Viruses that infect and parsitized bacteria is known as bacteriophage.
It was discovered by Frederick.W.Twort in Great Britian (1915) and Felix d’ Herelle in France(1917).
D’ Herelle coined the term bacteriophage meaning ‘bacterial eater’ to describe the agent’s bacteriocidal activity. He observed lysis of a broth culture of a dysentry bacillus.
A bacteriophage (informally, phage) is a virus that infects and replicates within a bacterium. The term is derived from "bacteria" and the Greek (phagein), "to devour". Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have relatively simple or elaborate structures. Their genomes may encode as few as four genes, and as many as hundreds of genes. Phages replicate within the bacterium following the injection of their genome into its cytoplasm. Bacteriophages are among the most common and diverse entities in the biosphere.
Phages are widely distributed in locations populated by bacterial hosts, such as soil or the intestines of animals. One of the densest natural sources for phages and other viruses is sea water, where up to 9×108 virions per milliliter have been found in microbial mats at the surface,] and up to 70% of marine bacteria may be infected by phages. They have been used for over 90 years as an alternative to antibiotics in the former Soviet Union and Central Europe, as well as in France. They are seen as a possible therapy against multi-drug-resistant strains of many bacteria (see phage therapy). Nevertheless, phages of Inoviridae have been shown to complicate biofilms involved in pneumonia and cystic fibrosis, shelter the bacteria from drugs meant to eradicate disease and promote persistent infection
Viruses are small, acellular particles that can replicate only in a host cell. They are obligatory intracellular parasites.They
consist of a nucleic acid genome enclosed in a protective protein shell or capsidBacteriophage is the virus that infect bacteria.Bacteriophages were discovered by Frederick Twort(1915)and Felix d'Herelle(1917).
Viruses that infect bacteria.
Occur widely in nature in close association with bacteria.
Readily isolated from faeces, sewage and other natural sources.
Tadpole shaped, with hexagonal head and a cylindrical tail.
Head consists of a tightly packed core of ds DNA surrounded by a protein coat or capsid.
The tail composed of a contractile sheath surrounding the hollow core
Terminal base plate having prongs or tail fibres attached.
A bacteriophage (informally, phage) is a virus that infects and replicates within a bacterium. The term is derived from "bacteria" and the Greek (phagein), "to devour". Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have relatively simple or elaborate structures. Their genomes may encode as few as four genes, and as many as hundreds of genes. Phages replicate within the bacterium following the injection of their genome into its cytoplasm. Bacteriophages are among the most common and diverse entities in the biosphere.
Phages are widely distributed in locations populated by bacterial hosts, such as soil or the intestines of animals. One of the densest natural sources for phages and other viruses is sea water, where up to 9×108 virions per milliliter have been found in microbial mats at the surface,] and up to 70% of marine bacteria may be infected by phages. They have been used for over 90 years as an alternative to antibiotics in the former Soviet Union and Central Europe, as well as in France. They are seen as a possible therapy against multi-drug-resistant strains of many bacteria (see phage therapy). Nevertheless, phages of Inoviridae have been shown to complicate biofilms involved in pneumonia and cystic fibrosis, shelter the bacteria from drugs meant to eradicate disease and promote persistent infection
Viruses are small, acellular particles that can replicate only in a host cell. They are obligatory intracellular parasites.They
consist of a nucleic acid genome enclosed in a protective protein shell or capsidBacteriophage is the virus that infect bacteria.Bacteriophages were discovered by Frederick Twort(1915)and Felix d'Herelle(1917).
Viruses that infect bacteria.
Occur widely in nature in close association with bacteria.
Readily isolated from faeces, sewage and other natural sources.
Tadpole shaped, with hexagonal head and a cylindrical tail.
Head consists of a tightly packed core of ds DNA surrounded by a protein coat or capsid.
The tail composed of a contractile sheath surrounding the hollow core
Terminal base plate having prongs or tail fibres attached.
Obligate intracellular, unable to self-replicate.
Once inside living cells, viruses induce the host cell to synthesize virus particles.
The genome is either DNA or RNA (single or double stranded).
Viruses do not have a system to produce ATP.
Viruses range in size from 25 to 270 nm.
Viral tropism!!
The classification of viruses is based on nucleic acid type, size and shape of virion, and presence or absence of an envelope.
Viral Structure
I . Virion is the entire viral particle.
2. Capsid is the protein coat that encloses the genetic material.
3. Capsomer is the protein subunit that makes up the capsid.
4. Nucleocapsid is composed of the capsid and genetic material.
5. The envelope is the outer coating composed of a phospholipid bilayer, which is composed of viral-encoded glycoproteins and sometimes viral encoded matrix proteins. The envelope is derived from a host cell's membrane.
Some viruses use the plasma membrane, whereas others use endoplasmic reticulum, Golgi, or nuclear membranes. Naked nucleocapsids are viruses with no envelopes.
Bacteria are microscopic, single-celled organisms that thrive in diverse environments. These organisms can live in soil, the ocean and inside the human gut. Humans' relationship with bacteria is complex. Sometimes bacteria lend us a helping hand, such as by curdling milk into yogurt or helping with our digestion.
TOBACCO MOSAIC VIRUS (Genome organization &their replication) TMV is a plant virus which infects a wide range of plants, especially tobacco and other members of the family Solanaceae and cucumbers, and a number of ornamental flowers.
1.INTRODUCTION
2.HISTORY
3.MORPHOLOGY
4.STRUCTURE
5.CLASSIFICATION
6.CHARACTERSTICS
7.DISEASES
8.CONCLUSION
REFRENCES
Mycoplasmas are prokaryotic , without cell wall & have been placed under the class Mollicutes & the order Mycoplasmatales.
Mycoplasma are the smallest microorganism which have been known to cause a number of disease in animals &human kind.
The cells are bounded by a soft trilamellar lipoproteinaceous unit membrane containing sterols. Because of their plasticity , they can pass through bacterial filters & have often been mistaken for viruses.
Obligate intracellular, unable to self-replicate.
Once inside living cells, viruses induce the host cell to synthesize virus particles.
The genome is either DNA or RNA (single or double stranded).
Viruses do not have a system to produce ATP.
Viruses range in size from 25 to 270 nm.
Viral tropism!!
The classification of viruses is based on nucleic acid type, size and shape of virion, and presence or absence of an envelope.
Viral Structure
I . Virion is the entire viral particle.
2. Capsid is the protein coat that encloses the genetic material.
3. Capsomer is the protein subunit that makes up the capsid.
4. Nucleocapsid is composed of the capsid and genetic material.
5. The envelope is the outer coating composed of a phospholipid bilayer, which is composed of viral-encoded glycoproteins and sometimes viral encoded matrix proteins. The envelope is derived from a host cell's membrane.
Some viruses use the plasma membrane, whereas others use endoplasmic reticulum, Golgi, or nuclear membranes. Naked nucleocapsids are viruses with no envelopes.
Bacteria are microscopic, single-celled organisms that thrive in diverse environments. These organisms can live in soil, the ocean and inside the human gut. Humans' relationship with bacteria is complex. Sometimes bacteria lend us a helping hand, such as by curdling milk into yogurt or helping with our digestion.
TOBACCO MOSAIC VIRUS (Genome organization &their replication) TMV is a plant virus which infects a wide range of plants, especially tobacco and other members of the family Solanaceae and cucumbers, and a number of ornamental flowers.
1.INTRODUCTION
2.HISTORY
3.MORPHOLOGY
4.STRUCTURE
5.CLASSIFICATION
6.CHARACTERSTICS
7.DISEASES
8.CONCLUSION
REFRENCES
Mycoplasmas are prokaryotic , without cell wall & have been placed under the class Mollicutes & the order Mycoplasmatales.
Mycoplasma are the smallest microorganism which have been known to cause a number of disease in animals &human kind.
The cells are bounded by a soft trilamellar lipoproteinaceous unit membrane containing sterols. Because of their plasticity , they can pass through bacterial filters & have often been mistaken for viruses.
Bacteriophages are the most abundant entities on earth. These bacterial viruses have genetic material in the form of either DNA or RNA, encapsidated by a protein coat.The capsid is attached to a tail which has fibers, used for attachments to receptors on bacterial cell surface.
introduction of bacteriophage , discovery, morphology, structure and life cycle of bacteriophage,
imp. of bacteriophage and other briefly define lytic and lysogenic cycle.
Bacteriophage is the most common and extensively studied virus. The life cycle of bacteriophages. The transfer of their genetic system via the process of transduction (Generalised and Specialised) and studying the gene mapping in phages. This theoretical explanation about viruses and their genetic system will help the learner in the fields of biotechnology, microbiology, basic science, life science, and various other fields of biology.
BACTERIAL TRANSDUCTION
PRESENTED BY SAIRA FATIMA
ROLL NO:31
MSc 4 [2018-2020]
Department of MicroBiology & Molecular Genetics
University of the Punjab
Lahore, Pakistan
A bacteriophage is a type of virus that infects bacteria. In fact, the word "bacteriophage" literally means "bacteria eater," because bacteriophages destroy their host cells. All bacteriophages are composed of a nucleic acid molecule that is surrounded by a protein structure
A comprehensive illustration about viruses and their genetic system. The life cycle of bacteriophages. The transfer of their genetic system via the process of transduction (Generalised and Specialised) and studying the gene mapping in phages.
Nematodes” are Round worms
Most nematodes are free living in fresh water, sea water and soil.
Are elongated bilaterally symmetrical, Non-segmented cylindrical worms, tapering at both the ends.
Sexes are separate (diecious), male is smaller than female & its posterior end is curved ventrally.
Females are either Viviparous (produces larvae/ embryo), Oviparous (lay egg) or ovo-viviparous (lays eggs which hatches immediately)
Lives in intestinal tract or tissues.
The name is derived from Greek word,
Trypano means (borer)
Soma means (body)
They are unicellular flagellate protozoa.
Have corkscrew like motion.
Oftenly transmitted by a vector.
Pneumococci are normal commensals of the upper respiratory tract
Important pathogen of pneumonia & otitis media
Reclassified as Streptococcus pneumoniae
Differ from Streptococci in morphology, bile solubility, optochin sensitivity & capsule
Oldest disease known to mankind
First described in ancient Indian
texts as “Kustha roga” attributed ]
to curse from God
Leper : Greek “scaly”
Hansen’s Disease – 1873 Norwegian Armauer Hansen discovered that leprosy is caused by bacterium - Mycobacterium leprae
Albert Neisser (1879) – stained the organism with fuchsin & gentian violet ( AFB )
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).
Largest viruses that infect vertebrates
Can be seen under light microscope
Poxvirus diseases are characterized by skin lesions – localized or generalized
Important diseases caused by poxviruses are-
Smallpox
Monkeypox
Cowpox
Tanapox
Molluscum contagiosum
bacterial Growth curve and nutrition of bacteria.pptNCRIMS, Meerut
The bacterial cell contains water (80% of total weight), proteins, polysaccharides, lipids, nucleic acids, mucopeptides and low molecular weight compounds. For growth and nutrition of bacteria, the minimum nutritional requirements are water, a source of carbon, a source of nitrogen and some inorganic salts.
A type of virus that causes herpes infections and has DNA as its genetic material. There are two types of human herpesviruses. Infections with type 1 viruses cause cold sores on the lips or nostrils. Infections with type 2 viruses cause sores on the genitals (external and internal sex organs and glands).
HPV can cause cervical and other cancers, including cancer of the vulva, vagina, penis, or anus. It can also cause cancer in the back of the throat (called oropharyngeal cancer). This can include the base of the tongue and tonsils. Cancer often takes years, even decades, to develop after a person gets HPV.
polio virus lecture for MBBS
The picornaviruses are small (22 to 30 nm) nonenveloped, single-stranded RNA viruses with cubic symmetry. The virus capsid is composed of 60 protein subunits, each consisting of four poly-peptides VP1–VP4. Because they contain no essential lipids, they are ether resistant. They replicate in the cytoplasm.
Prokaryote cells grow by increasing in cell number (as opposed to increasing in size).
Replication is by BINARY FISSION, the splitting of one cell into two
Therefore, bacterial populations increase by a factor of two (double) every generation time
The time required to for a population to double (doubling time) in number.
Ex. Escherichia coli (E. coli) double every 20 minutes
Ex. Mycobacterium tuberculosis double every 12 to 24 hours
In 1900, Jules Bordet along with Octave Gengou observed a small ovoid bacterium in the sputum of a 5 month old child suffering from pertussis, or whooping cough.
The bacterium was similar to Haemophilus influenza but showed distinct morphological characterstic which led Bordet and Gengou to consider it as a separate species.
The organism was unable to be isolated and cultivated on ordinary blood agar plates.
Six years later, Bordet and Gengou suceed in making a selective media called Bordet and Gengou (BG) medium, which helped in isolating this fastidous bacteria.
this ppt well describes the principle, procedure, modification, usage and limitations of gram's staining.
it is a differential staining method used in bacteriology laboratory
The genus Shigella exclusively infects human intestine.
Shigella dysenteriae is the causative agent of bacillary dysentery or shigellosis in humans.
It is a diarrheal illness which is characterized by frequent passage of blood stained mucopurulent stools.
The four important species of the genus Shigella are:
Shigella dysenteriae
Shigella flexneri
Shigella sonnei
Shigella boydii.
A virus is an obligate intracellular parasite containing genetic material surrounded by protein
Virus particles can only be observed by an electron microscope
Most viruses range in sizes from 20 – 250 nanometers
Protozoa of this group possess one or more whip like flagella as their organs of locomotion
Classification
According to their habitat
Lumen dwelling flagellates
Alimentary canal – Intestinal flagellates
Urogenital tract – Genital flagellattes
2.Hemoflagellates - flagellates found in blood and tissues
Pathogenic:
Intestinal flagellates - Giardia lamblia Duodenum, Jejunum -Diarrhoea.
Genital flagellates - Trichomonas vaginalis Vagina, Urethra -Vaginitis , Urethritis
Non pathogenic:
Trichomonas tenax ( Mouth)
Trichomonas hominis ( Caecum).
Enteromonas hominis ( Colon)
Dientamoeba fragilis( Colon)
DNA molecule is composed of 2 strands of complementary nucleotides bound together by a double Helix.
Bacterial nucleus contains circular chromosome of a double strand DNA molecule of 1000um (1mm) long when straightened.
Each strand have a backbone of deoxyribose sugar and phosphate groups
There are 4 nitrogenous bases
Two purines- adenine(A) and guanine(G)
Two Pyrimidines- thymine(T) and cytosine(C)
One of these four nitrogenous bases is attached to each deoxyribose (sugar)
The two stands are held together by hydrogen bonds between the nitrogenous bases on the opposite strands
R3 Stem Cells and Kidney Repair A New Horizon in Nephrology.pptxR3 Stem Cell
R3 Stem Cells and Kidney Repair: A New Horizon in Nephrology" explores groundbreaking advancements in the use of R3 stem cells for kidney disease treatment. This insightful piece delves into the potential of these cells to regenerate damaged kidney tissue, offering new hope for patients and reshaping the future of nephrology.
CHAPTER 1 SEMESTER V - ROLE OF PEADIATRIC NURSE.pdfSachin Sharma
Pediatric nurses play a vital role in the health and well-being of children. Their responsibilities are wide-ranging, and their objectives can be categorized into several key areas:
1. Direct Patient Care:
Objective: Provide comprehensive and compassionate care to infants, children, and adolescents in various healthcare settings (hospitals, clinics, etc.).
This includes tasks like:
Monitoring vital signs and physical condition.
Administering medications and treatments.
Performing procedures as directed by doctors.
Assisting with daily living activities (bathing, feeding).
Providing emotional support and pain management.
2. Health Promotion and Education:
Objective: Promote healthy behaviors and educate children, families, and communities about preventive healthcare.
This includes tasks like:
Administering vaccinations.
Providing education on nutrition, hygiene, and development.
Offering breastfeeding and childbirth support.
Counseling families on safety and injury prevention.
3. Collaboration and Advocacy:
Objective: Collaborate effectively with doctors, social workers, therapists, and other healthcare professionals to ensure coordinated care for children.
Objective: Advocate for the rights and best interests of their patients, especially when children cannot speak for themselves.
This includes tasks like:
Communicating effectively with healthcare teams.
Identifying and addressing potential risks to child welfare.
Educating families about their child's condition and treatment options.
4. Professional Development and Research:
Objective: Stay up-to-date on the latest advancements in pediatric healthcare through continuing education and research.
Objective: Contribute to improving the quality of care for children by participating in research initiatives.
This includes tasks like:
Attending workshops and conferences on pediatric nursing.
Participating in clinical trials related to child health.
Implementing evidence-based practices into their daily routines.
By fulfilling these objectives, pediatric nurses play a crucial role in ensuring the optimal health and well-being of children throughout all stages of their development.
How many patients does case series should have In comparison to case reports.pdfpubrica101
Pubrica’s team of researchers and writers create scientific and medical research articles, which may be important resources for authors and practitioners. Pubrica medical writers assist you in creating and revising the introduction by alerting the reader to gaps in the chosen study subject. Our professionals understand the order in which the hypothesis topic is followed by the broad subject, the issue, and the backdrop.
https://pubrica.com/academy/case-study-or-series/how-many-patients-does-case-series-should-have-in-comparison-to-case-reports/
One of the most developed cities of India, the city of Chennai is the capital of Tamilnadu and many people from different parts of India come here to earn their bread and butter. Being a metropolitan, the city is filled with towering building and beaches but the sad part as with almost every Indian city
Global launch of the Healthy Ageing and Prevention Index 2nd wave – alongside...ILC- UK
The Healthy Ageing and Prevention Index is an online tool created by ILC that ranks countries on six metrics including, life span, health span, work span, income, environmental performance, and happiness. The Index helps us understand how well countries have adapted to longevity and inform decision makers on what must be done to maximise the economic benefits that comes with living well for longer.
Alongside the 77th World Health Assembly in Geneva on 28 May 2024, we launched the second version of our Index, allowing us to track progress and give new insights into what needs to be done to keep populations healthier for longer.
The speakers included:
Professor Orazio Schillaci, Minister of Health, Italy
Dr Hans Groth, Chairman of the Board, World Demographic & Ageing Forum
Professor Ilona Kickbusch, Founder and Chair, Global Health Centre, Geneva Graduate Institute and co-chair, World Health Summit Council
Dr Natasha Azzopardi Muscat, Director, Country Health Policies and Systems Division, World Health Organisation EURO
Dr Marta Lomazzi, Executive Manager, World Federation of Public Health Associations
Dr Shyam Bishen, Head, Centre for Health and Healthcare and Member of the Executive Committee, World Economic Forum
Dr Karin Tegmark Wisell, Director General, Public Health Agency of Sweden
CHAPTER 1 SEMESTER V PREVENTIVE-PEDIATRICS.pdfSachin Sharma
This content provides an overview of preventive pediatrics. It defines preventive pediatrics as preventing disease and promoting children's physical, mental, and social well-being to achieve positive health. It discusses antenatal, postnatal, and social preventive pediatrics. It also covers various child health programs like immunization, breastfeeding, ICDS, and the roles of organizations like WHO, UNICEF, and nurses in preventive pediatrics.
Antibiotic Stewardship by Anushri Srivastava.pptxAnushriSrivastav
Stewardship is the act of taking good care of something.
Antimicrobial stewardship is a coordinated program that promotes the appropriate use of antimicrobials (including antibiotics), improves patient outcomes, reduces microbial resistance, and decreases the spread of infections caused by multidrug-resistant organisms.
WHO launched the Global Antimicrobial Resistance and Use Surveillance System (GLASS) in 2015 to fill knowledge gaps and inform strategies at all levels.
ACCORDING TO apic.org,
Antimicrobial stewardship is a coordinated program that promotes the appropriate use of antimicrobials (including antibiotics), improves patient outcomes, reduces microbial resistance, and decreases the spread of infections caused by multidrug-resistant organisms.
ACCORDING TO pewtrusts.org,
Antibiotic stewardship refers to efforts in doctors’ offices, hospitals, long term care facilities, and other health care settings to ensure that antibiotics are used only when necessary and appropriate
According to WHO,
Antimicrobial stewardship is a systematic approach to educate and support health care professionals to follow evidence-based guidelines for prescribing and administering antimicrobials
In 1996, John McGowan and Dale Gerding first applied the term antimicrobial stewardship, where they suggested a causal association between antimicrobial agent use and resistance. They also focused on the urgency of large-scale controlled trials of antimicrobial-use regulation employing sophisticated epidemiologic methods, molecular typing, and precise resistance mechanism analysis.
Antimicrobial Stewardship(AMS) refers to the optimal selection, dosing, and duration of antimicrobial treatment resulting in the best clinical outcome with minimal side effects to the patients and minimal impact on subsequent resistance.
According to the 2019 report, in the US, more than 2.8 million antibiotic-resistant infections occur each year, and more than 35000 people die. In addition to this, it also mentioned that 223,900 cases of Clostridoides difficile occurred in 2017, of which 12800 people died. The report did not include viruses or parasites
VISION
Being proactive
Supporting optimal animal and human health
Exploring ways to reduce overall use of antimicrobials
Using the drugs that prevent and treat disease by killing microscopic organisms in a responsible way
GOAL
to prevent the generation and spread of antimicrobial resistance (AMR). Doing so will preserve the effectiveness of these drugs in animals and humans for years to come.
being to preserve human and animal health and the effectiveness of antimicrobial medications.
to implement a multidisciplinary approach in assembling a stewardship team to include an infectious disease physician, a clinical pharmacist with infectious diseases training, infection preventionist, and a close collaboration with the staff in the clinical microbiology laboratory
to prevent antimicrobial overuse, misuse and abuse.
to minimize the developme
Navigating Challenges: Mental Health, Legislation, and the Prison System in B...Guillermo Rivera
This conference will delve into the intricate intersections between mental health, legal frameworks, and the prison system in Bolivia. It aims to provide a comprehensive overview of the current challenges faced by mental health professionals working within the legislative and correctional landscapes. Topics of discussion will include the prevalence and impact of mental health issues among the incarcerated population, the effectiveness of existing mental health policies and legislation, and potential reforms to enhance the mental health support system within prisons.
5. BACTERIOPHAGE
Viruses that infect and parsitized bacteria
is known as bacteriophage.
It was discovered by Frederick.W.Twort in
Great Britian (1915) and Felix d’ Herelle in
France(1917).
D’ Herelle coined the term bacteriophage
meaning ‘bacterial eater’ to describe the
agent’s bacteriocidal activity. He observed
lysis of a broth culture of a dysentry
bacillus.
6. Phages are very simple in structure,
consisting merely of a DNA (or occasionally
ribonucleic acid (RNA)) molecule carrying a
number of genes, surrounded by a protective
coat or capsid made up of protein
molecules.
They can undergo two life cycle
Lytic cycle
Lysogenic cycle
7. Structure of Bacteriophage
•Most of the phages are tadpole-
shaped.
•Phage head: hexagonal in shape,
composed of coat protein and genome in
the core
•Genome: dsDNA codes for enzymes
and proteins necessary to replicate more
viruses
•Tail Sheath: hollow core covered with
a contractile sheath. DNA travels from
head to bacteria through sheath
•Tail fiber: helps anchor the phage on the
cell membrane
•Examples are Lambda phage, M13
phage, T4,T7 phage, P1 phage etc.
8. CHARECTERSTICS OF BACTERIOPHAGES
• Host specificity: they have high host
specificity.
• They are filterable through filters.
• Lytic phage causes lysis of bacteria.
• They are sensitive to heat.
• Their commonest habital is intestinal
bacterial flora of man and animal.
9. PHAGE LIFE CYCLE: LYTIC VS LYSOGENIC
Phage replicates by lytic life cycle
(virulent phage)
•Non-integration of phage genetic material
•Intracellular multiplication of the phage ends in
lysis of host bacterium.
Phage replicates by lysogenic life cycle
(temperate phages (prophages))
•Integration of phage genetic material into
bacterial genome.
•Phage replicates with bacteria causing no harm
to the host cell
10. Adsorption by Lytic Bacteriophage
The bacteriophage binds to specific
receptors on the bacterial cell wall.
Tail conformation changes/contracts
terminal base plate penetrates cell wall
11. An electron micrograph of bacteriophages attached to a bacterial cell. These
viruses are the size and shape of coliphage T1
15. Synthesis of phage component
• Phage-coded enzymes shut down host’s DNA, RNA, protein synthesis.
•Intially, early proteins, including specific enzymes, necessary for
synthesis of phage components are synthesized. During this phase, phage
are not detectable also known as eclipse phase.
•Late functions include the subsequent synthesis of other proteins and
assembly of the nucleocapsid.
-MATURATION
After this the protein subunits of phage head, and tail and phage DNA
assembles to form infective phage particle
16. Phage Release
• A bacteriophage-coded enzyme break down the
peptidoglycan in the bacterial cell wall causing osmotic
lysis.
17.
18. Attachment:
Phage attaches
to host cell.
Penetration:
Phage pnetrates
host cell and
injects its DNA.
Biosynthesis:
Transcription/
Translation and
Viral
chromosome
replication
1
2
3
Bacterial
cell wall
Bacterial
chromosome
Capsid DNA
Capsid
Sheath
Tail fiber
Base plate
Pin
Cell wall
Tail
Plasma membrane
Sheath contracted
Tail core
Lytic Lifecycle of a Bacteriophage I
19. 4 Maturation/Assembly:
Viral components are
assembled into
virions.
Tail
5 Release:
Host cell lyses and
new virions are
released.
DNA
Capsid
Tail fibers
Lytic Lifecycle of a Bacteriophage II
20. LYSOGENIC CONVERSION
The prophage confers certain new properties to
lysogenic bacterium.
Examples: of Lysogenic conversion
* Corynebacterium diphtheria produces the toxin of
diphtheria only when it is infected by the phage β. In this case, the
gene that codes for the toxin is carried by the phage, not the
bacteria.
* Vibrio cholera is a non-toxic strain that can become toxic,
producing cholera toxin, when it is infected with the phage CTXφ.
* Clostridium botulinum causes botulism.
* Streptococcus pyogenes causes scarlet fever.
* Shiga toxin
* Tetanus
21. Bacteriophages Significance
• Phage typing: Used as
epidemiological markers to
identify reservoir of infection.
• Phage therapy: acts as
bacteriocidal agent.
• Acts as a carriers of genes from
one bacterium to another known
as transduction.
• Confers the property of toxin
production in some bacteria.
• Used in studying host- parasite
relationships.
22. TRANSDUCTION
• DNA may be transferred by a
bacteriophage to a bacteria in a
process called transduction.
23. • Phage typing is used as epidemiological marker to
identify different bacterial strains that are
biochemically serologically identical and
indistinguishable from each other.
• Such bacterial strains are differentiated by using
type specific bacteriophage.
• The technique has most extensively been used
for the detection of Mycobacterium tuberculosis,
E.coli, Pseudomonas, Salmonella, Listeria, and
Campylobacter species
24. Bacteriophages in Medicine
• Bacteriophages, or phages, by their
very nature, they can be considered
as potential antibacterial agents.
• Over the past decade or two, the idea
of phage therapy, i.e. the use of lytic
bacteriophages for both the
prophylaxis and the treatment of
bacterial infections, has gained
special significance.
• this leads to the rise in the
prevalence of highly antibiotic-
resistant bacterial strains.
25. Phage Therapy
• Phages were discovered
to be anti-bacterial
agents and were used
throughout the 1940s in
the Soviet Union for
treating bacterial
infections. They had
widespread use including
treating soldiers in the
Red Army. However, they
were abandoned for
general use in the west.
25
27. Limitations of phage therapy
1.Emergence of bacterial strains resistant to
particular phages. The emergence of phage –
resistant bacterial mutants was observed and
the phenomenon was suggested to be a
potential problem of phage therapy
(Summers, 1999; d’Herelle,1930)