Evolutionary trajectories of two distinct avian influenza epidemics: Parallelisms and divergences

Influenza A virus can quickly acquire genetic mutations that may be associated with increased virulence, host switching or antigenic changes. To provide new insights into the evolutionary dynamics and the adaptive strategies of distinct avian influenza lineages in response to environmental and host factors, we compared two distinct avian influenza epidemics caused by the H7N1 and H7N3 subtypes that circulated under similar epidemiological conditions, including the same domestic species reared in the same densely populated poultry area for similar periods of time.The two strains appear to have experienced largely divergent evolution: the H7N1 viruses evolved into a highly pathogenic form, while the H7N3 did not. However, a more detailed molecular and evolutionary analysis revealed several common features: (i) the independent acquisition of 32 identical mutations throughout the entire genome; (ii) the evolution and persistence of two sole genetic groups with similar genetic characteristics; (iii) a comparable pattern of amino acid variability of the HA proteins during the low pathogenic epidemics; and (iv) similar rates of nucleotide substitutions. These findings suggest that the evolutionary trajectories of viruses with the same virulence level circulating in analogous epidemiological conditions may be similar. In addition, our deep sequencing analysis of 15 samples revealed that 17 of the 32 parallel mutations were already present at the beginning of the two epidemics, suggesting that fixation of these mutations may occur with different mechanisms, which may depend on the fitness gain provided by each mutation. This highlighted the difficulties in predicting the acquisition of mutations that can be correlated to viral adaptation to specific epidemiological conditions or to changes in virus virulence.     

Estimating the contribution of influenza to hospitalisations in New Zealand from 1994 to 2008

BackgroundInfluenza has a substantially but poorly measured impact on population health. Estimating its true contribution to hospitalisations remains a challenge.MethodsWe used simple and comprehensive negative binomial regression models with weekly counts of hospitalisations and isolates of influenza A, B and respiratory syncytial virus for the period 1994– 2008.ResultsThe estimated annual national average number of hospitalisations attributable to influenza was 822.1(95% CI: 815.3, 828.9) for pneumonia and influenza, 1861.3 (95% CI: 1842.9, 1879.7) for respiratory illness, 12.1 (95% CI: 2.6, 21.6) for circulatory illness, 2260.0 (95% CI: 2212.2, 2307.8) for all medical illness and 2419.9 (95% CI: 2356.4, 2483.4) for all causes. The contribution of influenza to total hospitalisations was about nine times larger than indicated by routine discharge data. New Zealanders 80 years of age and older had the highest annual excess rates of influenza-related hospitalisations (327.8 per 100,000); followed by infants under 1 year (244.5 per 100,000). Estimated influenza hospitalisation rates were also markedly higher in Pacific (83.3 per 100,000) and Māori (80.0 per 100,000) compared with European/Others (58.1 per 100,000).Respiratory illness was the major contributor to all cause hospitalisations attributed to influenza accounting for 77%. Influenza hospitalisations included only a negligible contribution from circulatory illness.ConclusionThese findings support efforts to reduce the impact of influenza, particularly for the most vulnerable population groups highlighted here. Analysis of the cost-effectiveness of such interventions needs to consider these higher modelled estimates of disease impact.     

Recent progress on the diagnosis of 2019 Novel Coronavirus

Coronavirus disease 2019 (COVID‐19) caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has become a global pandemic. Therefore, convenient, timely and accurate detection of SARS‐CoV‐2 is urgently needed. Here, we review the types, characteristics and shortcomings of various detection methods, as well as perspectives for the SARS‐CoV‐2 diagnosis. Clinically, nucleic acid‐based methods are sensitive but prone to false‐positive. The antibody‐based method has slightly lower sensitivity but higher accuracy. Therefore, it is suggested to combine the two methods to improve the detection accuracy of COVID‐19.     

Review of Budd-Chiari Syndrome

This study aims to report the Budd-Chiari syndrome clinical research status and progress that has occurred in over nearly 30 years in China, and emphasize the value of imaging in facilitating the diagnosis of Budd-Chiari syndrome based on more than 2500 cases. Findings on ultrasonography, computed tomography, magnetic resonance imaging, and digital subtraction angiography images are used to propose new Budd-Chiari syndrome types and subtypes. The new subtype classification presented here has important value for guiding interventional treatment. This study also proposes a new concept of anatomical and functional obstruction of hepatic vein that stresses the compensatory value of accessory hepatic vein and azygos vein and describes the risk of manipulation of the communication branch of inferior vena cava obstruction in interventional therapy.     

慢性乙型肝炎患者病毒复制与肝纤维化五项联合检测的临床应用

目的探讨慢性乙型肝炎患者乙型肝炎病毒(HBV)DNA复制与肝纤维化五项指标:透明质酸(HA)、Ⅲ型前胶原N端肽(PⅢPN)、Ⅳ型胶原(CⅣ)、层粘连蛋白(LN)、甘胆酸(CG)联合检测的临床意义。方法选取2018年7月至2019年9月在汉川市人民医院确诊的慢性乙型肝炎患者109例为研究对象,选取40例健康体检者为对照组,按HBV DNA的载量,将研究对象分为低载量组(104copy/mL)39例,中载量组[(104～106)copy/mL]33例,高载量组(106copy/mL)37例,对照组(500 copy/mL)40例。分别检测HBV DNA和肝纤维化五项,采用SPSS 19.0统计学软件对数据进行统计分析。结果低载量组和中载量组肝纤五项检测结果与对照组比较,差异无统计学意义(P0.05);高载量组肝纤五项检测结果与对照组比较,差异有统计学意义(P0.05)。随着HBV DNA载量的增加,肝纤五项各检测指标的数值也在增加。肝纤五项(HA、PⅢPN、CⅣ、LN、CG)的ROC曲线下面积(AUC)分别为0.556、0.763、0.742、0.420、0.695,其中PⅢPN的AUC最大,表明PⅢPN比其他指标对肝脏疾病的诊断准确率最高;LN的AUC最小,0.5,表明其单独诊断的准确率低。结论 HBV DNA载量与血清肝纤维化五项指标联合检测是慢性乙型肝炎患者病情监测的一个良好指标,临床应及时关注慢性乙型肝炎患者病毒复制与肝纤维化水平,延缓肝硬化的发生。     

Accelerated mass production of influenza virus seed stocks in HEK-293 suspension cell cultures by reverse genetics

Despite major advances in developing capacities and alternative technologies to egg-based production of influenza vaccines, responsiveness to an influenza pandemic threat is limited by the time it takes to generate a Candidate Vaccine Virus (CVV) as reported by the 2015 WHO Informal Consultation report titled “Influenza Vaccine Response during the Start of a Pandemic”.In previous work, we have shown that HEK-293 cell culture in suspension and serum free medium is an efficient production platform for cell culture manufacturing of influenza candidate vaccines. This report, took advantage of, recombinant DNA technology using Reverse Genetics of influenza strains, and advances in the large-scale transfection of suspension cultured HEK-293 cells. We demonstrate the efficient generation of H1N1 with the PR8 backbone reassortant under controlled bioreactor conditions in two sequential steps (transfection/rescue and infection/production). This approach could deliver a CVV for influenza vaccine manufacturing within two-weeks, starting from HA and NA pandemic sequences. Furthermore, the scalability of the transfection technology combined with the HEK-293 platform has been extensively demonstrated at >100 L scale for several biologics, including recombinant viruses.Thus, this innovative approach is better suited to rationally engineer and mass produce influenza CVV within significantly shorter timelines to enable an effective global response in pandemic situations.     

Enhancing viral vaccine production using engineered knockout vero cell lines – A second look

The global adoption of vaccines to combat disease is hampered by the high cost of vaccine manufacturing. The work described herein follows two previous publications (van der Sanden et al., 2016; Wu et al., 2017) that report a strategy to enhance poliovirus and rotavirus vaccine production through genetic modification of the Vero cell lines used in large-scale vaccine manufacturing. CRISPR/Cas9 gene editing tools were used to knockout Vero target genes previously shown to play a role in polio- and rotavirus production. Subsequently, small-scale models of current industry manufacturing systems were developed and adopted to assess the increases in polio- and rotavirus output by multiple stable knockout cell lines. Unlike previous studies, the Vero knockout cell lines failed to achieve desired target yield increases. These findings suggest that additional research will be required before implementing the genetically engineered Vero cell lines in the manufacturing process for polio- and rotavirus vaccines to be able to supply vaccines at reduced prices.