scholarly journals Study of Antibody-Dependent Reactions of Mast Cells In Vitro and in a Model of Severe Influenza Infection in Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrey Mamontov ◽  
Igor Losev ◽  
Dmitrii Korzhevskii ◽  
Valeriia Guselnikova ◽  
Alexander Polevshchikov ◽  
...  
Keyword(s):  
Mast Cells ◽  
Immune Complex ◽  
H5n1 Virus ◽  
Influenza Infection ◽  
Histamine Receptor ◽  
H1n1 Influenza ◽  
Influenza Viruses ◽  
Blue Staining ◽  
Receptor Blockers

We investigated the reaction of mouse peritoneal mast cells (MCs) in vitro after IgG-containing immune complex introduction using A/H5N1 and A/H1N1pdm09 influenza viruses as antigens. The sera of immune mice served as a source of IgG antibodies. The concentration of histamine in the supernatants was determined at 4 hours after incubation with antisera and virus. We compared the contribution of MCs to the pathogenesis of post-immunization influenza infection with A/H5N1 and A/H1N1 influenza viruses in mice. The mice were immunized parenterally with inactivated viruses and challenged with lethal doses of drift A/H5N1 and A/H1N1 influenza viruses on the 14th day after immunization. Simultaneously, half of the mice were injected intraperitoneally with a mixture of histamine receptor blockers (chloropyramine and quamatel). In in vitro experiments, the immune complex formed by A/H5N1 virus and antiserum caused a significant increase in the histamine release compared to immune serum or the virus alone. With regard to the A/H1N1 virus, such an increase was not significant. A/H1N1 immunization caused detectable HI response in mice at 12th day after immunization, in contrast to the A/H5N1 virus. After challenge of A/H5N1-immunized mice, administration of antihistamines increased the survival rate by up to 90%. When infecting the A/H1N1-immunized mice, 90% of the animals were already protected from lethal infection by day 14; the administration of histamine receptor blockers did not increase survival. Histological examination of the lungs has shown that toluidine blue staining allows to estimate the degree of MC degranulation. The possibility of in vitro activation of murine MCs by IgG-containing immune complexes has been shown. In a model of influenza infection, it was shown that the administration of histamine receptor blockers increased survival. When the protection was formed faster due to the earlier production of HI antibodies, the administration of histamine receptor blockers did not significantly affect the course of the infection. These data allow to propose that even if there are antibody-dependent MC reactions, they can be easily stopped by the administration of histamine receptor blockers.

scholarly journals In vitro and in vivo characterization of new swine-origin H1N1 influenza viruses

Nature ◽  
2009 ◽  
Vol 460 (7258) ◽  
pp. 1021-1025 ◽  
Author(s):  
Yasushi Itoh ◽  
Kyoko Shinya ◽  
Maki Kiso ◽  
Tokiko Watanabe ◽  
Yoshihiro Sakoda ◽  
...  
Keyword(s):  
H1n1 Influenza ◽  
Influenza Viruses ◽  
In Vivo Characterization

scholarly journals N-linked glycosylation plays an important role in budding of NA protein and virulence of influenza viruses

2020 ◽  
Author(s):  
Danqi Bao ◽  
Ruixue Xue ◽  
Min Zhang ◽  
Chenyang Lu ◽  
Tianxin Ma ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Replication ◽  
Immune Escape ◽  
H1n1 Influenza ◽  
Influenza Viruses ◽  
H1n1 Influenza Virus ◽  
Protein Loss ◽  
Knock Out

Neuraminidase (NA) has multiple functions in the life cycle of influenza virus, especially in the late stage of virus replication. Both of Hemagglutinin (HA) and NA are highly glycosylated proteins. N-linked glycosylation (NLG) of HA has been reported to contribute to immune escape and virulence of influenza viruses. However, the function of NLG of NA remains largely unclear. In this study, we found that NLG is critical for budding ability of NA. Tunicamycin treatment or NLG knock-out significantly inhibited the budding of NA. Further studies showed that the NLG knock-out caused attenuation of virus in vitro and in vivo. Notably the NLG at 219 position plays an important role in budding, replication, and virulence of H1N1 influenza virus. To explore the underlying mechanism, unfolded protein response (UPR) was determined in NLG knock-out NA overexpressed cells, which showed that the mutant NA was mainly located in ER, and the UPR markers BIP and p-eIF2α were upregulated, and XBP1 was downregulated. All the results indicated that NLG knock-out NA was stacked in ER and triggered UPR, which might shut down the budding process of NA. Overall, the study shed light on the function of NLG of NA in virus replication and budding. IMPORTANCE NA is a highly glycosylated protein. Nevertheless, how the NLG affects the function of NA protein remains largely unclear. In this study, we found that NLG plays important roles in budding and Neuraminidase activity of NA protein. Loss of NLG attenuated viral budding and replication. Especially the 219 NLG site mutation significantly attenuated the replication and virulence of H1N1 influenza virus in vitro and in vivo, which suggested that NLG of NA protein is a novel virulence marker for influenza viruses.

scholarly journals Tropism and Infectivity of a Seasonal A(H1N1) and a Highly Pathogenic Avian A(H5N1) Influenza Virus in Primary Differentiated Ferret Nasal Epithelial Cell Cultures

2019 ◽  
Vol 93 (10) ◽  
Author(s):  
Hui Zeng ◽  
Cynthia S. Goldsmith ◽  
Amrita Kumar ◽  
Jessica A. Belser ◽  
Xiangjie Sun ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Avian Influenza ◽  
H5n1 Virus ◽  
H1n1 Virus ◽  
Influenza Virus Infection ◽  
Influenza Viruses ◽  
Host Interactions ◽  
Culture Model

ABSTRACTFerrets represent an invaluable animal model to study influenza virus pathogenesis and transmission. To further characterize this model, we developed a differentiated primary ferret nasal epithelial cell (FNEC) culture model for investigation of influenza A virus infection and virus-host interactions. This well-differentiated culture consists of various cell types, a mucociliary clearance system, and tight junctions, representing the nasal ciliated pseudostratified respiratory epithelium. Both α2,6-linked and α2,3-linked sialic acid (SA) receptors, which preferentially bind the hemagglutinin (HA) of human and avian influenza viruses, respectively, were detected on the apical surface of the culture with different cellular tropisms. In accordance with the distribution of SA receptors, we observed that a pre-2009 seasonal A(H1N1) virus infected both ciliated and nonciliated cells, whereas a highly pathogenic avian influenza (HPAI) A(H5N1) virus primarily infected nonciliated cells. Transmission electron microscopy revealed that virions were released from or associated with the apical membranes of ciliated, nonciliated, and mucin-secretory goblet cells. Upon infection, the HPAI A(H5N1) virus replicated to titers higher than those of the human A(H1N1) virus at 37°C; however, replication of the A(H5N1) virus was significantly attenuated at 33°C. Furthermore, we found that infection with the A(H5N1) virus induced higher expression levels of immune mediator genes and resulted in more cell damage/loss than with the human A(H1N1) virus. This primary differentiated FNEC culture model, recapitulating the structure of the nasal epithelium, provides a useful model to bridgein vivoandin vitrostudies of cellular tropism, infectivity, and pathogenesis of influenza viruses during the initial stages of infection.IMPORTANCEAlthough ferrets serve as an important model of influenza virus infection, much remains unknown about virus-host interactions in this species at the cellular level. The development of differentiated primary cultures of ferret nasal epithelial cells is an important step toward understanding cellular tropism and the mechanisms of influenza virus infection and replication in the airway milieu of this model. Using lectin staining and microscopy techniques, we characterized the sialic acid receptor distribution and the cellular composition of the culture model. We then evaluated the replication of and immune response to human and avian influenza viruses at relevant physiological temperatures. Our findings offer significant insight into this first line of defense against influenza virus infection and provide a model for the evaluation of emerging influenza viruses in a well-controlledin vitroenvironmental setting.

scholarly journals Cross-Protection of Influenza A Virus Infection by a DNA Aptamer Targeting the PA Endonuclease Domain

2015 ◽  
Vol 59 (7) ◽  
pp. 4082-4093 ◽  
Author(s):  
Shuofeng Yuan ◽  
Naru Zhang ◽  
Kailash Singh ◽  
Huiping Shuai ◽  
Hin Chu ◽  
...  
Keyword(s):  
Virus Infection ◽  
Influenza A Virus ◽  
Influenza A ◽  
H5n1 Virus ◽  
Influenza Viruses ◽  
Cross Protection ◽  
Dna Aptamer ◽  
Endonuclease Activity ◽  
Endonuclease Domain

ABSTRACTAmino acid residues in the N-terminal of the PA subunit (PAN) of the influenza A virus polymerase play critical roles in endonuclease activity, protein stability, and viral RNA (vRNA) promoter binding. In addition, PANis highly conserved among different subtypes of influenza virus, which suggests PANto be a desired target in the development of anti-influenza agents. We selected DNA aptamers targeting the intact PA protein or the PANdomain of an H5N1 virus strain using systematic evolution of ligands by exponential enrichment (SELEX). The binding affinities of selected aptamers were measured, followed by an evaluation ofin vitroendonuclease inhibitory activity. Next, the antiviral effects of enriched aptamers against influenza A virus infections were examined. A total of three aptamers targeting PA and six aptamers targeting PANwere selected. Our data demonstrated that all three PA-selected aptamers neither inhibited endonuclease activity nor exhibited antiviral efficacy, whereas four of the six PAN-selected aptamers inhibited both endonuclease activity and H5N1 virus infection. Among the four effective aptamers, one exhibited cross-protection against infections of H1N1, H5N1, H7N7, and H7N9 influenza viruses, with a 50% inhibitory concentration (IC50) of around 10 nM. Notably, this aptamer was identified at the 5th round but disappeared after the 10th round of selection, suggesting that the identification and evaluation of aptamers at early rounds of selection may be highly helpful for screening effective aptamers. Overall, our study provides novel insights for screening and developing effective aptamers for use as anti-influenza drugs.

scholarly journals INFLUENZA : A COMPLETE OVERVIEW

2020 ◽  
pp. 1-5
Author(s):  
Venkata dinesh kumar kandula
Keyword(s):  
Hong Kong ◽  
20Th Century ◽  
Influenza A ◽  
H5n1 Virus ◽  
Influenza Infection ◽  
Influenza Viruses ◽  
Spanish Influenza ◽  
The World ◽  
Large Outbreak ◽  
Hpai H5n1

● At first haemophilus influenza was considered as the causative agent for influenza but after the research it has been found that it caused various other types of infections but not influenza. Influenza was caused by some flu virus which was first isolated from pigs in 1931 and from humans in 1933.(4) ● The 1918 influenza pandemic was the most severe pandemic in recent history it was caused by an H1N1 virus with the genes of avian origin although there is not universal consensus regarding where the virus originated it spread worldwide during 1918 and 1919. (3) ● It was first identified in military personnel in spring 1980 it is estimated that about 500 million people or one third of the world's population became infected with this virus.(3) ● The number of deaths was estimated to be at least 50 million worldwide with about 6,75,000 deaths occurring in the United States. (3) ● Mortality was high in people younger than five years old ,20 to 40 years old and in 65 years and older. The high mortality in healthy people including those in the 20 to 40 year age group was a unique feature of this pandemic. (3) ● There was no vaccine to protect against influenza infection and no antibiotics to treat secondary bacterial infections that can be associated with influenza infection control efforts worldwide were limited to non-pharmaceutical intervention such as isolation quarantine good personal hygiene use of disinfectants and limitations of public gathering which were applied unevenly.(3) ● In the northern and southern parts of the world outbreaks occur mainly in the winter while around the equator outbreaks may occur at any time of the year .In the northern and southern parts of the world outbreaks occur mainly in the winter while around the equator outbreaks may occur at any time of the year.(7) ● In the 20th century three influenza pandemics occurred Spanish influenza in 1918 where the death toll ranged from 17- 200 million deaths, Asian influenza in 1957- 2 million deaths and Hong Kong influenza in 1968 -1 million deaths. ● The world health organisation declared an outbreak of a new type of influenza A or H1N1 to be a pandemic in June 2009. ● influenza may also affect other animals including pig horses and birds.(9) ● The name “influenza” originated in 15th century Italy, from an epidemic attributed to “influence of the stars.” The first pandemic that fits the description of influenza was in 1580. At least four pandemics of influenza occurred in the 19th century, and three occurred in the 20th century. The pandemic of “Spanish” influenza in 1918–1919 caused an estimated 21 million deaths worldwide. The first pandemic of the 21st century occurred in 2009–2010. Historically, influenza viruses of three HA subtypes (H1, H2 and H3) have acquired the ability to be transmitted efficiently between humans. Currently, influenza viruses of the H1 and H3 subtype co-circulate in humans, however influenza viruses of the H2, H5, H6, H7 and H9 subtype are also considered to represent a pandemic threat. In 1997, a large outbreak of highly pathogenic avian influenza (HPAI) H5N1 virus in poultry in Hong Kong resulted in the first documented cases of direct transmission of HPAI H5N1 virus from poultry to humans, with a fatal outcome in 6 out of 18 cases [17]. As a result, this outbreak warranted the mass culling of 1.5 million chickens. In 2003, a large outbreak of an HPAI H7N7 virus in poultry in the Netherlands resulted in 89 cases of human infections, one of which was fatal [21]. HPAI H7N7 virus displayed an unusual tissue tropism; the virus targeted the conjunctiva, resulting in conjunctivitis, a symptom rarely reported for other influenza virus subtypes.(1)

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