-secreting T cells were lower in critically ill patients requiring ventilation than in patients without ventilation within 4 months after infection. The percentages of H7N9-specific IFN-γ-secreting T cells tended to increase over time in patients ≥60 years or in critically ill patients requiring ventilation. Elevated levels of antigen-specific CD8+ T cells expressing the lung-homing marker CD49a were observed at 6 to 8 months after H7N9 infection compared to those in samples obtained at 1.5 to 4 months. Our findings indicate the prolonged reconstruction and evolution of virus-specific T cell immunity in older or critically ill patients and have implications for T cell-directed immunization strategies.IMPORTANCE Avian influenza A H7N9 virus remains a major threat to public health. However, no previous studies have determined the characteristics and dynamics of virus-specific T cell immune memory in patients who have recovered from H7N9 infection. Our findings showed that establishment of H7N9-specific T cell memory after H7N9 infection was prolonged in older and severely affected patients. Severely ill patients mounted lower T cell responses in the first 4 months after infection, while T cell responses tended to increase over time in older and severely ill patients. Higher levels of antigen-specific CD8+ T cells expressing the lung-homing marker CD49a were detected at 6 to 8 months after infection. Our results indicated a long-term impact of H7N9 infection on virus-specific memory T cells. These findings advance our understanding of the dynamics of virus-specific memory T cell immunity after H7N9 infection, which is relevant to the development of T cell-based universal influenza vaccines.

Effects of air pollutants on occurrences of influenza-like illness and laboratory-confirmed influenza in Hefei, China.

Accumulating evidence suggests that air pollution is a risk factor for adverse respiratory and cardiovascular health outcomes. However, the different impacts of exposure to air pollutants on influenza virus activity and influenza-like illness (ILI) have not been well documented in epidemiological studies. We examined the association between air pollutants of particular matters < 2.5 µm (PM2.5), particular matters < 10 µm (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), and influenza occurrences in Hefei, China, from December 2013 to December 2015 by generalized Poisson additive regression models. The result suggested that PM2.5 and PM10 had similar effects on clinical ILI and influenza incidence. PM10 was negatively associated with clinical ILI (relative risk (RR) 0.980, 95% confidence interval (CI) 0.974-0.987), while PM2.5 were positively associated with clinical ILI (RR 1.040; 95% CI 1.032-1.049). RRs for the laboratory-confirmed cases of influenza were 0.813 (95% CI, 0.755-0.875) for PM10 and 1.216 (95% CI, 1.134-1.304) for PM2.5. Nevertheless, the impacts of SO2 and NO2 on ILI and influenza were distinct. SO2 had significant influence on laboratory-confirmed influenza and had no significant linear relationship with ILI. NO2 was negatively correlated with influenza but had no obvious effect on clinical ILI cases. The present study contributes novel evidence on understanding of the effects of various air pollutants on influenza activities, and these findings can be useful and important for the development of influenza surveillance and early warning systems.

Variation in Influenza B Virus Epidemiology by Lineage, China.

We used national sentinel surveillance data in China for 2005-2016 to examine the lineage-specific epidemiology of influenza B. Influenza B viruses circulated every year with relatively lower activity than influenza A. B/Yamagata was more frequently detected in adults than in children.

Changing Geographic Patterns and Risk Factors for Avian Influenza A(H7N9) Infections in Humans, China.

The fifth epidemic wave of avian influenza A(H7N9) virus in China during 2016-2017 demonstrated a geographic range expansion and caused more human cases than any previous wave. The factors that may explain the recent range expansion and surge in incidence remain unknown. We investigated the effect of anthropogenic, poultry, and wetland variables on all epidemic waves. Poultry predictor variables became much more important in the last 2 epidemic waves than they were previously, supporting the assumption of much wider H7N9 transmission in the chicken reservoir. We show that the future range expansion of H7N9 to northern China may increase the risk of H7N9 epidemic peaks coinciding in time and space with those of seasonal influenza, leading to a higher risk of reassortments than before, although the risk is still low so far.

Endogenous Hydrogen Sulfide Ameliorates NOX4 Induced Oxidative Stress in LPS-Stimulated Macrophages and Mice.

BACKGROUND/AIMS: Sepsis is a severe and complicated syndrome that is characterized by dysregulation of host inflammatory responses and organ failure. Cystathionine-γ-lyase (CSE)/ hydrogen sulfide (H2S) has potential anti-inflammatory activities in a variety of inflammatory diseases. NADPH oxidase 4 (Nox4), a member of the NADPH oxidases, is the major source of reactive oxygen species (ROS) and its expression is increased in sepsis, but its function in CSE-mediated anti-inflammatory activities remains unknown. METHODS: Macrophages were either transfected with CSE, Nox4 siRNA or transduced with lentiviral vector encoding CSE or Nox4, and then stimulated with lipopolysaccharide (LPS). The expression of inflammatory mediators and signaling pathway activation were measured by quantitative PCR (qPCR), ELISA, and immunoblotting. LPS-induced shock severity in WT, Nox4 knockdown and CSE knockout (CSE-/-) mice was assessed. RESULTS: Here we showed that CSE and Nox4 were upregulated in macrophage and mouse in response to LPS. After LPS stimulation, the inflammatory responses were significantly ameliorated by lentiviral Nox4 shRNA knockdown, but were exacerbated by lentiviral overexpressing Nox4. Furthermore, Nox4 mediated inflammation through PI3K/Akt and p-p38 mitogen-activated protein kinase signal pathway. Notably, CSE knockout served to amplify the inflammatory cascade by increasing Nox4-ROS signaling activation in septic mice and macrophage. Similarly, the enhanced production of inflammatory mediators by macrophages was reduced by CSE overexpression. CONCLUSION: Thus, we demonstrated that CSE/H2S attenuated LPS-induced sepsis against oxidative stress and inflammation damage probably largely through mediated Nox4 pathway.

Impact of weather factors on influenza hospitalization across different age groups in subtropical Hong Kong.

Accumulating evidence demonstrates the significant influence of weather factors, especially temperature and humidity, on influenza seasonality. However, it is still unclear whether temperature variation within the same day, that is diurnal temperature range (DTR), is related to influenza seasonality. In addition, the different effects of weather factors on influenza seasonality across age groups have not been well documented in previous studies. Our study aims to explore the effects of DTR and humidity on influenza seasonality, and the differences in the association between weather factors and influenza seasonality among different age groups in Hong Kong, China. Generalized additive models were conducted to flexibly assess the impact of DTR, absolute humidity (vapor pressure, VP), and relative humidity on influenza seasonality in Hong Kong, China, from January 2012 to December 2016. Stratified analyses were performed to determine if the effects of weather factors differ across age groups (< 5, 5-9, 10-64, and > 64 years). The results suggested that DTR, absolute humidity, and relative humidity were significantly related to influenza seasonality in dry period (when VP is less than 20 mb), while no significant association was found in humid period (when VP is greater than 20 mb). The percentage changes of hospitalization rates due to influenza associated with per unit increase of weather factors in the very young children (age 0-4) and the elderly (age 65+) were higher than that in the adults (age 10-64). Diurnal temperature range is significantly associated with influenza seasonality in dry period, and the effects of weather factors differ across age groups in Hong Kong, China.

Possible interference between seasonal epidemics of influenza and other respiratory viruses in Hong Kong, 2014-2017.

BACKGROUND: Unlike influenza viruses, little is known about the prevalence and seasonality of other respiratory viruses because laboratory surveillance for non-influenza respiratory viruses is not well developed or supported in China and other resource-limited countries. We studied the interference between seasonal epidemics of influenza viruses and five other common viruses that cause respiratory illnesses in Hong Kong from 2014 to 2017. METHODS: The weekly laboratory-confirmed positive rates of each virus were analyzed from 2014 to 2017 in Hong Kong to describe the epidemiological trends and interference between influenza viruses, respiratory syncytial virus (RSV), parainfluenza virus (PIV), adenovirus, enterovirus and rhinovirus. A sinusoidal model was established to estimate the peak timing of each virus by phase angle parameters. RESULTS: Seasonal features of the influenza viruses, PIV, enterovirus and adenovirus were obvious, whereas annual peaks of RSV and rhinovirus were not observed. The incidence of the influenza viruses usually peaked in February and July, and the summer peaks in July were generally caused by the H3 subtype of influenza A alone. When influenza viruses were active, other viruses tended to have a low level of activity. The peaks of the influenza viruses were not synchronized. An epidemic of rhinovirus tended to shift the subsequent epidemics of the other viruses. CONCLUSION: The evidence from recent surveillance data in Hong Kong suggests that viral interference during the epidemics of influenza viruses and other common respiratory viruses might affect the timing and duration of subsequent epidemics of a certain or several viruses.

Excess pneumonia and influenza mortality attributable to seasonal influenza in subtropical Shanghai, China.

BACKGROUND: Disease burden attributable to influenza is substantial in subtropical regions. Our study aims to estimate excess pneumonia and influenza (P&I) mortality associated with influenza by subtypes/lineages in Shanghai, China, 2010-2015. METHODS: Quasi-Poisson regression models were fitted to weekly numbers of deaths from causes coded as P&I for Shanghai general and registered population. Three proxies for influenza activity were respectively used as an explanatory variable. Long-term trend, seasonal trend and absolute humidity were adjusted for as confounding factors. The outcome measurements of excess P&I mortality associated with influenza subtypes/lineages were derived by subtracting the baseline mortality from fitted mortality. RESULTS: Excess P&I mortality associated with influenza were 0.22, 0.30, and 0.23 per 100,000 population for three different proxies in Shanghai general population, lower than those in registered population (0.34, 0.48, and 0.36 per 100,000 population). Influenza B (Victoria) lineage did not contribute to excess P&I mortality (P = 0.206) while influenza B (Yamagata) lineage did (P = 0.044). Influenza-associated P&I mortality was high in the elderly population. CONCLUSIONS: Seasonal influenza A virus had a higher P&I mortality than influenza B virus, while B (Yamagata) lineage is the dominant lineage attributable to P&I mortality.

Different responses of influenza epidemic to weather factors among Shanghai, Hong Kong, and British Columbia.

Weather factors have long been considered as key sources for regional heterogeneity of influenza seasonal patterns. As influenza peaks coincide with both high and low temperature in subtropical cities, weather factors may nonlinearly or interactively affect influenza activity. This study aims to assess the nonlinear and interactive effects of weather factors with influenza activity and compare the responses of influenza epidemic to weather factors in two subtropical regions of southern China (Shanghai and Hong Kong) and one temperate province of Canada (British Columbia). Weekly data on influenza activity and weather factors (i.e., mean temperature and relative humidity (RH)) were obtained from pertinent government departments for the three regions. Absolute humidity (AH) was measured by vapor pressure (VP), which could be converted from temperature and RH. Generalized additive models were used to assess the exposure-response relationship between weather factors and influenza virus activity. Interactions of weather factors were further assessed by bivariate response models and stratification analyses. The exposure-response curves of temperature and VP, but not RH, were consistent among three regions/cities. Bivariate response model revealed a significant interactive effect between temperature (or VP) and RH (P < 0.05). Influenza peaked at low temperature or high temperature with high RH. Temperature and VP are important weather factors in developing a universal model to explain seasonal outbreaks of influenza. However, further research is needed to assess the association between weather factors and influenza activity in a wider context of social and environmental conditions.