General Properties of Virus
Introduction
Viruses are tiny particles and can be only revealed
through electron microscopic study .the study of virus is known as virology ,
as it does not contain cellular organization , it will not belong to the
category of unicellular microorganism .usually viruses are very much smaller
than the bacteria. They contain only one type of nucleic acid either DNA
or RNA. They are strict intracellular
parasites as they surviving well within the host cells, viruses have a unique
features, when it is present in host tissue it seems to be in living form
whereas outside , it appears as nonliving form.
Usually viruses are pathogen; they are closely
associated with may lethal diseases .hepatitis, AIDS, Dengue, influenza are the
leading infections in worldwide. Stanley in the year 1935 pronounced that the viruses are crystallized
chemicals.
Geiger and schramm discovered that the infection nuclear material from
virus could infect host cell and yield complete virus progeny . moreover the
virus are not cultured in the artificial culture media but it can be cultivated
by following methods like animal inoculation Embryonated egg inoculation and
cell culture.
Animal inoculation
In this, laboratory animals are beings used to
isolate viruses especially, Arboviruses and coxackie viruses have been cultured
by this inoculation method. Once the virus is inoculated in to animals are
observed with viruses by cytopathic
effects.
Embryonated egg inoculation
Embryonated hens eggs are inoculated with viruses to have
been better isolation. It includes Chorioallantoic membrane, Allantoic cavity
Amniotic sac, and yolk sac inoculation.
Cell
culture
Following cell cultures
methods are given below namely primary cell culture, diploid cell culture and
continous cell line culture.
Primary cell
culture
Viral growth
is observed in normal cell when it is to be infected with viruses. usually
normal cells of animal and human being is used in this culture method.
Eg : Rhesus monkey
kidney cell culture, chick embryo fibroblast cell culture.
Diploid
cell strains
Human embryonic lung
cell strain and rhesus embryo cell strain are used.
Continuous
cell lines
HeLa ( Human carcinomaof cervix cell line ),
Hep-2 ( Human
epithelium of larynx cell line),
Vero ( Verve monkey
kidney cell line ),
McCoy ( Human synovial
carcinoma cell line)
Detection
of virus growth in cell cultures
Cytopathic effect, Haemadsorption ,Transformation and
immunofluorescence are the viral growth detection.
|
DNA VIRUSES DRAWING |
RNA VIRUSES DRAWING |
0 Comments