Influenzavirus A
Influenzavirus B
Orthomyxoviridae
USSR
Bird Diseases
Influenza, Human
Influenzavirus C
Hemagglutination Inhibition Tests
Neuraminidase
Absence of SP-A modulates innate and adaptive defense responses to pulmonary influenza infection. (1/31)
Mice lacking surfactant protein SP-A [SP-A(-/-)] and wild type SP-A(+/+) mice were infected with influenza A virus (IAV) by intranasal instillation. Decreased clearance of IAV was observed in SP-A(-/-) mice and was associated with increased pulmonary inflammation. Treatment of SP-A(-/-) mice with exogenous SP-A enhanced viral clearance and decreased lung inflammation. Uptake of IAV by alveolar macrophages was similar in SP-A(-/-) and SP-A(+/+) mice. Myeloperoxidase activity was reduced in isolated bronchoalveolar lavage neutrophils from SP-A(-/-) mice. B lymphocytes and activated T lymphocytes were increased in the lung and spleen, whereas T helper (Th) 1 responses were increased [interferon-gamma, interleukin (IL)-2, and IgG(2a)] and Th2 responses were decreased (IL-4, and IL-10, and IgG(1)) in the lungs of SP-A(-/-) mice 7 days after IAV infection. In the absence of SP-A, impaired viral clearance was associated with increased lung inflammation, decreased neutrophil myeloperoxidase activity, and increased Th1 responses. Because the airway is the usual portal of entry for IAV and other respiratory pathogens, SP-A is likely to play a role in innate defense and adaptive immune responses to IAV. (+info)Genetic and antigenic analysis of the first A/New Caledonia/20/99-like H1N1 influenza isolates reported in the Americas. (2/31)
From February through May of 1999, 13 cases of Influenza A virus (FLUAV), type H1N1 were reported at a Department of Defense influenza surveillance sentinel site in Lima, Peru. Genetic and antigenic analysis by hemagglutination inhibition and direct nucleotide sequencing of the HA1 region of the hemagglutinin gene were performed on two isolates, A/Peru/1641/99 and A/Peru/1798/99. Both isolates were distinct from the Bayern/7/95-like viruses circulating in the Americas and closely related to a Beijing/262/95-like variant, A/New Caledonia/20/99. With the exception of travel-related cases, the detection of these isolates represents the first appearance of New Caledonia/20/99-like viruses in the Americas. Since the characterization of these Peru isolates, a number of New Caledonia/20/99-like viruses have been reported worldwide. For the 2000/01 and 2001/02 influenza seasons, the World Health Organization (WHO) has recommended the inclusion of A/New Caledonia/20/99 as the H1N1 vaccine component for both the southern and northern hemispheres. (+info)Accuracy and power of bayes prediction of amino acid sites under positive selection. (3/31)
Bayes prediction quantifies uncertainty by assigning posterior probabilities. It was used to identify amino acids in a protein under recurrent diversifying selection indicated by higher nonsynonymous (d(N)) than synonymous (d(S)) substitution rates or by omega = d(N)/d(S) > 1. Parameters were estimated by maximum likelihood under a codon substitution model that assumed several classes of sites with different omega ratios. The Bayes theorem was used to calculate the posterior probabilities of each site falling into these site classes. Here, we evaluate the performance of Bayes prediction of amino acids under positive selection by computer simulation. We measured the accuracy by the proportion of predicted sites that were truly under selection and the power by the proportion of true positively selected sites that were predicted by the method. The accuracy was slightly better for longer sequences, whereas the power was largely unaffected by the increase in sequence length. Both accuracy and power were higher for medium or highly diverged sequences than for similar sequences. We found that accuracy and power were unacceptably low when data contained only a few highly similar sequences. However, sampling a large number of lineages improved the performance substantially. Even for very similar sequences, accuracy and power can be high if over 100 taxa are used in the analysis. We make the following recommendations: (1) prediction of positive selection sites is not feasible for a few closely related sequences; (2) using a large number of lineages is the best way to improve the accuracy and power of the prediction; and (3) multiple models of heterogeneous selective pressures among sites should be applied in real data analysis. (+info)DNA vaccine expressing conserved influenza virus proteins protective against H5N1 challenge infection in mice. (4/31)
Influenza vaccination practice, which is based on neutralizing antibodies, requires being able to predict which viral strains will be circulating. If an unexpected strain, as in the 1997 H5N1 Hong Kong outbreak, or even a pandemic emerges, appropriate vaccines may take too long to prepare. Therefore, strategies based on conserved influenza antigens should be explored. We studied DNA vaccination in mice with plasmids expressing conserved nucleoprotein (NP) and matrix (M) from an H1N1 virus. After vaccination, mice were challenged with A/H5N1 viruses of low, intermediate, and high lethality. A/NP+A/M DNA vaccination reduced replication of A/Hong Kong/486/97 (HK/486), a nonlethal H5N1 strain, and protected against lethal challenge with more virulent A/Hong Kong/156/97 (HK/156). After HK/156 exposure, mice survived rechallenge with A/Hong Kong/483/97 (HK/483), although the DNA vaccination alone protected poorly against this highly virulent strain. In the absence of antigenically matched hemagglutinin-based vaccines, DNA vaccination with conserved influenza genes may provide a useful first line of defense against a rapidly spreading pandemic virus. (+info)Production and characterization of a human recombinant monoclonal Fab fragment specific for influenza A viruses. (5/31)
A human recombinant monoclonal Fab fragment that specifically recognizes all the influenza A virus strains tested was produced in transformed Escherichia coli using the phage display technique. No strain of influenza B virus reacted with it. It was purified after four cycles of panning and by a single passage through an immunoaffinity column. About 1 mg of pure monoclonal antibody was obtained from 1 liter of culture medium in 3 working days. The Fab fragment reacted with a viral 27-kDa protein, which could reasonably be a matrix protein. Indirect immunofluorescence tests performed on virus-infected MDCK cells showed that this Fab fragment was at least equally efficient as other commercial monoclonal antibody-based systems in detecting influenza A viral infections. The potential advantages of human recombinant Fabs on murine monoclonal antibodies are discussed. (+info)Predominant contribution of IFN-beta expression to apoptosis induction in human uterine cervical fibroblast cells by influenza-virus infection. (6/31)
We have been investigating an apoptosis induction in human fetal membrane cells by influenza virus (IV) infection and the contribution of apoptosis induction to the viral infection-defense response between a fetus and the maternal body. For studying any role of uterine cells in the anti-viral response, we investigated the molecular mechanism of the apoptotic induction in human uterine cervical fibroblast cell line (HCF) by IV infection. IV type A and B infection induced DNA fragmentation in HCF. In IV-infected HCF, gene mRNA expression levels of interleukine (IL)-1beta, IL-6, tumor necrosis factor (TNF) alpha, Fas ligand, interferon regulatory factor (IRF)-1, interferon (IFN) alpha and IFN beta increased as compared with those in mock treatment cells, and the induction of mRNAs for double stranded RNA dependent protein kinase (PKR), indolamine 2,3-deoxygenase (IDO) and 2'-5' oligoadenylate synthetase (2-5 OAS) were indicated, which had a role for a host defense response induced by IFN-beta. The amount of IFN-beta protein increased by IV-infection, and DNA fragmentation was inhibited with anti-IFN-beta antibody and PKR inhibitor (2-aminopurine). Furthermore, a synthetic double stranded RNA, poly I : C, could induce almost the same phenomena as that induced by virus infection. We conclude that IV-infection induces the apoptosis in HCF cells through the IFN-beta expression regulated by double stranded RNA and IRF-1 induction, and suggest that the IFN-beta induction may be the predominant contribution to the IV infection induced HCF apoptosis. (+info)In vivo antiviral activity: defective interfering virus protects better against virulent Influenza A virus than avirulent virus. (7/31)
A defective interfering (DI) virus differs from the infectious virus from which it originated in having at least one major deletion in its genome. Such DI genomes are replicated only in cells infected in trans with homologous infectious virus and, as their name implies, they interfere with infectious virus replication and reduce the yield of progeny virus. This potent antiviral activity has been abundantly demonstrated in cell culture with many different DI animal viruses, but few in vivo examples have been reported, with the notable exception of DI Influenza A virus. A clue to this general lack of success arose recently when an anomaly was discovered in which DI Influenza A virus solidly protected mice from lethal disease caused by A/PR/8/34 (H1N1) and A/WSN/40 (H1N1) viruses, but protected only marginally from disease caused by A/Japan/305/57 (A/Jap, H2N2). The problem was not any incompatibility between the DI and infectious genomes, as A/Jap replicated the DI RNA in vivo. However, A/Jap required 300-fold more mouse infectious units to cause clinical disease than A/PR8 and it was hypothesized that it was this excess of infectivity that abrogated the protective activity of the DI virus. This conclusion was verified by varying the proportions of DI and challenge virus and showing that increasing the DI virus : infectious virus ratio in infected mice resulted in interference. Thus, counter-intuitively, DI virus is most effective against viruses that cause disease with low numbers of particles, i.e. virulent viruses. (+info)Avian influenza virus exhibits rapid evolutionary dynamics. (8/31)
Influenza A viruses from wild aquatic birds, their natural reservoir species, are thought to have reached a form of stasis, characterized by low rates of evolutionary change. We tested this hypothesis by estimating rates of nucleotide substitution in a diverse array of avian influenza viruses (AIV) and allowing for rate variation among lineages. The rates observed were extremely high, at >10(-3) substitutions per site, per year, with little difference among wild and domestic host species or viral subtypes and were similar to those seen in mammalian influenza A viruses. Influenza A virus therefore exhibits rapid evolutionary dynamics across its host range, consistent with a high background mutation rate and rapid replication. Using the same approach, we also estimated that the common ancestors of the hemagglutinin and neuraminidase sequences of AIV arose within the last 3,000 years, with most intrasubtype diversity emerging within the last 100 years and suggestive of a continual selective turnover. (+info)Influenza A Virus: According to the World Health Organization (WHO), Influenza A virus is an orthomyxovirus that causes respiratory illness in humans and many other animal species. It can be found in birds, pigs, horses, and humans. The viral genome consists of eight single-stranded RNA segments enclosed within a lipid membrane derived from the host cell. Two surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), are used to classify Influenza A virus into subtypes based on antigenic properties. There are 18 different HA subtypes and 11 NA subtypes, but only H1N1, H2N2, and H3N2 have caused widespread human disease since the 1900s.
Influenza A viruses can be further divided into strains based on differences in their internal proteins. The most common cause of seasonal flu epidemics in humans is Influenza A (H3N2) and Influenza A (H1N1) pdm09, the latter of which caused the 2009 pandemic. Wild aquatic birds are the natural hosts for a large variety of influenza A viruses, and they are also responsible for the emergence of new subtypes.
These viruses can occasionally cause outbreaks in domestic poultry and, more rarely, in humans. Avian influenza A (H5N1), avian influenza A (H7N9), and avian influenza A (H1N1) are some examples of zoonotic influenza viruses that have caused severe disease and death in humans. However, sustained human-to-human transmission has not been observed with these subtypes, except for the 2009 H1N1 pandemic strain, which was a reassortant virus containing genes from both avian and swine influenza A viruses.
Influenza Virus B is one of the two primary types of influenza viruses that cause seasonal flu in humans, with Influenza A being the other.
Influenza Virus B primarily infects humans and is generally associated with less severe illness compared to Influenza A. However, it can still cause significant respiratory disease, hospitalizations, and deaths, particularly among high-risk populations such as young children, older adults, pregnant women, and people with certain underlying medical conditions.
Influenza Virus B has only one known host - humans, while Influenza A can infect a variety of animals, including birds, pigs, and horses, making it more prone to mutations and the emergence of new strains.
Like Influenza A, Influenza Virus B also undergoes genetic changes over time, leading to the need for regular updates to the seasonal flu vaccine to ensure that it provides protection against the circulating strains.
Orthomyxoviridae is a family of viruses that includes influenza A, B, and C viruses, which are the causative agents of flu in humans and animals. These viruses are enveloped, meaning they have a lipid membrane derived from the host cell, and have a single-stranded, negative-sense RNA genome. The genome is segmented, meaning it consists of several separate pieces of RNA, which allows for genetic reassortment or "shuffling" when two different strains infect the same cell, leading to the emergence of new strains.
The viral envelope contains two major glycoproteins: hemagglutinin (HA) and neuraminidase (NA). The HA protein is responsible for binding to host cells and facilitating entry into the cell, while NA helps release newly formed virus particles from infected cells by cleaving sialic acid residues on the host cell surface.
Orthomyxoviruses are known to cause respiratory infections in humans and animals, with influenza A viruses being the most virulent and capable of causing pandemics. Influenza B viruses typically cause less severe illness and are primarily found in humans, while influenza C viruses generally cause mild upper respiratory symptoms and are also mainly restricted to humans.
I'm sorry for any confusion, but the abbreviation "USSR" stands for the Union of Soviet Socialist Republics, which was a socialist state in Eastern Europe and northern and central Asia that existed from 1922 until its dissolution in 1991. It was not a medical term or concept. If you have any questions related to medicine, I would be happy to try to help answer them for you.
'Bird diseases' is a broad term that refers to the various medical conditions and infections that can affect avian species. These diseases can be caused by bacteria, viruses, fungi, parasites, or toxic substances and can affect pet birds, wild birds, and poultry. Some common bird diseases include:
1. Avian influenza (bird flu) - a viral infection that can cause respiratory symptoms, decreased appetite, and sudden death in birds.
2. Psittacosis (parrot fever) - a bacterial infection that can cause respiratory symptoms, fever, and lethargy in birds and humans who come into contact with them.
3. Aspergillosis - a fungal infection that can cause respiratory symptoms and weight loss in birds.
4. Candidiasis (thrush) - a fungal infection that can affect the mouth, crop, and other parts of the digestive system in birds.
5. Newcastle disease - a viral infection that can cause respiratory symptoms, neurological signs, and decreased egg production in birds.
6. Salmonellosis - a bacterial infection that can cause diarrhea, lethargy, and decreased appetite in birds and humans who come into contact with them.
7. Trichomoniasis - a parasitic infection that can affect the mouth, crop, and digestive system in birds.
8. Chlamydiosis (psittacosis) - a bacterial infection that can cause respiratory symptoms, lethargy, and decreased appetite in birds and humans who come into contact with them.
9. Coccidiosis - a parasitic infection that can affect the digestive system in birds.
10. Mycobacteriosis (avian tuberculosis) - a bacterial infection that can cause chronic weight loss, respiratory symptoms, and skin lesions in birds.
It is important to note that some bird diseases can be transmitted to humans and other animals, so it is essential to practice good hygiene when handling birds or their droppings. If you suspect your bird may be sick, it is best to consult with a veterinarian who specializes in avian medicine.
Influenza, also known as the flu, is a highly contagious viral infection that attacks the respiratory system of humans. It is caused by influenza viruses A, B, or C and is characterized by the sudden onset of fever, chills, headache, muscle pain, sore throat, cough, runny nose, and fatigue. Influenza can lead to complications such as pneumonia, bronchitis, and ear infections, and can be particularly dangerous for young children, older adults, pregnant women, and people with weakened immune systems or chronic medical conditions. The virus is spread through respiratory droplets produced when an infected person coughs, sneezes, or talks, and can also survive on surfaces for a period of time. Influenza viruses are constantly changing, which makes it necessary to get vaccinated annually to protect against the most recent and prevalent strains.
Serologic tests are laboratory tests that detect the presence or absence of antibodies or antigens in a patient's serum (the clear liquid that separates from clotted blood). These tests are commonly used to diagnose infectious diseases, as well as autoimmune disorders and other medical conditions.
In serologic testing for infectious diseases, a sample of the patient's blood is collected and allowed to clot. The serum is then separated from the clot and tested for the presence of antibodies that the body has produced in response to an infection. The test may be used to identify the specific type of infection or to determine whether the infection is active or has resolved.
Serologic tests can also be used to diagnose autoimmune disorders, such as rheumatoid arthritis and lupus, by detecting the presence of antibodies that are directed against the body's own tissues. These tests can help doctors confirm a diagnosis and monitor the progression of the disease.
It is important to note that serologic tests are not always 100% accurate and may produce false positive or false negative results. Therefore, they should be interpreted in conjunction with other clinical findings and laboratory test results.
Influenza Virus C is a type of influenza virus that causes respiratory illness in humans. It is one of the three types of influenza viruses, along with Influenza A and Influenza B, that are known to infect humans. However, Influenza Virus C is much less common than Influenza A and B and typically causes milder symptoms.
Influenza Virus C is an enveloped, negative-sense, single-stranded RNA virus that belongs to the family Orthomyxoviridae. It has a distinct antigenic structure from Influenza A and B viruses and is not typically associated with large outbreaks or epidemics.
Infection with Influenza Virus C can cause respiratory symptoms such as cough, sore throat, and fever. However, it is not known to cause severe illness or death in otherwise healthy individuals. Antiviral medications are generally not recommended for treatment of Influenza Virus C infections, but supportive care such as rest, hydration, and fever reduction can help alleviate symptoms.
It's worth noting that most people develop immunity to Influenza Virus C after infection, which provides protection against future infections with the same strain. However, new strains of Influenza Virus C can emerge over time, which may require updated vaccines to provide adequate protection.
Hemagglutination inhibition (HI) tests are a type of serological assay used in medical laboratories to detect and measure the amount of antibodies present in a patient's serum. These tests are commonly used to diagnose viral infections, such as influenza or HIV, by identifying the presence of antibodies that bind to specific viral antigens and prevent hemagglutination (the agglutination or clumping together of red blood cells).
In an HI test, a small amount of the patient's serum is mixed with a known quantity of the viral antigen, which has been treated to attach to red blood cells. If the patient's serum contains antibodies that bind to the viral antigen, they will prevent the antigen from attaching to the red blood cells and inhibit hemagglutination. The degree of hemagglutination inhibition can be measured and used to estimate the amount of antibody present in the patient's serum.
HI tests are relatively simple and inexpensive to perform, but they have some limitations. For example, they may not detect early-stage infections before the body has had a chance to produce antibodies, and they may not be able to distinguish between different strains of the same virus. Nonetheless, HI tests remain an important tool for diagnosing viral infections and monitoring immune responses to vaccination or infection.
Neuraminidase is an enzyme that occurs on the surface of influenza viruses. It plays a crucial role in the life cycle of the virus by helping it to infect host cells and to spread from cell to cell within the body. Neuraminidase works by cleaving sialic acid residues from glycoproteins, allowing the virus to detach from infected cells and to move through mucus and other bodily fluids. This enzyme is a major target of antiviral drugs used to treat influenza, such as oseltamivir (Tamiflu) and zanamivir (Relenza). Inhibiting the activity of neuraminidase can help to prevent the spread of the virus within the body and reduce the severity of symptoms.
An antigen is any substance that can stimulate an immune response, particularly the production of antibodies. Viral antigens are antigens that are found on or produced by viruses. They can be proteins, glycoproteins, or carbohydrates present on the surface or inside the viral particle.
Viral antigens play a crucial role in the immune system's recognition and response to viral infections. When a virus infects a host cell, it may display its antigens on the surface of the infected cell. This allows the immune system to recognize and target the infected cells for destruction, thereby limiting the spread of the virus.
Viral antigens are also important targets for vaccines. Vaccines typically work by introducing a harmless form of a viral antigen to the body, which then stimulates the production of antibodies and memory T-cells that can recognize and respond quickly and effectively to future infections with the actual virus.
It's worth noting that different types of viruses have different antigens, and these antigens can vary between strains of the same virus. This is why there are often different vaccines available for different viral diseases, and why flu vaccines need to be updated every year to account for changes in the circulating influenza virus strains.
Influenza virus pseudoknot
Influenza Virus Testing Methods | CDC
Influenza Virus (Flu)
New Flu Virus Found in Bats | Influenza Virus | Live Science
Influenza virus vaccine, h5n1 (Audenz) Use During Pregnancy
New compound inhibits influenza virus replication - University of Bonn
Influenza Virus Icon Images
Innate lymphoid cells promote lung-tissue homeostasis after infection with influenza virus
Animal Influenza Virus Characterization and Analyses | Cornell University College of Veterinary Medicine
Molecular basis of host-adaptation interactions between influenza virus polymerase PB2 subunit and ANP32A | Nature...
Influenza Virus Vaccine (Intradermal Route, Intramuscular Route) Description and Brand Names - Mayo Clinic
Face masks to prevent transmission of influenza virus: a systematic review | Epidemiology & Infection | Cambridge Core
The Immunopathogenesis of Avian Influenza Virus in Avian Species | National Agricultural Library
3D Influenza virus | Difference Between
Edvotek Detection of the Influenza Virus Experiment Kit Detection of the
| Fisher Scientific
GHO | Global Health Observatory Data Repository (South-East Asia Region) | Influenza virus detections, latest week - Data
...
Frontiers | Immune Responses of Chickens Infected with Wild Bird-Origin H5N6 Avian Influenza Virus
Influenza Virus - Sugar Interactions, From Glycan Arrays To Better Vaccines | Sugar-Enable | Project | Fact sheet | H2020 |...
Corona Virus: Read Guava Leaf And Influenza Virus. - Health - Nigeria
New compound probably effectual against avian influenza virus - Health Jockey
The A, B, and C of influenza virus | Virology Blog
Breaking News English ESL Lesson Plan on Influenza Virus
Avian influenza virus in the aquatic environment: Surveillance in waterfowl habitat on the Delmarva Peninsula. | U.S....
Microtubules in Influenza Virus Entry and Egress<...
Generation of Escape Variants of Neutralizing Influenza Virus Monoclonal Antibodies | Protocol (Translated to French)