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13 pages, 4735 KiB

Open AccessArticle

Tropism and Infectivity of Pandemic Influenza A H1N1/09 Virus in the Human Placenta

by Yan-Na Xiao, Fei-Yuan Yu, Qian Xu and Jiang Gu

Viruses 2022, 14(12), 2807; https://doi.org/10.3390/v14122807 - 15 Dec 2022

Cited by 2 | Viewed by 1385

Abstract

Influenza virus infection in pregnant women may put the fetus at higher risk; however, to date, there has been no detailed research about the expression of influenza virus receptors in the human placenta. We employed the lectin staining technique, which is a classic [...] Read more.

Influenza virus infection in pregnant women may put the fetus at higher risk; however, to date, there has been no detailed research about the expression of influenza virus receptors in the human placenta. We employed the lectin staining technique, which is a classic influenza virus receptor research method for studying the distribution of viral receptors in the human placenta. In addition, we examined the susceptibility of the human placenta to H1N1/09, by detecting viral proteins and RNA at different time points post-infection. We found that the human placenta expressed both avian and human influenza A virus receptors (α-2, 3-linked sialic acid and α-2, 6-linked sialic acid). In addition, H1N1/09 did not only infect the human placenta, but also replicated and was released into the culture media. We concluded that the human placenta is susceptible to the 2009 influenza A virus (H1N1/09) infection, and that particular attention should be paid to shielding pregnant women from infection during influenza season. Full article

(This article belongs to the Special Issue State-of-the-Art Influenza Virus Research in China)

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11 pages, 1995 KiB

Open AccessArticle

The Impact of Urbanization and Human Mobility on Seasonal Influenza in Northern China

by Jiao Yang, Xudong Guo, Ting Zhang, Qing Wang, Xingxing Zhang, Jin Yang, Shengjie Lai, Luzhao Feng and Weizhong Yang

Viruses 2022, 14(11), 2563; https://doi.org/10.3390/v14112563 - 19 Nov 2022

Cited by 4 | Viewed by 1847

Abstract

The intensity of influenza epidemics varies significantly from year to year among regions with similar climatic conditions and populations. However, the underlying mechanisms of the temporal and spatial variations remain unclear. We investigated the impact of urbanization and public transportation size on influenza [...] Read more.

The intensity of influenza epidemics varies significantly from year to year among regions with similar climatic conditions and populations. However, the underlying mechanisms of the temporal and spatial variations remain unclear. We investigated the impact of urbanization and public transportation size on influenza activity. We used 6-year weekly provincial-level surveillance data of influenza-like disease incidence (ILI) and viral activity in northern China. We derived the transmission potential of influenza for each epidemic season using the susceptible–exposed–infectious–removed–susceptible (SEIRS) model and estimated the transmissibility in the peak period via the instantaneous reproduction number (R_t). Public transport was found to explain approximately 28% of the variance in the seasonal transmission potential. Urbanization and public transportation size explained approximately 10% and 21% of the variance in maximum R_t in the peak period, respectively. For the mean R_t during the peak period, urbanization and public transportation accounted for 9% and 16% of the variance in R_t, respectively. Our results indicated that the differences in the intensity of influenza epidemics among the northern provinces of China were partially driven by urbanization and public transport size. These findings are beneficial for predicting influenza intensity and developing preparedness strategies for the early stages of epidemics. Full article

(This article belongs to the Special Issue State-of-the-Art Influenza Virus Research in China)

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12 pages, 2680 KiB

Open AccessCommunication

Incidence and Mortality Trends of Upper Respiratory Infections in China and Other Asian Countries from 1990 to 2019

by Qiao Liu, Chenyuan Qin, Min Du, Yaping Wang, Wenxin Yan, Min Liu and Jue Liu

Viruses 2022, 14(11), 2550; https://doi.org/10.3390/v14112550 - 18 Nov 2022

Cited by 3 | Viewed by 3580

Abstract

Respiratory infections remain a major public health problem, affecting people of all age groups, but there is still a lack of studies analyzing the burden of upper respiratory infections (URIs) in Asian countries. We used the data from the Global Burden of Diseases [...] Read more.

Respiratory infections remain a major public health problem, affecting people of all age groups, but there is still a lack of studies analyzing the burden of upper respiratory infections (URIs) in Asian countries. We used the data from the Global Burden of Diseases Study 2019 results to assess the current status and trends of URI burden from 1990 to 2019 in Asian countries. We found that Thailand had the highest age-standardized incidence rate (ASIR) of URI both in 1990 (354,857.14 per 100,000) and in 2019 (344,287.93 per 100,000); and the highest age-standardized mortality rate (ASMR) was in China in 1990 (2.377 per 100,000), and in Uzbekistan in 2019 (0.418 per 100,000). From 1990 to 2019, ASIRs of URI slightly increased in several countries, with the speediest in Pakistan (estimated annual percentage change [EAPC] = 0.404%, 95% CI, 0.322% to 0.486%); and Kuwait and Singapore had uptrends of ASMRs, at a speed of an average 3.332% (95% CI, 2.605% to 4.065%) and 3.160% (95% CI, 1.971% to 4.362%) per year, respectively. The age structure of URI was similar at national, Asian and Global levels. Children under the age of five had the highest incidence rate, and the elderly had the highest mortality rate of URI. Asian countries with a Socio-demographic Index between 0.5 and 0.7 had relatively lower ASIRs but higher ASMRs of URIs. The declined rate of URI ASMR in Asian countries was more pronounced in higher baseline (ASMR in 1990) countries. Our findings suggest that there was a huge burden of URI cases in Asia that affected vulnerable and impoverished people’s livelihoods. Continuous and high-quality surveillance data across Asian countries are needed to improve the estimation of the disease burden attributable to URIs, and the best public health interventions are needed to curb this burden. Full article

(This article belongs to the Special Issue State-of-the-Art Influenza Virus Research in China)

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11 pages, 2016 KiB

Open AccessArticle

Inter-Fighting between Influenza A Virus NS1 and β-TrCP: A Novel Mechanism of Anti-Influenza Virus

by Haiwei Sun, Kai Wang, Wei Yao, Jingyi Liu, Lu Lv, Xinjin Shi and Hongjun Chen

Viruses 2022, 14(11), 2426; https://doi.org/10.3390/v14112426 - 31 Oct 2022

Cited by 2 | Viewed by 1760

Abstract

Influenza A virus (IAV) prevents innate immune signaling during infection. In our previous study, the production of pro-inflammatory cytokines was associated with Cullin-1 RING ligase (CRL1), which was related to NF-κB activation. However, the underlying mechanism is unclear. Here, an E3 ligase, β-transducin [...] Read more.

Influenza A virus (IAV) prevents innate immune signaling during infection. In our previous study, the production of pro-inflammatory cytokines was associated with Cullin-1 RING ligase (CRL1), which was related to NF-κB activation. However, the underlying mechanism is unclear. Here, an E3 ligase, β-transducin repeat-containing protein (β-TrCP), was significantly downregulated during IAV infection. Co-IP analysis revealed that non-structural 1 protein (NS1) interacts with β-TrCP. With co-transfection, an increase in NS1 expression led to a reduction in β-TrCP expression, affecting the level of IκBα and then resulting in repression of the activation of the NF-κB pathway during IAV infection. In addition, β-TrCP targets the viral NS1 protein and significantly reduces the replication level of influenza virus. Our results provide a novel mechanism for influenza to modulate its immune response during infection, and β-TrCP may be a novel target for influenza virus antagonism. Full article

(This article belongs to the Special Issue State-of-the-Art Influenza Virus Research in China)

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13 pages, 2041 KiB

Open AccessArticle

H1N1 Influenza A Virus Protein NS2 Inhibits Innate Immune Response by Targeting IRF7

by Bo Zhang, Minxuan Liu, Jiaxin Huang, Qiaoying Zeng, Qiyun Zhu, Shuai Xu and Hualan Chen

Viruses 2022, 14(11), 2411; https://doi.org/10.3390/v14112411 - 31 Oct 2022

Cited by 8 | Viewed by 2142

Abstract

Influenza A virus (IAV) is a globally distributed zoonotic pathogen and causes a highly infectious respiratory disease with high morbidity and mortality in humans and animals. IAV has evolved various strategies to counteract the innate immune response, using different viral proteins. However, the [...] Read more.

Influenza A virus (IAV) is a globally distributed zoonotic pathogen and causes a highly infectious respiratory disease with high morbidity and mortality in humans and animals. IAV has evolved various strategies to counteract the innate immune response, using different viral proteins. However, the mechanisms are not fully elucidated. In this study, we demonstrated that the nonstructural protein 2 (NS2) of H1N1 IAV negatively regulate the induction of type-I interferon. Co-immunoprecipitation experiments revealed that NS2 specifically interacts with interferon regulatory factor 7 (IRF7). NS2 blocks the nuclear translocation of IRF7 by inhibiting the formation of IRF7 dimers, thereby prevents the activation of IRF7 and inhibits the production of interferon-beta. Taken together, these findings revealed a novel mechanism by which the NS2 of H1N1 IAV inhibits IRF7-mediated type-I interferon production. Full article

(This article belongs to the Special Issue State-of-the-Art Influenza Virus Research in China)

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13 pages, 1761 KiB

Open AccessArticle

Transmission Patterns of Seasonal Influenza in China between 2010 and 2018

by Hao Lei, Lei Yang, Gang Wang, Chi Zhang, Yuting Xin, Qianru Sun, Bing Zhang, Tao Chen, Jing Yang, Weijuan Huang, Modi Xu, Yu Xie, Yinghan Wang, Pei Xu, Litao Sun, Deyin Guo, Xiangjun Du, Dayan Wang and Yuelong Shu

Viruses 2022, 14(9), 2063; https://doi.org/10.3390/v14092063 - 17 Sep 2022

Cited by 8 | Viewed by 2699

Abstract

Background Understanding the transmission source, pattern, and mechanism of infectious diseases is essential for targeted prevention and control. Though it has been studied for many years, the detailed transmission patterns and drivers for the seasonal influenza epidemics in China remain elusive. Methods In [...] Read more.

Background Understanding the transmission source, pattern, and mechanism of infectious diseases is essential for targeted prevention and control. Though it has been studied for many years, the detailed transmission patterns and drivers for the seasonal influenza epidemics in China remain elusive. Methods In this study, utilizing a suite of epidemiological and genetic approaches, we analyzed the updated province-level weekly influenza surveillance, sequence, climate, and demographic data between 1 April 2010 and 31 March 2018 from continental China, to characterize detailed transmission patterns and explore the potential initiating region and drivers of the seasonal influenza epidemics in China. Results An annual cycle for influenza A(H1N1)pdm09 and B and a semi-annual cycle for influenza A(H3N2) were confirmed. Overall, the seasonal influenza A(H3N2) virus caused more infection in China and dominated the summer season in the south. The summer season epidemics in southern China were likely initiated in the “Lingnan” region, which includes the three most southern provinces of Hainan, Guangxi, and Guangdong. Additionally, the regions in the south play more important seeding roles in maintaining the circulation of seasonal influenza in China. Though intense human mobility plays a role in the province-level transmission of influenza epidemics on a temporal scale, climate factors drive the spread of influenza epidemics on both the spatial and temporal scales. Conclusion The surveillance of seasonal influenza in the south, especially the “Lingnan” region in the summer, should be strengthened. More broadly, both the socioeconomic and climate factors contribute to the transmission of seasonal influenza in China. The patterns and mechanisms revealed in this study shed light on the precise forecasting, prevention, and control of seasonal influenza in China and worldwide. Full article

(This article belongs to the Special Issue State-of-the-Art Influenza Virus Research in China)

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Review

Jump to: Research

21 pages, 1889 KiB

Open AccessReview

Influenza and Universal Vaccine Research in China

by Jiali Li, Yifan Zhang, Xinglong Zhang and Longding Liu

Viruses 2023, 15(1), 116; https://doi.org/10.3390/v15010116 - 30 Dec 2022

Cited by 20 | Viewed by 3327

Abstract

Influenza viruses usually cause seasonal influenza epidemics and influenza pandemics, resulting in acute respiratory illness and, in severe cases, multiple organ complications and even death, posing a serious global and human health burden. Compared with other countries, China has a large population base [...] Read more.

Influenza viruses usually cause seasonal influenza epidemics and influenza pandemics, resulting in acute respiratory illness and, in severe cases, multiple organ complications and even death, posing a serious global and human health burden. Compared with other countries, China has a large population base and a large number of influenza cases and deaths. Currently, influenza vaccination remains the most cost-effective and efficient way to prevent and control influenza, which can significantly reduce the risk of influenza virus infection and serious complications. The antigenicity of the influenza vaccine exhibits good protective efficacy when matched to the seasonal epidemic strain. However, when influenza viruses undergo rapid and sustained antigenic drift resulting in a mismatch between the vaccine strain and the epidemic strain, the protective effect is greatly reduced. As a result, the flu vaccine must be reformulated and readministered annually, causing a significant drain on human and financial resources. Therefore, the development of a universal influenza vaccine is necessary for the complete fight against the influenza virus. By statistically analyzing cases related to influenza virus infection and death in China in recent years, this paper describes the existing marketed vaccines, vaccine distribution and vaccination in China and summarizes the candidate immunogens designed based on the structure of influenza virus, hoping to provide ideas for the design and development of new influenza vaccines in the future. Full article

(This article belongs to the Special Issue State-of-the-Art Influenza Virus Research in China)

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15 pages, 611 KiB

Open AccessReview

Defective Interfering Particles of Influenza Virus and Their Characteristics, Impacts, and Use in Vaccines and Antiviral Strategies: A Systematic Review

by Min Wu, Entong Zhou, Rui Sheng, Xiaoshu Fu, Jiemin Li, Chunlai Jiang and Weiheng Su

Viruses 2022, 14(12), 2773; https://doi.org/10.3390/v14122773 - 12 Dec 2022

Cited by 5 | Viewed by 2716

Abstract

Defective interfering particles (DIPs) are particles containing defective viral genomes (DVGs) generated during viral replication. DIPs have been found in various RNA viruses, especially in influenza viruses. Evidence indicates that DIPs interfere with the replication and encapsulation of wild-type viruses, namely standard viruses [...] Read more.

Defective interfering particles (DIPs) are particles containing defective viral genomes (DVGs) generated during viral replication. DIPs have been found in various RNA viruses, especially in influenza viruses. Evidence indicates that DIPs interfere with the replication and encapsulation of wild-type viruses, namely standard viruses (STVs) that contain full-length viral genomes. DIPs may also activate the innate immune response by stimulating interferon synthesis. In this review, the underlying generation mechanisms and characteristics of influenza virus DIPs are summarized. We also discuss the potential impact of DIPs on the immunogenicity of live attenuated influenza vaccines (LAIVs) and development of influenza vaccines based on NS1 gene-defective DIPs. Finally, we review the antiviral strategies based on influenza virus DIPs that have been used against both influenza virus and SARS-CoV-2. This review provides systematic insights into the theory and application of influenza virus DIPs. Full article

(This article belongs to the Special Issue State-of-the-Art Influenza Virus Research in China)

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