General Properties of Virus

 

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 schram 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, Allantois cavity Amniotic sac, and yolk sac inoculation.

 

Cell culture

Following cell cultures methods are given below namely primary cell culture, diploid cell culture and continuous 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 carcinoma of 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.