directly hits 8 respiratory viruses, which can cause symptoms such as bronchitis , pneumonia, etc.!
viruses, non-cytological microorganisms, are extremely small, and can pass through bacterial filters. They are a group of nucleic acid genomes of DNA or RNA that need to be seen with an electron microscope. According to the transmission routes and infection sites of various viruses, the symptoms can be divided into respiratory viruses, gastroenteritis viruses, sexually transmitted infection viruses, hepatitis viruses, hepatitis viruses, hemorrhagic fever viruses, herpes viruses, etc.
Among these viruses, respiratory viruses are mainly transmitted through droplets or contact, so their regional infection range is faster than other viruses, and their transmission range is wider with the density and migration of populations.
(I) Influenza virus
Morphology and structure: Influenza virus particles are pleomorphic, generally spherical or filamentous, filamentous in new isolates and have strong infectivity. Its structure is from the inside to the outside:
① Core: consists of nucleic acids and nucleoproteins. The nucleic acid of influenza virus is segmented single fish RNA, which is prone to gene recombination between segments, causing mutation; nucleoproteins are type-specific antigens, with stable antigenicity and rarely mutations.
②Matrix protein (M protein): is located between the envelope and the core, and has the effect of protecting the core and maintaining the appearance of the virus. Its antigenicity is stable and has type specificity.
③ Envelope: A lipid bilayer located outside the M protein, containing the host cell membrane components, which are embedded with two structural proteins protruding from the surface of the virus, one is hemagglutinin (HA), and the other is neuraminidase (NA). Its antigenicity is the basis for dividing influenza virus subtypes.
clinical significance: Influenza virus replicates in respiratory columnar epithelial cells. The virus spreads into the respiratory tract of people susceptible to people. It relies on hemagglutinin to bind to the corresponding receptors of mucosal columnar epithelial cells to infect cells. It proliferates mainly in the respiratory tract and rarely enters blood, but metabolized toxin-like substances can enter the bloodstream and cause fever, headaches and general soreness.
(II), parainfluenza virus
biological characteristics: The morphological structure is similar to that of influenza virus, but it is large in size, and its nucleic acid is single-polluted RNA without segmentation. There are two glycoprotein spikes embedded in the envelope, one is HN with hemagglutination and neuraminidase activities. It has the adsorption effect of influenza virus HA, and the other is F, which has the effect of causing the virus to enter the host cell and spreading the virus between the host cells. Parainfluenza viruses are weak in resistance, not acid resistant, and are sensitive to heat.
Clinical significance: Parainfluenza virus is mainly transmitted through close contact with humans or aerosols by infected people, which can cause upper respiratory tract infection in children and adults.
(III), respiratory syncytial virus
biological characteristics: electron microscope negative staining is spherical, and a single virus particle has pleomorphism. Nucleic acid is a single-polluted RNA, without segmentation. The G protein on the envelope acts on the hemagglutinin protein HA similar to the influenza virus, and the F protein on the envelope is a fusion protein that mediates the penetration of the virus and cell fusion.
clinical significance: It is the most common virus that causes lower respiratory tract diseases in infants and young children. The most common transmission route is droplet infection, which is most likely to cause bronchioles and bronchiole pneumonia in infants and young children. If not treated in time, the mortality rate will be higher, and older children and adults will mainly cause upper respiratory tract infection.
(IV), adenovirus
adenovirus is a medium-sized unencapsulated virus with a single linear double strand DNA core. The basophilic inclusion body can be formed in the cell nucleus. Infection can be prevalent all year round and is found in all organs of the human body, which often causes respiratory diseases. Upper respiratory infections are common in common cold , pharyngitis, tonsillitis, and lower respiratory diseases include bronchitis, bronchioitis and pneumonia. After infection with adenovirus, the body can obtain long-lasting immunity to the same virus.
(V) Measles virus
Measles virus is spherical, with a single negative strand RNA core, three capsid proteins (L, P, N), outer cover, M protein inside the envelope, and hemagglutinin (H protein) and fusion protein (F) on the envelope surface.The H protein binds to the cell surface virus receptor CD6, and the infected host can produce cell fusion and multinucleated giant cells in the infected cells, with eosinophilic inclusion bodies in the cytoplasm and nucleus.
Measles is the most common acute respiratory infectious disease in childhood. The virus spreads directly through droplets. In winter and spring, viruses are prone to disease invade the upper respiratory tract and the epithelial cells of the ocular conjunctiva invade the upper respiratory tract and the ocular conjunctiva epithelial cells. They enter the blood through local lymphoid tissue , and the first viremia occurs. The virus invades the whole body lymphoid tissue and the mononuclear phagocytic cell system with the blood flow, and proliferates it again into the blood to form a second viremia, and infects the ocular conjunctiva, skin, oral mucosa, respiratory tract, digestive tract, blood vessels, etc. Measles virus can also cause relatively rare long-term complications, such as subacute sclerosis whole encephalitis (SSPE)
(VI), rubella virus
rubella virus is spherical, the core is a single positive strand RNA, and the outer envelope is encapsulated. There is hemagglutinin on the surface of the envelope. Rubella is an acute respiratory infectious disease characterized by systemic measles-like rashes with enlarged lymph nodes behind the ear and suboccipital lymph nodes. After local lymph node proliferates, the virus spreads throughout the body through viremia. Pregnant women are infected with viruses in the early stage of pregnancy and are transmitted vertically through the placenta to infect the fetus, which can cause congenital rubella syndrome. After birth, the fetus suffers from congenital heart disease, deafness, blindness, intellectual disability, etc.
(VII), coronavirus
coronavirus is a positive chain single-strand RNA virus, containing a membrane. It may be an important cause of upper respiratory tract infection in adults and older children. It mainly causes common colds, pharyngitis and pneumonia, and about 10%30% of common colds are caused by this virus.
SARS coronavirus is one of the coronaviruses. Its whole virus antigen does not cross-react with the common coronavirus antibodies present in the population and the monoclonal antibodies against the OC43 strain of the coronavirus. SARS coronavirus is a pathogen of severe acute respiratory syndrome. The transmission path of SARS is short-range respiratory droplet transmission!
(8), avian influenza virus
avian influenza virus is a subtype of influenza A virus, which can cause avian influenza colds. Currently, infectious subtypes such as H5N1 and H7N9 are found, and the mortality rate after virus infection is high.
