What is Influenza
Influenza (flu) is a respiratory infection in mammals and birds. It is caused by an RNA virus in the family Orthomyxoviridae.
The most common symptoms of the disease are chills, fever, sore throat, muscle pains, severe headache, coughing, weakness/fatigue and general discomfort. Sore throat, fever and coughs are the most frequent symptoms. In more serious cases, influenza causes pneumonia, which can be fatal, particularly for the young and the elderly. Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a more severe disease than the common cold and is caused by a different type of virus. Influenza may produce nausea and vomiting, particularly in children,
Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans.
Often, these new strains appear when an existing flu virus spreads to humans from other animal species, or when an existing human strain picks up new genes from a virus that usually infects birds or pigs. An avian strain named H5N1 raised the concern of a new influenza pandemic, after it emerged in Asia in the 1990s, but it has not evolved to a form that spreads easily between people. In April 2009 a novel flu strain evolved that combined genes from human, pig, and bird flu, initially dubbed "swine flu" and also known as influenza A/H1N1, emerged in Mexico, the United States, and several other nations.
Types of Influenza
The virus that caused Influenza is divided into three main types, Influenza A, Influenza B, and Influenza C. Influenza virus type A is found in a wide variety of bird and mammal species and can undergo major shifts in immunological properties. Influenza B is largely confined to humans and is an important cause of morbidity, which became unexpectedly prevalent in humans during 2000-2002. Influenza C infects humans, dogs and pigs and generally causes only mild upper respiratory tract infection.
However, influenza A and B viruses cause a wide spectrum of severe disease including lower respiratory, tract infection, pneumonia and encephalitis. Influenza A is further divided into subtypes based on antigenic differences in the membrane proteins hemagglutinin (HA) and neuraminidase (NA). 16 HAs (H1-H16) and 9 NA (N1-N9) had been identified. While different combinations of the two antigens appear more frequently in some groups of birds than others, only few subtypes have established themselves in humans (HA: H1, H2, and H3; NA: N1 and N2).
Influenza Hemagglutinin (HA) protein & antibody by Subtype:
| H1N1 | H1N2 | H1N3 | H2N2 | H3N2 |
| H4N4 | H4N6 | H4N8 | H5N1 | H5N2 |
| H5N3 | H5N8 | H6N1 | H6N4 | H7N7 |
| H8N4 | H9N2 | H10N3 | H10N9 | H11N2 |
| H11N9 | H12N1 | H12N5 | H13N8 | H15N8 |
| H16N3 | Influenza B |
ELISA for diagnosis of Influenza
(1)Influenza antibody
Influenza antibody and influenza antibodies are very important research tools for influenza diagnosis, influenza vaccine development, and anti-influenza virus therapy development. Monoclonal or polyclonal antibody can be raised with protein based antigen or peptide based antigen. Antibody raised with protein based antigen could have better specificity and/or binding affinity than antibody raised with peptide based antigen, but the cost is usually higher.
Anti influenza virus hemagglutinin (HA) monoclonal antibody or polyclonal antibody can be used for ELISA, western blotting detection, Immunohistochemistry (IHC), flow cytometry, neutralization assay, hemagglutinin inhibition assay, and early diagnosis of influenza viral infection.
Influenza Antibodies by Subtype：
| H1N1 Antibody | H1N2 Antibody | H1N3 Antibody | H2N2 Antibody | H3N2 Antibody |
| H4N4 Antibody | H4N6 Antibody | H4N8 Antibody | H5N1 Antibody | H5N2 Antibody |
| H5N3 Antibody | H5N8 Antibody | H6N1 Antibody | H6N4 Antibody | H7N7 Antibody |
| H8N4 Antibody | H9N2 Antibody | H10N3 Antibody | H10N9 Antibody | H11N2 Antibody |
| H11N9 Antibody | H12N1 Antibody | H12N5 Antibody | H13N8 Antibody | H15N8 Antibody |
| H16N3 Antibody | Influenza B Antibody |
(2)Influenza ELISA kit
Take H1N1 (Swine Flu 2009) Hemagglutinin ELISA kit and Hemagglutinin ELISA kit for instance.
The H1N1 (Swine Flu 2009) Hemagglutinin ELISA kit is the first swine flu 2009 testing kit in the world. It specifically tests swine influenza 2009 H1N1 hemagglutinin, but has no cross-reactivity with seasonal flu H1N1 hemagglutinin.
H5N1 (Avian Flu) Hemagglutinin ELISA kit is for the quantitative determination of hemagglutinin. The common influenza ELISA kits are solid phase sandwich ELISA ( Enzyme-Link Immunosorbent Assay), which are to be used for the in-vitro quantitative determination of hemagglutinin with high sensitivity and specificity. A monoclonal antibody specific for hemagglutinin has been coated onto a 96-well plate. Standards and samples are added to the wells, and any hemagglutinin present binds to the immobilized antibody.
The wells are washed and a horseradish peroxidase conjugated rabbit anti- hemagglutinin polyclonal antibody is then added, producing an antibody-antigen-antibody "sandwich". The wells are again washed and TMB substrate solution is loaded, which produces color in proportion to the amount of hemagglutinin present in the sample. To end the enzyme reaction, the stop solution is added and absorbances of the microwell are read at 450 nm.