A) General description about virus
Viruses are simple, noncellular entities consisting of one or more molecules either DNA or RNA enclosed in a coat of protein. They can reproduce only within living cells. Viruses are smaller than prokaryotic cells ranging from 0.02 to 0.3 micrometer. A fully assembled infectious virus is known as a virion. The main function of virion is to deliver its DNA or RNA genome into the host cell so that genome can be expressed by the host cell. Three major points which completely differentiates between virus and living cells are:-
(1) Their simple, non-cellular organization;
(2) The presence of either DNA or RNA, but not both, in almost all virions (human cytomegalovirus has a DNA genome and four…show more content… Some general properties of this virus are as follows:-
Table 1.2) Influenza virus properties
Size of virus 80-120 nm in diameter
Shape of virus Spherical or pleomorphic
Envelope They have a lipid membrane envelope that contains the two glycoproteins: hemagglutinin (HA) and neuraminidase (NA).
Genetic material Consists of eight, single negative-strand RNAs that can range between 890 and 2340 nucleotides long
Classification Types Description
Influenza A virus
It can cause flu epidemics. Influenza A virus is found in human and many other animals. Wild birds are thought to be natural reservoirs of this virus and the source of it in other animals.
Influenza type A viruses are divided into subtypes based on two proteins on the surface of the virus. These proteins are called hemagglutinin (HA) and neuraminidase (NA). There are 15 different HA subtypes and 9 different NA subtypes. Many different combinations of HA and NA proteins are…show more content… Some spikes have enzyme neuraminidase and other hemagglutinin protein. These help the virus in penetrating mucous layers of the respiratory epithelium to reach host cells and binds the virions to red blood cell membranes and cause hemagglutination. A nonglycosylated protein, the M or matrix protein, is found on the inner surface of the envelope and helps stabilize it.
B) Antiviral compounds of plants
Viral diseases like herpesviruses, retroviruses, orthomyxoviruses, hepatitis B virus and hepatitis C virus (HCV) can be treated by commercially available drugs. Viral infections have increased in such a manner that no particular treatment is available. Also due to the emergence of new resistant viral strains, the development of novel antiviral agents is essential. Natural products have proved to be an important source of lead molecules and many extracts and compounds of plant origin with antiviral activity have been