bohomolets microbiology lecture #5
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Virology
Reproduction and cultivation
Types of virus interaction with cell
Abortive. When abortive infection replication of virus progeny is interrupted in someone stage.
Productive. Productive infection results in viral replication with the production of virus progeny and death of the host cel.
Integrative (latent, persistent). Integrative infection occur when virus genome integrate into cell chromosome..
Stages of viral replication
1. Adsorption (attachment)
2. Penetration
3. Uncoating of the viral genome
4. Gene expression, transcription, early and late viral protein synthesis
5. Genome replication
6. Assembly of progeny virions
7. Release virions from cell
Early events
Middle events
Late events
Adsorption of animal viruses
Entry of enveloped viruses into host cell
a) b)
General scheme replication of poxviruses
Replication in DNA viruses
Replication in RNA viruses
Maturation of virions
Assembly of viruses is a self-assembly process
Tobacco mosaic virus maturation
Nucleus of a cell, containing a crystalline mass of adenoviruses
Release of mature viruses from host cell
Budding release of retroviruses
Maturation of an enveloped virus
Основні ефекти, що викликають віруси в клітинах: Морфологічні (ЦПД, вірусні включення) Фізіологічні (зміна клітинних мембран – плинність, ліпідний
склад, мембранний потенціал) Біохімічні (переключення генетичної інформації, зміни у
обмінних процесах, зміни у цитоскелеті клітин, поява нових ферментів)
Генотоксичні (руйнуваня або зміни геному клітини, хромосомні аберації)
Біологічні (поява нових антигенів, малігнізація)
Methods cultivating of animal viruses
Live animal organism Chicken embryo Cell (or tissue) culture
Cultivation viruses in newborn mice
Advantages:
Study of pathogenesis
Examination of vaccines and antiviral drags
Disadvantages:
Not-universal method
Presence own viruses and bacteria in animal organism
Sign of viral infection in animals
Mouse with paralysis of back extremities
Death
Symptoms of illness
Newborn mice that are behind in development
Virus cultivation in bird embryos
Advantages:
Standardized system
Sterile system
Possibility to cultivate viruses and make viral vaccines
Disadvantages:
Not-universal method
Possible presence own latent viruses
Virus cultivation in bird embryos
The signs of viral growth in bird embryos are:
death of the embryo
defects in embryonic development
pocks ( localized areas of damage in the membranes )
Other methods for detection of viruses that do not produce visible changes in embryo:
direct examination with electron microscope
hemagglutination test
serological test
Pocks developing on a chorioallantoic membrane caused by herpes simplex viruses I and II types
Cell culture
there is the aggregate of human, animal or plant cells that are cultivated in vitro with using of complex nutrient mediums and conditions of cultivation
Cell cultures
Cells of macaque kidneys
Cells of human embryo
HeLaCells of pig embryo (RES)
Methods detection of viruses in cell culture
Cytopathic effect (CPE) Inclusion body formation Coloured test Plaque formation under agar or bentonit Hemadsorbtion Hemagglutination Detection viral antigens in infected cell with
serological test Detection of virions under electron microscope
Types of viral CPE
Type of CPE Instance
Cell rounding and detachment from the substrate
Smallpox virus, influenza virus
Cell lysis Polioviruses, togavirus
Syncytium formation (a mass of fused cells)
Respiratory syncytial virus, herpes simplex viruses
Transformation and proliferation. Oncogenic viruses as retroviruses, some herpesviruses
Cell lysis caused by enterovirus
Normal cells Vero Infected cells Vero after poliovirus reproduction
Syncytium formation caused by herpesvirus
CPE caused by adenovirus
Intact cells HeLa Clumping of infected cells
Inclusion body formation
Gvarniery bodies
Negry bodies
Plaque formation
Plaques under agar
Plaques under bentonit
Normal cells Infected cells
Plagues
Detection viruses that have hemagglutinins
Hemagglutination Hemadsorbtion
Red cells Viruses Hemagglutination
Attachment phages on bacterial surface
Phages that attached to bacterial flagellum
Penetration of tailed phage
Multiplication of bacteriophages
Releasing phages from ruptured bacterium
A bacterial cell, crowded with viruses, has ruptured and released numerous virions that can attack nearby susceptible cells.
The lysogenic state in bacteria
Lysogeny
is a condition in which viral DNA is inserted into the bacterial chromosome and remains inactive for an extended period.
Virulent phage propagates in bacteria and induces its death
Temperate phage after entering in the bacterium integrates their DNA in the chromosome of the host cell and turn into prophage.
Life cycle of phage lambda – lytic and reproductive infection
Lysogenic cell is the bacterial cell carrying a prophage
Animal DNA viruses families
Family Strand type
Capsid type Envelope Size
Common Name of Important Members
Poxviridae Double None + 130-300 Smallpox virus; complex virus; brick-shaped
Herpes-viridae
Double Icosahedral + 150-200 Herpes simplex virus, Varicella zoster virus, Epstein-Barr virus
Adeno-viridae
Double Icosahedral - 70-90 Human adenoviruses
Papova-viridae
Double Icosahedral - 45-55 Human papillomavirus
Hepadna-viridae
double Icosahedral + 42 Hepatitis B virus
Parvo-viridae
Single Icosahedral - 18-26 Parvovirus B19
Animal RNA viruses families (1)
Family Strand type
Capsid Type Envelope Size (nm)
Common Name of Important Members
Picorna-viridae
Single Icosahedral - 20-30 Hepatitis A virus, poliovirus, coxsackieviruses, rhinoviruses
Calciviridae Single Icosahedral - 35-40 Norwalk virus
Togaviridae Single Icosahedral + 45-70 Rubella virus, western equine encephalitis
Flaviviridae Single Icosahedral + 40-70 Yellow fever virus, Japanese encephalitis virus
Paramyxo-viridae
Single Helical + 125-250 Parainfluenza virus, mumps virus, measles virus
Animal RNA viruses families (2)
Family Strand type
Capsid Type Envelope Size (nm)
Common Name of Important Members
Filoviridae Single Helical + 790-970 Ebola and Marburg viruses
Bunyaviridae Single Helical + 90-100 Bunyamwera virus, Hanta virus
Reoviridae Double Icosahedral - 60-80 Human rotavirus, Colorado tick fever virus
Orthomyxo-viridae
Single Helical + 80-120 Influenza viruses
Animal RNA viruses families (3)
Family Strand type
Capsid Type
Envelope Size (nm)
Common Name of Important Members
Rhabdo-viridae
Single Helical + 60-75 Rabies virus
Retroviridae Single Icosahedral + 100 Human immunodeficiency virus (AIDS), oncoviruses
Arenaviridae Single ? + 50-300 Lassa virus; lymphocytic choriomeningitis virus
Corona-viridae
Single Helical + 80-130 Human infectious bronchitis and corona viruses
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