Viruses can be cultivated through several methods, including inoculation in animals, embryonated eggs, and tissue/cell culture. Inoculation in animals allows study of viral replication and immune responses but is expensive. Embryonated eggs are widely used as they are inexpensive and viruses can replicate, though not all human viruses grow well. Tissue/cell culture is now preferred, using primary cultures, continuous cell lines, or explant cultures. Growth is detected through cytopathic effects, staining, or metabolic changes in infected cells.
Poxviruses are brick or oval-shaped viruses with large double-stranded DNA genomes. Poxviruses exist throughout the world and cause disease in humans and many other types of animals. Poxvirus infections typically result in the formation of lesions, skin nodules, or disseminated rash.
Viral classification and Types of Replication in virus Rakshith K, DVM
Precise presentation on Viral classification and Types of replication in Virus.
Entry of virus
Spread of virus
General steps in a virus replication cycle
Attachment, Penetration, Uncoating, Multiplication
Multiplication of Single-Stranded RNA (ss RNA) Viruses
Multiplication of Double-Stranded RNA (ds RNA) Viruses
Multiplication of Single-Stranded DNA (ss DNA) Viruses
Multiplication of Double-Stranded DNA (ds DNA) Viruses
Release of new virions
Common viral diseases of Bovines
A picornavirus is a virus belonging to the family Picornaviridae, a family of viruses in the order Picornavirales. Vertebrates, including humans, serve as natural hosts. Picornaviruses are nonenveloped viruses that represent a large family of small, cytoplasmic, plus-strand RNA viruses with a 30-nm icosahedral capsid.
Poxviruses are brick or oval-shaped viruses with large double-stranded DNA genomes. Poxviruses exist throughout the world and cause disease in humans and many other types of animals. Poxvirus infections typically result in the formation of lesions, skin nodules, or disseminated rash.
Viral classification and Types of Replication in virus Rakshith K, DVM
Precise presentation on Viral classification and Types of replication in Virus.
Entry of virus
Spread of virus
General steps in a virus replication cycle
Attachment, Penetration, Uncoating, Multiplication
Multiplication of Single-Stranded RNA (ss RNA) Viruses
Multiplication of Double-Stranded RNA (ds RNA) Viruses
Multiplication of Single-Stranded DNA (ss DNA) Viruses
Multiplication of Double-Stranded DNA (ds DNA) Viruses
Release of new virions
Common viral diseases of Bovines
A picornavirus is a virus belonging to the family Picornaviridae, a family of viruses in the order Picornavirales. Vertebrates, including humans, serve as natural hosts. Picornaviruses are nonenveloped viruses that represent a large family of small, cytoplasmic, plus-strand RNA viruses with a 30-nm icosahedral capsid.
Animal viruses are self replicating, intracellular parasites that completely rely on host animal cell for reproduction. They use the host's cellular components to replicate, then leaves the host cell to infect other cells.
Viruses are infectious intracellular obligate parasites with subcellular level of organisation and without protoplasm, cell, cell organells and the molecular machineries for energy metabolism and protein synthesis,Grouped on the basis of size and shape, chemical composition and structure of the genome and mode of replication
most viruses have a specific shape that is determined by the capsomeres or the envelope.
Capsid symmetry - Three types
(1) HELICAL CAPSID
(2) ICOSAHEDRALCAPSID
(3) COMPLEX CAPSID
Capsid - large macromolecular structures.
Made up of proteins called capsomers.
Chemical unit of capsomers are polypeptide chain.
Capsid - surrounded by lipoprotein layer called envelop
Envelop is made up of proteins and glycoproteins
Presence of lipid -envelope seems flexible and loose.
Envelope is composed of both the host viral components.
projections on the envelope known as spikes/peplomers which are arranged into distinct units.
The Paramyxoviridae is a family of single-stranded RNA viruses known to cause different types of infections in vertebrates. Examples of these infections in humans include the measles virus, mumps virus, parainfluenza virus, and respiratory syncytial virus (RSV).
Animal viruses are self replicating, intracellular parasites that completely rely on host animal cell for reproduction. They use the host's cellular components to replicate, then leaves the host cell to infect other cells.
Viruses are infectious intracellular obligate parasites with subcellular level of organisation and without protoplasm, cell, cell organells and the molecular machineries for energy metabolism and protein synthesis,Grouped on the basis of size and shape, chemical composition and structure of the genome and mode of replication
most viruses have a specific shape that is determined by the capsomeres or the envelope.
Capsid symmetry - Three types
(1) HELICAL CAPSID
(2) ICOSAHEDRALCAPSID
(3) COMPLEX CAPSID
Capsid - large macromolecular structures.
Made up of proteins called capsomers.
Chemical unit of capsomers are polypeptide chain.
Capsid - surrounded by lipoprotein layer called envelop
Envelop is made up of proteins and glycoproteins
Presence of lipid -envelope seems flexible and loose.
Envelope is composed of both the host viral components.
projections on the envelope known as spikes/peplomers which are arranged into distinct units.
The Paramyxoviridae is a family of single-stranded RNA viruses known to cause different types of infections in vertebrates. Examples of these infections in humans include the measles virus, mumps virus, parainfluenza virus, and respiratory syncytial virus (RSV).
Viruses are obligate intracellular parasites so they depend on host for their survival. They cannot be grown in non-living culture media or on agar plates alone, they must require living cells to support their replication.Cultivation of viruses can be discussed under following headings:
Animal Inoculation
Inoculation into embryonated egg
Cell Culture
The earliest indications of the biological nature of viruses came from studies in 1892 by the Russian scientist Dmitry I. Ivanovsky and in 1898 by the Dutch scientist Martinus W. Beijerinck.
Beijerinck first surmised that the virus under study was a new kind of infectious agent, which he designated contagium vivum
fluidum, meaning that it was a live, reproducing organism that differed from other organisms.
Both of these investigators found that a disease of tobacco plants could be transmitted by an agent, later called tobacco mosaic virus, passing through a minute filter that would not allow the passage of bacteria.
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The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
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2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
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Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
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Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
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Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
2. Introduction to viruses
Definition:
• An infective agent that typically consists of a nucleic acid molecule in
a protein coat, is too small to be seen by light microscopy, and is able
to multiply only within the living cells of a host.
• The are 10-100 times smaller(20-300nm) than most bacteria
• They can grow only in animals or plants or microorganisms (Obligate
intracellular parasites)
• Viruses do not have cells that divide; new viruses are assembled in the
infected host cell
• But unlike still simpler infectious agents, viruses contain genes, which
gives them the ability to mutate and evolve, contain a nucleic acid
either DNA or RNA which is enclosed by a protein coat called nucleo-capsid.
• Evolved from plasmids : pieces of DNA that can move between cells while others
may have evolved from bacteria.
• The structurally complete, matured and infectious virus is called Virion.
• In 1897, Martinus Beijerinck suggested that tiny particles in the juice caused the
disease, and he named these particles viruses, after the Latin word for “poison.”
• Over 5,000 species of viruses have been discovered.
3. • A virus consists of two or three parts: genes,
made from either DNA or RNA, long molecules
that carry genetic information
• Protein coat that protects the genes; and in
some viruses, an envelope of fat
• Viruses vary in shape from the simple helical
and icosahedral to more complex structures.
4. Classification of virus
International Committee on Taxonomy of Viruses(ICTV)
Basis on the host they lives.
1. Animal viruses:
• Have DNA and may have RNA also
• Viruses of animal host
• Rabies, Polio, Mumps, Chicken pox, Small pox, and
Influenza.
2. Plant Viruses:
• have RNA and infected potato, sugarcane, tabacco,
cucurbitis and other higher plants. Viruses which show
their live characteristics when attached to plants.
• Tobacco mosaic virus (TMV), Banana streak virus,
Carrot thin leaf virus
3.Bacterial Virus: Have DNA and are called
Bacteriophages(phages) ( T1, T2, T3, and T4.)
5. Classification of viruses
• Based on physicochemical properties/characteristics:
1. Primary characteristics
• Chemical nature of nucleic acid- RNA or DNA, single
stranded/ double stranded, single/ segmented genome,
• Structure of virion-Helical icosahedral or complex,
nacked or enveloped, etc.
• Site of replication-Nucleus or cytoplams
2. Secondary characteristics
• Host range- host specific, specific host tissues or cell type
• Specific surface structure- eg: Antigenic properties
• Mode of transmission- eg: feces
6.
7.
8. • Nomenclature of viruses is decided by Internation
committee on taxanomy of viruses
• Viruses are grouped into families named by suffix
viridae, subfamilies virinae and genera virus
Sizes of viruses
9. Morphology of viruses
• Virion: Complete, mature, fully developed viral particle
composed of nucleic acid surrounded by a coat that
protects it from the environment and serves as a vehicle of
transmission from one host cell to another host cell.
• Nucleic acid-either DNA or RNA
• Capsid or envelope- protein coat surrounding the NA is
called capsid composed of protein subunits called as
capsomeres. The capsomere might be of single type or
different types proteins depending on virus. Structure
might be covering capsid called as envelope which is
composed of proteins, lipids, carbohydrates.
• Viruses are not cellular and therefore do not have a
nucleus, cytoplasm membrane.
13. T-even phages
• T-even phages, also known as the E. coli phages, are a
group of double-stranded DNA bacteriophages from the
family Myoviridae.
• T-even phages(T1,T2,T3,T4,T5,T6,T7)
• Tadpole shaped, with hexagonal head and cylindrical tail.
• Head consists of nucleic acids(ds DNA) surrounded by a
protein coat or capsid.
• The base of the tail portion have six pins and six tails
attached together that bind to specific receptor sites on
the bacterial surface.
• Phages T1, T5 and lambda of E. coli do not possess a
contractile sheath and tails of phages T3 and T7 of E.coli
and P22 Salmonella are short and non-contractile.
14.
15. Life cycle/replication of Bacteriophages
• Bacteriophage, also called phage or bacterial virus, any of
a group of viruses that infect bacteria.
• Discovered by Frederick W. Twort in Great Britain (1915)
and Felix d’Herelle in France (1917).
• Bacteriophage, meaning “bacteria eater”
There are two different types of life cycle:
1. Lytic or Virulent cycle: In this cycle, there is intracellular
multiplication of phages followed by lysis and release of
progeny virions.
2. Temperate or avirulent or lysogenic cycle: In lysogenic
cycle, the phage DNA becomes integrated with the bacterial
genome, replicating synchronously without any cell lysis.
18. Cultivation of Viruses
• Viruses are obligate intracellular parasites, which
cannot be grown on inanimate culture media.
• Viruses are host specific and grow only in selective
hosts. Virologists use only a suitable host system for
cultivation of a virus.
• Viruses cannot grow in artificial media. They
cannot grown in non-living culture or on agar
plates alone, they must require living cells to
support their replication.
• There is no universal cell that will support all
viruses.
19. Main purpose of virus cultivation
• To isolate and identify viruses
in clinical samples.
• To prepare viruses for vaccine
production.
• To do research on viral
structure, replication ,
genetics and effects on host
cells.
21. 1). Inoculation of Virus in
Animals
• Viruses which are not cultivated in embryonated
egg and tissue culture are cultivated in laboratory
animals. e.g: mice, guinea pig , hamester , rabbits
and primates are used.
• The selected animals should be healthy and free
from any communicable diseases.
• Suckling mice (less than 48- 300 hours old) are
most commonly used.
• Different ways of inoculation in mice are:
1). Intracerebral.
2). Subcutaneous.
3). Intraperitoneal.
4). Intranasal.
22. Observation
•The growth of the virus
in inoculation animals
may be indicated by
death, diseases or
visible lesions.
23. Advantages and disadvantages
of animal inoculation :
Advantages:
• Production of antibodies can be identified.
• Diagnosis , pathogenesis and clinical symptoms
are determined.
• Primary isolation of certain viruses.
• Mice provide a reliable model for studying viral
replication.
• Used for the study of immune responses,
epidemology and oncogenesis.
24. Disadvantages:
• Expensive and difficulties in maintainance of
animals.
• Difficulty in choosing of animals for particular
virus.
• Some human viruses cannot be grown in animals
or can be grown but do not cause diseases.
• Mice do not provide models for vaccine
development.
25. 2). Inoculation of virus into
embryonated egg
• The process of cultivation of viruses in
embryonated eggs.
• Depend upon the type of egg being used.
• First cultivated by Goodpasture(1931), further
developed by Burnet.
• Egg provide a suitable means for :
i. The primary isolation and identification of
viruses.
ii. The production of vaccines.
iii. The maintenance of stock culture.
26.
27. The egg is broken and virus is isolated from tissue of egg
Incubation can be done at 36°C for respective incubation time of the
virus
Eggs are selected (7-12 days old), Sterilization of egg’s cell is done by
using iodine(disinfectant) and penetrated with a small sterile drill
28. Observation
• Virus growth and multiplication in
the egg embryo is indicated by the
death of the embryo , by embryo
cell damage , or by the formation
of typical pocks or lesions on the
egg membrane.
29. Advantages and disadvantages of inoculation into
embryonated egg
• Widely used method for the isolation of virus and
growth.
• Cost effective and maintenance is much easier.
• The embryonated eggs are readily available.
• They are free from contaminating bacteria and many
latent viruses.
• Ideal substrate for the viral growth and replication.
• less labour is needed.
• Widely used method to grow virus for some vaccine
production.
• Defence mechanisms are not involved in
embryonated eggs.
30. Disadvantages
• The site of inoculation for varies with different
virus . That is , each virus have different sites
for growth and replication.
31. 3) Tissue culture
• Cultivation of bits of tissues and organs in vitro had been used by physiologists
and surgeons for the study of morphogenesis and wound healing.
• The first application of tissue culture in virology was done by Steinhardt and
colleagues (1913), who maintained the vaccinia virus in fragments in rabbit
cornea.
• Maitland (1928) used chopped tissue in nutrient media for cultivation of
vaccinia viruses.
• Before the advent of cell culture, animal viruses could be propagated only on
whole animals or embryonated chicken eggs.
• Cell cultures have replaced embryonated eggs as preferred type of growth
medium for many viruses.
• Cell culture consists of cells grown in culture media in the laboratory.
• There are three types of tissue culture:
• 1). Organ culture.
• 2). Explants culture.
• 3). Cell culture.
46. 3. Continuous cell lines
• Animal cells capable of indefinite growth are
called continuous cell lines or cell lines.
• These are the cells of a single type, usually
derived from cancer cells, that are capable of
continuous serial cultivation indefinitely.
• Standard cell lines derived from human cancers,
such as HeLa , HEp–2 and KB cell lines have been
used in laboratories throughout the world for
many years.
47. • These cell lines may be maintained by serial
sub-cultivation or stored in the cold (-70⁰C )
for use when necessary.
• Some cell lines are now permitted to be used
for vaccine manufacture, for example: Vero
cells for rabies vaccine.
48.
49. Advantages of cell culture
• Relative ease, broad spectrum, cheaper and
sensitivity
Disadvantage of cell culture
• The process requires trained technicians with
experience in working on a full time basis.
• State health laboratories and hospital
laboratories do not isolate and identify viruses
in clinical work.
• Tissue or serum for analysis is sent to central
laboratories to identify virus.
50. Detection of virus growth
• The following methods are available to detect
the virus growth in the cell or tissue cultures.
a). Cytopathic effect.
b). Haemadsorption.
c). Interference.
d). Transformation.
e). Immuno-fluorescence.
f). Metabolic inhibition.
51. a). Cytopathic effect.
• Many viruses cause morphological changes in cultured cells in
which they grow. These changes can be readily observed by
microscopic examination of the cultures.
• These changes are known as ‘cytopathic effects’ (CPE) and the
viruses causing CPE are called ‘cytopathogenic viruses’.
• The CPE produced by different groups of viruses are characteristic
and help in presumptive identification of virus isolates.
• For example, enteroviruses produce rapid CPE with crenation of
cells and degeneration entire cell sheet ; measles virus produce
syncytium formation; herpes virus causes discrete focal
degeneration; adenovirus produce large granular clumps of
grapes.