Order Articulavirales
Paul Pumpens, Peter Pushko, Philippe Le Mercier in Virus-Like Particles, 2022
The order is of extremely high medical importance, because of the continuous healthcare concern associated with influenza infections. There are four types of influenza virus, namely types A, B, C, and D belonging to the genera Alphainfluenzavirus, Betainfluenzavirus, Gammainfluenzavirus, and Deltainfluenzavirus, respectively. The influenza A and B viruses are clinically relevant for humans. Influenza A viruses are responsible for annual epidemics and all known influenza pandemics. The influenza B virus is primarily a human pathogen, which is not associated with an animal reservoir. It causes similar symptoms and disease as the influenza A virus. However, the frequency of the severe cases of influenza B infections appears to be significantly lower than that of influenza A. As to the influenza C, well-defined outbreaks have rarely been detected in humans, and the virus is rarely associated with severe syndromes. Most people have antibody to the influenza C virus by early adulthood, and influenza C is not included in the current influenza vaccine formulations. For more information and references, reviews of Pushko et al. (2008), Pushko and Tumpey (2015), and Pushko and Tretyakova (2020) are recommended.
Severe Influenza Pneumonia and Its Mimics in the Critical Care Unit
Cheston B. Cunha, Burke A. Cunha in Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
Influenza A virus is considered a self-limited infection. However, a patient with an ILI can be subjected to severe pneumonia with respiratory failure. Influenza A mainly targets the lower respiratory tract but might present with other distinct clinical syndromic entities in the CCU. Among them, multi-organ failure with ARDS and septic shock are the most prominent. The consideration about the different infectious and non-infectious conditions that mimic influenza pneumonia at admittance must be sufficient. A history of travel and exposures at the earliest possible entry point is essential. In addition, the absence of symptoms of ILIs does not effectively rule out influenza infection, especially in the elderly and immunocompromised people. Knowing the wide spectrum of the presentation and severity of influenza infection, intensivists in the CCU will have to find what they seek to.
Influenza virus
Peter M. Lydyard, Michael F. Cole, John Holton, William L. Irving, Nino Porakishvili, Pradhib Venkatesan, Katherine N. Ward in Case Studies in Infectious Disease, 2010
Direct transfer of an avian influenza A virus into humans. This process is undoubtedly happening at the moment, with an increasing number of human infections with the avian H5N1 virus (responsible for large avian epidemics, particularly among chickens) being reported worldwide. However, virus that crosses a species barrier in this way is often not well adjusted for replication in its new host. Currently, avian H5N1 virus does not replicate to high titer within infected humans. Person to person spread is therefore very inefficient, as infected individuals are not releasing large amounts of virus in their respiratory secretions. H5N1 virus has thus not emerged (yet) as a new human pandemic virus. There is a worry, however, that as it replicates within human cells, this virus may acquire mutations that could result in adaptation to efficient replication within human cells, at which point person to person spread will become more likely, and a true pandemic might eventuate. There is some evidence that the H1N1 virus that caused the 1918–19 pandemic was entirely avian in origin, and that it had been causing sporadic infections within humans for several years before its emergence as a pandemic virus in 1918. The presumption is that during those preceding years the virus acquired the necessary mutations to allow adaptation to increased replication within human cells.
Emerging antiviral therapies and drugs for the treatment of influenza
Published in Expert Opinion on Emerging Drugs, 2022
Jinshen Wang, Yihang Sun, Shuwen Liu
Influenza is an acute respiratory infectious disease caused by influenza viruses divided into four types: A, B, C and D. Indeed, due to antigenic transformation and drift, influenza A virus (IAVs) possesses the strongest infectivity and the highest mortality rate. Unlike IAVs, influenza B viruses mutate less, causing seasonal epidemics but rarely pandemics. Influenza C and D viruses are highly antigenically stable and only lead to mild upper respiratory tract infections. According to the antigenic features of two glycoproteins on the virus surface, including hemagglutinin (HA) and neuraminidase (NA), IAVs can be divided into 18 subtypes of HA (H1–H18) and 10 subtypes of NA (N1–N10) [1,2]. There have been four influenza outbreaks in human history. The first pandemic (Spanish influenza 1918–1919) caused by the H1N1 virus was responsible for 50 to 100 million deaths [3,4]. The ‘Asian flu’ caused by the H2N2 virus in 1957–1959 appeared in China and then spread to more than 20 countries worldwide, resulting in about 45 million infections and 1.1 million deaths [5,6]. In 1968–1969, the H3N2 virus replaced the H2N2 virus causing the Hong Kong pandemic, leading to approximately 1 million deaths [7,8]. In 2009, the swine-derived H1N1 virus spread to more than 30 countries worldwide through human-to-human transmission, which caused about 19,000 deaths and posed a huge threat to global public health security [8,9]. It is worth noting that since 1997, several avian influenza viruses have exhibited cross-species transmission and spread to humans, such as H5N1 and H7N9 [10–13].
The roles of epidermal growth factor receptor in viral infections
Published in Growth Factors, 2022
Influenza A virus (IAV) is the most virulent type of influenza virus that causes seasonal epidemics as well as global pandemics. It is made up of eight negative sense, single stranded RNA segments that are surrounded by viral envelope (Samji 2009). Eierhoff et al. (2010) have reported that EGFR promotes internalisation of IAV into host cells via both clathrin- and caveolin-1 dependent endocytosis. They have demonstrated that modulations of expression and activity of EGFR using siRNA and PD153035 in the early stage of infection alter the virus uptake and progeny virion production. Their studies also suggested that IAV attachment causes clustering of lipid-rafts which brings EGFR and other RTKs in close proximity. EGFR is activated in response to the clustering and facilitates the viral endocytosis (Figure 2(i)) (Eierhoff et al. 2010).
Hepatitis A virus structural protein pX interacts with ALIX and promotes the secretion of virions and foreign proteins through exosome-like vesicles
Published in Journal of Extracellular Vesicles, 2020
Wang Jiang, Pengjuan Ma, Libin Deng, Zhi Liu, Xu Wang, Xiyu Liu, Gang Long
HAV infection produces heterogeneous viral particles such as full particles containing the genomic RNA and empty particles absent of viral RNA [29]. Un-cleaved VP0 is only present in HAV empty particles, while in HAV full particles VP0 is at least partially cleaved [11,30]. Consistent with this, our data (Figure 6 and supplementary Figure 5) showed that the VP0-enriched fraction does not co-float with genomic RNA-enriched fraction, while mature VP2 was positively correlated with RNA. Removal of C-terminal half part of pX did not ablate the release of HAV empty particles which did not co-float with CD63 and ALIX. Following study will be required to reveal the cellular machinery governing the production of this population. HAV empty particles had been detected in the stool of infected patients about 50 years ago [31], and its biological significance remains unclear. Interestingly, functional significance of virus heterogeneous assembly received growing attention. Independent from infectious HCV lipoviral particles, HCV E2 was released on exosome-like vesicles which assist HCV infection through absorbing neutralizing antibody [32]. Morphological and compositional heterogeneity of Influenza A virus serves as a determinant of viral escape strategy in response to the antivirals [33].
Related Knowledge Centers
- Avian Influenza
- Hemagglutinin
- Orthomyxoviridae
- Protein
- Influenza
- Pathogen
- Pandemic
- Rna Virus
- Fi6
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