Detail the cause of influenza

Cause introduction of influenza

Single strand RNA of influenza virus to virus, the virus is being mucus Division. Generally irregular spherical, enveloped, diameter 80 ~ 120nm, when the new separation was filament shape, or form. Viral RNA and nucleoprotein core particle and a small amount of other proteins. The structure of RNA virus for replication, the virus nucleoprotein as soluble antigen (S antigen), of stability, with type-specific, whereby the virus is divided into A, B, C III, can be used for diagnostic indicators, but no protection.

Virus membrane proteins from the endometrium (MP) and the class of lipid membrane composition, type-specific endometrial protein also has the stability of antigens, but no protection. Virus envelope glycoprotein surface there are two processes with different characteristic surface antigen (strain features), according to the same type of virus or virus strains into subtypes. Rod-like processes for the hemagglutinin (hemagglutinin, referred to as H), with the virus on sensitive cell adhesion receptors, and may cause a variety of animal red blood cell aggregation; the dumbbell-shaped protrusions to the neuraminidase (neuraminidase, referred to as N ), hydrolysis of cell surface glycoprotein with N-acetylneuraminate role, so that replication of the virus can be released from the cell surface. A and B influenza virus H and N antigens, while the C-type is the lack of N antigen. The two kinds of surface antigens (H, N) prone to mutation, the time when there is a small quantity (called antigenic drift, antigenic drift) generate new influenza virus strains, called variant, often leading to a prevalence of 2 ~ 3 years occur once.

When the H, N occurs when the full qualitative (called antigenic mutations, antigenic shift) generate a new subtype, often lead to a worldwide pandemic, generally occur 10 to 40 years time. Influenza viruses such as influenza in the last 45 years has gone through four major variations, that the original alpha (A 0, A0, H0N1, 1946 years ago, popular), sub-alpha (A 1, A1, H1N1, 1946 years after the epidemic), the Asian influenza (A 2, A2, H2N2, 1957 years after the epidemic), and the Hong Kong-type (A 3, A3, H3N2, 1968 years after the epidemic).

Since then its surface antigen continues to mutate, 80 years later is still a 3 and A-1 mainly localized epidemic, not a major antigen mutation. Still think that this constant from quantitative to qualitative change in the antigenic variation is due to mutation of the virus itself (through recombinant infected people or animals caused by influenza virus) and the population immunity selection. From the serological survey confirmed a cycle of repetition of such variation trend, as in January 1976 in the United States swine virus (HswN1) epidemic, and in May 1977 took place in Northeast China A-1 (H1N1), respectively 1918 to 1928 the history of epidemic strains and strains 1946 and 1957, similar.

Antigenic variation of influenza B virus as influenza A significant, but there are also popular because of antigenic variation caused by about 4 to 7 years for each occurrence; hepatitis C virus is quite stable.

As the influenza virus variant and more complex virus name, the provisions of the 1971 World Health Organization named the following order:

Type the host name (such as man can not write), area, number, year of virus isolation, antigen components indicated in parentheses, such as A / Hong Kong / 1 / 68 (H2N2).

Summary

Influenza virus does not heat and acid (56 ℃ or when the non-pathogenic pH3), alcohol, phenol, bleaching powder, and also sensitive to ultraviolet light. 1% hydrochloric acid, lactic acid, acetic acid could serve as a disinfectant. Under natural conditions, only B and hepatitis C virus infection, while influenza viruses are can still infect pigs, horses, birds and so on. Experimental animals can be infected ferrets only incurred respiratory inflammation. Common chicken, human embryonic kidney, bovine kidney, dog kidney culture virus.