Lesson 5. Part 2 (COMPLETE)

Vertical Transmission

TYPES OF TRANSMISSION:

• through generations

• from pregnant mother to embryo or from mother to baby via breastmilk

Horizontal Transmission

TYPES OF TRANSMISSION:

• from one individual to another of the same species and they are not in a parent-child relationship

via droplet nuclues

MODES OF TRANSMISSION:

• particles expelled into the atmosphere during sneezing, coughing, or talking

influenza, common cold, measles and other viruses infecting the respiratory system

examples of diseases transmitted via droplet nuclei

mucus-coated

When it is transmitted via droplet nuclei, it is a ____________ droplet

humidity

The ease of transmission via droplet nuclei is dependent on ____________.

low humidity

When it is transmitted via droplet nuclei, _________ means that the mucus rapidly dries so the aerosolized particle becomes lighter and remains suspended in the air for longer.

fecal-oral route

MODES OF TRANSMISSION:

• common means of transmission for viruses whose primary infection site is the gastrointestinal tract or associated organs

hepatitis A and polio

examples of diseases transmitted in the fecal-oral route

via sexual intercourse

MODES OF TRANSMISSION;

• ex: HIV/AIDS, hepatitis b, genital herpes, and cervical cancer

insect vectors

MODES OF TRANSMISSION:

• ex: dengue fever virus, West Nile disease and tickborne encephalitis

direct contact with infected patients or contaminated objects

MODES OF TRANSMISSION:

• introduction onto the skin, for example warts and verrucae

• into the blood stream by skin damage following scratching, for example pox viruses

direct introduction into the blood stream

MODES OF TRANSMISSION:

• hepatitis B from contaminated syringe and needles

• rabies following animal bites

reproduce

VIRUSES’ CHARACTERISTICS:

• cannot ________________ on their own

metabolism

VIRUSES’ CHARACTERISTICS:

• no ___________

proteins, lipids, or nucleic acids

VIRUSES’ CHARACTERISTICS:

• cannot synthesize their own ____________________________

intracellular

VIRUSES’ CHARACTERISTICS:

• true _______________ parasites that grow within living cells and use their energy and synthetic machinery to produce viral components

cell death

VIRUSES’ CHARACTERISTICS:

• production and excision from the host cell will result in _______, although not immediate

hundreds of new viruses

VIRUSES’ CHARACTERISTICS:

• replication of one virus will result to ______________ (virus progeny or virions)

viral disease

VIRUSES’ CHARACTERISTICS:

• defined as the propagation from one infected cell to new cells and the subsequent destruction of tissue or cells

destruction

VIRUS-HOST CELL INTERACTIONS:

A. multiplication of the virus and ________ of the host cell upon release of the viral progeny

STEPS:

1. A _________ enters a cell

2. Substances in the cell begin to strip off the virus’s ___________________

3. The ________ in the center of the virus is released

4. The nucleic acid gets into the cell’s___________________________.

5. The cell “ignores” its own chemical needs and switches to __________________.

6. The cell is sometimes destroyed in the process. Many of the new viruses are released to _________ other cells.

A = ?

virus

VIRUS-HOST CELL INTERACTIONS:

A. multiplication of the virus and ________ of the host cell upon release of the viral progeny

STEPS:

1. A _________ enters a cell

2. Substances in the cell begin to strip off the virus’s ___________________

3. The ________ in the center of the virus is released

4. The nucleic acid gets into the cell’s___________________________.

5. The cell “ignores” its own chemical needs and switches to __________________.

6. The cell is sometimes destroyed in the process. Many of the new viruses are released to _________ other cells.

1 = ?

outer coat of protein

VIRUS-HOST CELL INTERACTIONS:

A. multiplication of the virus and ________ of the host cell upon release of the viral progeny

STEPS:

1. A _________ enters a cell

2. Substances in the cell begin to strip off the virus’s ___________________

3. The ________ in the center of the virus is released

4. The nucleic acid gets into the cell’s___________________________.

5. The cell “ignores” its own chemical needs and switches to __________________.

6. The cell is sometimes destroyed in the process. Many of the new viruses are released to _________ other cells.

2 = ?

nucleic acid

VIRUS-HOST CELL INTERACTIONS:

A. multiplication of the virus and ________ of the host cell upon release of the viral progeny

STEPS:

1. A _________ enters a cell

2. Substances in the cell begin to strip off the virus’s ___________________

3. The ________ in the center of the virus is released

4. The nucleic acid gets into the cell’s___________________________.

5. The cell “ignores” its own chemical needs and switches to __________________.

6. The cell is sometimes destroyed in the process. Many of the new viruses are released to _________ other cells.

3 = ?

chemical manufacturing system

VIRUS-HOST CELL INTERACTIONS:

A. multiplication of the virus and ________ of the host cell upon release of the viral progeny

STEPS:

1. A _________ enters a cell

2. Substances in the cell begin to strip off the virus’s ___________________

3. The ________ in the center of the virus is released

4. The nucleic acid gets into the cell’s___________________________.

5. The cell “ignores” its own chemical needs and switches to __________________.

6. The cell is sometimes destroyed in the process. Many of the new viruses are released to _________ other cells.

4 = ?

making new viruses

VIRUS-HOST CELL INTERACTIONS:

A. multiplication of the virus and ________ of the host cell upon release of the viral progeny

STEPS:

1. A _________ enters a cell

2. Substances in the cell begin to strip off the virus’s ___________________

3. The ________ in the center of the virus is released

4. The nucleic acid gets into the cell’s___________________________.

5. The cell “ignores” its own chemical needs and switches to __________________.

6. The cell is sometimes destroyed in the process. Many of the new viruses are released to _________ other cells.

5 = ?

infect

VIRUS-HOST CELL INTERACTIONS:

A. multiplication of the virus and ________ of the host cell upon release of the viral progeny

STEPS:

1. A _________ enters a cell

2. Substances in the cell begin to strip off the virus’s ___________________

3. The ________ in the center of the virus is released

4. The nucleic acid gets into the cell’s___________________________.

5. The cell “ignores” its own chemical needs and switches to __________________.

6. The cell is sometimes destroyed in the process. Many of the new viruses are released to _________ other cells.

6 = ?

release

VIRUS-HOST CELL INTERACTIONS:

B. multiplication of the virus and ___________ of the virions without the immediate destruction of the host cell

1. Attachment: The Influenza virus becomes attached to a target ____________.

2. Penetration: The cell engulfs the virus by _____________.

3. Uncoating: ______________ are released.

4. Release: New viral particles are made and released into the _____________. The cell, which is not killed in the process, continues to make new virus.

5. Assembly: New ______________ are assembled.

6. Biosynthesis: Viral RNA enters the nucleus, where it is replicated by the viral ___________________.

B = ?

epithelial cell

VIRUS-HOST CELL INTERACTIONS:

B. multiplication of the virus and ___________ of the virions without the immediate destruction of the host cell

1. Attachment: The Influenza virus becomes attached to a target ____________.

2. Penetration: The cell engulfs the virus by _____________.

3. Uncoating: ______________ are released.

4. Release: New viral particles are made and released into the _____________. The cell, which is not killed in the process, continues to make new virus.

5. Assembly: New ______________ are assembled.

6. Biosynthesis: Viral RNA enters the nucleus, where it is replicated by the viral ___________________.

1 = ?

endocytosis

VIRUS-HOST CELL INTERACTIONS:

B. multiplication of the virus and ___________ of the virions without the immediate destruction of the host cell

1. Attachment: The Influenza virus becomes attached to a target ____________.

2. Penetration: The cell engulfs the virus by _____________.

3. Uncoating: ______________ are released.

4. Release: New viral particles are made and released into the _____________. The cell, which is not killed in the process, continues to make new virus.

5. Assembly: New ______________ are assembled.

6. Biosynthesis: Viral RNA enters the nucleus, where it is replicated by the viral ___________________.

2 = ?

Viral contents

VIRUS-HOST CELL INTERACTIONS:

B. multiplication of the virus and ___________ of the virions without the immediate destruction of the host cell

1. Attachment: The Influenza virus becomes attached to a target ____________.

2. Penetration: The cell engulfs the virus by _____________.

3. Uncoating: ______________ are released.

4. Release: New viral particles are made and released into the _____________. The cell, which is not killed in the process, continues to make new virus.

5. Assembly: New ______________ are assembled.

6. Biosynthesis: Viral RNA enters the nucleus, where it is replicated by the viral ___________________.

3 = ?

extracellular fluid

VIRUS-HOST CELL INTERACTIONS:

B. multiplication of the virus and ___________ of the virions without the immediate destruction of the host cell

1. Attachment: The Influenza virus becomes attached to a target ____________.

2. Penetration: The cell engulfs the virus by _____________.

3. Uncoating: ______________ are released.

4. Release: New viral particles are made and released into the _____________. The cell, which is not killed in the process, continues to make new virus.

5. Assembly: New ______________ are assembled.

6. Biosynthesis: Viral RNA enters the nucleus, where it is replicated by the viral ___________________.

4 = ?

phage particles

VIRUS-HOST CELL INTERACTIONS:

B. multiplication of the virus and ___________ of the virions without the immediate destruction of the host cell

1. Attachment: The Influenza virus becomes attached to a target ____________.

2. Penetration: The cell engulfs the virus by _____________.

3. Uncoating: ______________ are released.

4. Release: New viral particles are made and released into the _____________. The cell, which is not killed in the process, continues to make new virus.

5. Assembly: New ______________ are assembled.

6. Biosynthesis: Viral RNA enters the nucleus, where it is replicated by the viral ___________________.

5 = ?

RNA polymerase

VIRUS-HOST CELL INTERACTIONS:

B. multiplication of the virus and ___________ of the virions without the immediate destruction of the host cell

1. Attachment: The Influenza virus becomes attached to a target ____________.

2. Penetration: The cell engulfs the virus by _____________.

3. Uncoating: ______________ are released.

4. Release: New viral particles are made and released into the _____________. The cell, which is not killed in the process, continues to make new virus.

5. Assembly: New ______________ are assembled.

6. Biosynthesis: Viral RNA enters the nucleus, where it is replicated by the viral ___________________.

6 = ?

latent

VIRUS-HOST CELL INTERACTIONS:

C. survival of the virus in a _______ stage without noticeable changes to the infected cell

altered or transformed

VIRUS-HOST CELL INTERACTIONS:

D. survival of the infected cell in a dramatically ____________ state (transformation of a normal cell to one having the properties of a cancerous cell)

incorporation

VIRUS-HOST CELL INTERACTIONS:

E. __________ of the viral nucleic acid in the host cell genome without noticeable changes to the infected cell

CMV in children

VIRAL INFECTIONS:

1. asymptomatic or silent

2. mild symptoms

3. kill the host

4. range of symptoms

5. not cause immediate symptoms but will lead to an incurable disease

1 = ?

rhinoviruses

VIRAL INFECTIONS:

1. asymptomatic or silent

2. mild symptoms

3. kill the host

4. range of symptoms

5. not cause immediate symptoms but will lead to an incurable disease

2 = ?

ebola virus

VIRAL INFECTIONS:

1. asymptomatic or silent

2. mild symptoms

3. kill the host

4. range of symptoms

5. not cause immediate symptoms but will lead to an incurable disease

3 = ?

SARS-Cov-2 virus

VIRAL INFECTIONS:

1. asymptomatic or silent

2. mild symptoms

3. kill the host

4. range of symptoms

5. not cause immediate symptoms but will lead to an incurable disease

4 = ?

HIV

VIRAL INFECTIONS:

1. asymptomatic or silent

2. mild symptoms

3. kill the host

4. range of symptoms

5. not cause immediate symptoms but will lead to an incurable disease

5 = ?

Attachment to the Host Cell

Step 1 of Multiplication of Human Viruses

Brownian motion

ATTACHMENT TO THE HOST CELLS (STEPS):

1. Initial contact dependent on ______________

2. ___________________ during which electrostatic repulsion is reduced

3. ___________________ in virus-receptor-host-receptor configuration that initiates viral penetration through the cell membrane

1 = ?

Reversible phase

ATTACHMENT TO THE HOST CELLS (STEPS):

1. Initial contact dependent on ______________

2. ___________________ during which electrostatic repulsion is reduced

3. ___________________ in virus-receptor-host-receptor configuration that initiates viral penetration through the cell membrane

2 = ?

Irreversible changes

ATTACHMENT TO THE HOST CELLS (STEPS):

1. Initial contact dependent on ______________

2. ___________________ during which electrostatic repulsion is reduced

3. ___________________ in virus-receptor-host-receptor configuration that initiates viral penetration through the cell membrane

3 = ?

Viral receptors (glycoproteins)

Recognize and bind receptors on the host cells and provide the virus with its high specificity

Penetration of the Viral Particles

Step 2 of Multiplication of Human Viruses

Endocytosis

PENETRATION OF THE VIRAL PARTICLES:

• cell brings external materials into itself by engulfing them with its cell membrane, which then pinches off to form a vesicle or vacuole

• virus-host-receptor interaction triggers the cell membrane to engulf the virus particle, forming a cystosolic vacuole

for non-enveloped but with few enveloped viruses

ex of viruses that undergoes endocytosis

Fusion

PENETRATION OF THE VIRAL PARTICLE:

• happens to their envelope with the host-cell membrane, liberating the viral capsid within the cell cytoplasm

enveloped viruses

ex of viruses that undergoes fusion

Injection

PENETRATION OF THE VIRAL PARTICLE:

• for bacteriophage which infects bacteria by contracting their tail to inject DNA through the bacterial wall and membrane

Uncoating of the Viral Particle

Step 3 of Multiplication of Human Viruses

nucleic acid

UNCOATING OF THE VIRAL PARTICLE:

1. Release of the _______________ from the capsid

2. (a._____________) acidification of the cytosolic vacuoles following endosome fusion induces a conformational change in the capsid and the release of viral b._________ (helper proteins plus nucleic acid) into the cytoplasm

3. Partial uncoating () might also happen

1 = ?

endocytosis

UNCOATING OF THE VIRAL PARTICLE:

1. Release of the _______________ from the capsid

2. (a._____________) acidification of the cytosolic vacuoles following endosome fusion induces a conformational change in the capsid and the release of viral b._________ (helper proteins plus nucleic acid) into the cytoplasm

3. Partial uncoating (_________________) might also happen

2.a. = ?

nucleocapsid

UNCOATING OF THE VIRAL PARTICLE:

1. Release of the _______________ from the capsid

2. (a._____________) acidification of the cytosolic vacuoles following endosome fusion induces a conformational change in the capsid and the release of viral b._________ (helper proteins plus nucleic acid) into the cytoplasm

3. Partial uncoating (_______________) might also happen

2.b. = ?

reovirus

UNCOATING OF THE VIRAL PARTICLE:

1. Release of the _______________ from the capsid

2. (a._____________) acidification of the cytosolic vacuoles following endosome fusion induces a conformational change in the capsid and the release of viral b._________ (helper proteins plus nucleic acid) into the cytoplasm

3. Partial uncoating (_____________) might also happen

3 = ?

Replication of the Nucleic Acids and Translation of the Genome

Step 4 of Multiplication of Human Viruses

Viral Replication

Replication of the Nucleic Acids and Translation of the Genome

• ensures that the host cell synthesis machinery is taken over by the virus and the viral genome is replicated

viral mRNa

MECHANISM OF VIRAL REPLICATION:

1. Transcription of viral genes into ____________

2. Translation of the viral genome into _________

3. Replication of the _____________

1 = ?

proteins

MECHANISM OF VIRAL REPLICATION:

1. Transcription of viral genes into ____________

2. Translation of the viral genome into _________

3. Replication of the _____________

2 = ?

viral genome

MECHANISM OF VIRAL REPLICATION:

1. Transcription of viral genes into ____________

2. Translation of the viral genome into _________

3. Replication of the _____________

3 = ?

Transcription

the process by which genetic information in DNA or RNA is copied into messenger RNA (mRNA).

• DNA → mRNA

• RNA → mRNA

Translation

the process by which the mRNA is read by ribosomes (of the hijacked host cell) to make proteins.

• mRNA → Proteins

release of nucleocapsid

Transcription and Translation:

a. occur immediately after the ____________________ in to the cytoplasm

ensures:

b. production of early proteins such as _______________

c. hijacking of the _________________ machinery

a = ?

viral polymerases

Transcription and Translation:

a. occur immediately after the ____________________ in to the cytoplasm

ensures:

b. production of early proteins such as _______________

c. hijacking of the _________________ machinery

b = ?

cell synthesis

Transcription and Translation:

a. occur immediately after the ____________________ in to the cytoplasm

ensures:

b. production of early proteins such as _______________

c. hijacking of the _________________ machinery

c = ?

type of nucleic acid

REPLICATION OF THE NUCLEIC ACIDS AND TRANSLATION OF THE GENOME:

1. Replication depends on the _________________ carried by the virus

2. Viral mRNA: __________; several distinct proteins are encoded within a single piece of mRNA

3. Virus needs to use a virus-specific __________ to cut at the correct place the polyprotein produced by translation to restore the functionality of viral proteins

1 = ?

polycistronic

REPLICATION OF THE NUCLEIC ACIDS AND TRANSLATION OF THE GENOME:

1. Replication depends on the _________________ carried by the virus

2. Viral mRNA: __________; several distinct proteins are encoded within a single piece of mRNA

3. Virus needs to use a virus-specific __________ to cut at the correct place the polyprotein produced by translation to restore the functionality of viral proteins

2 = ?

protease

REPLICATION OF THE NUCLEIC ACIDS AND TRANSLATION OF THE GENOME:

1. Replication depends on the _________________ carried by the virus

2. Viral mRNA: __________; several distinct proteins are encoded within a single piece of mRNA

3. Virus needs to use a virus-specific __________ to cut at the correct place the polyprotein produced by translation to restore the functionality of viral proteins

3 = ?

positive strand RNA (poliovirus)

REPLICATION PROCESS:

• used directly as mRNA following the acquisition of a terminal sequence from the host cell

negative strand RNA (influenza virus)

REPLICATION PROCESS:

• transcribed into a positive RNA using an RNA-dependent RNA polymerase carried by the virus

ds DNA viruses (adenoviruses)

REPLICATION PROCESS:

• nucleic acid passes into the nucleus, where it is usually transcribed by a host DNA-dependent RNA polymerase

• Poxvirus - the enzyme is contained within the virus, allowing the relocation in the cytoplasm

SS RNA (HIV)

REPLICATION PROCESS:

• reverse transcribed to a ss proviral DNA by reverse transcriptase

• Acts both as an RNA and DNA directed DNA polymerase

• Has RNAase activity

• Proviral DNA can be transported to the cell nucleus where it can be integrated within the cell host genome by a viral integrase

Maturation or Assembly of Virions

Step 5 of Multiplication of Human Viruses

structural proteins

Maturation or Assembly of Virions

1. viral capsid starts to form from individual __________________

2. replicated viral genome and some viral proteins become packaged within the _______ (cytoplasm or in the cell nucleus)

3. (enveloped) envelope originates from the __________

4. presence of _____________________ may play an important role in the interaction of the nucleic acid and the structural proteins

1 = ?

capsid

Maturation or Assembly of Virions

1. viral capsid starts to form from individual __________________

2. replicated viral genome and some viral proteins become packaged within the _______ (cytoplasm or in the cell nucleus)

3. (enveloped) envelope originates from the __________

4. presence of _______________ may play an important role in the interaction of the nucleic acid and the structural proteins

2 = ?

host

Maturation or Assembly of Virions

1. viral capsid starts to form from individual __________________

2. replicated viral genome and some viral proteins become packaged within the _______ (cytoplasm or in the cell nucleus)

3. (enveloped) envelope originates from the __________

4. presence of _______________ may play an important role in the interaction of the nucleic acid and the structural proteins

3 = ?

chaperone proteins

Maturation or Assembly of Virions

1. viral capsid starts to form from individual __________________

2. replicated viral genome and some viral proteins become packaged within the _______ (cytoplasm or in the cell nucleus)

3. (enveloped) envelope originates from the __________

4. presence of ___________________ may play an important role in the interaction of the nucleic acid and the structural proteins

4 = ?

Release of Virions into the Surrounding Environment

Step 6 of Multiplication of Human Viruses

mature virions

Release of Virions into the Surrounding Environment:

• _____________________ are released from the host cell

budding process

Release of Virions into the Surrounding Environment:

• Enveloped Viruses are released by a ________________________ in which the Host cell will die following damage to its metabolism and housekeeping functions during viral replication

cell lysis

Release of Virions into the Surrounding Environment:

a. Non-enveloped Virus progeny accumulates within the host cell cytoplasm and is released following ______________.

b. Viruses (bacteriophages) produce a ______________________________ to lyse (causing a bursting) the host, enabling the release of infectious particles

c. Host _________________ as it cannot maintain normal housekeeping functions during viral infection

a = ?

lytic enzyme (peptide) or proteases

Release of Virions into the Surrounding Environment:

a. Non-enveloped Virus progeny accumulates within the host cell cytoplasm and is released following ______________.

b. Viruses (bacteriophages) produce a ______________________________ to lyse (causing a bursting) the host, enabling the release of infectious particles

c. Host ____________________ as it cannot maintain normal housekeeping functions during viral infection

b = ?

self-disintegrates

Release of Virions into the Surrounding Environment:

a. Non-enveloped Virus progeny accumulates within the host cell cytoplasm and is released following ______________.

b. Viruses (bacteriophages) produce a ______________________________ to lyse (causing a bursting) the host, enabling the release of infectious particles

c. Host ________________ as it cannot maintain normal housekeeping functions during viral infection

c = ?

Cell Culture

• first way to cultivate viruses

• needs living cells organisms as it needs a host to multiply

Primary

CELL CULTURE:

• diploid cell lines

• derived directly from an intact tissue such as human embryo kidney or monkey kidney

Secondary

CELL CULTURE:

• diploid cell lines

• derived from primary cultures, usually from embryonic tissu

• More homogenous, better characterized, but might not be as susceptible to viral infection as primary cell lines

• Limited subcultures can be performed up to a max of about 50 before cells degenerate

• have a property called contact inhibition

Contact Inhibition

property that once the culture comes into contact with the edges of the petri dish they stop multiplying

Continuous

CELL CULTURE:

• derived from malignant tissue (HeLa cells derived from a cervical carcinoma)

• have the capacity to multiply indefinitely in vitro (no contact inhibition)

Vaccine Production

• obtained from an approved cell bank

• need to be checked for infectious and tumorigenicity (in case of live vaccines)

fertile chicken eggs (9-11 days old)

Chick embryo are ________________________.

Chick embryo

used as a convenient cell system to grow human pathogenic viruses

Chorioallantoic membrane, amniotic, yolk sac, and allantoic inoculation

Chick Embryo

• there are many types of different tissues (____________________________) found on eggs, will support growth of different viruses

expensive

Chick embryo is _______________ and should be free from specific pathogens and originate from healthy flock.

aseptic conditions

Processing of fertilized egg (Chick Embryo) must be conducted under ________________ in area where no other infectious agents or cells are handled at the same time.

rodents and primates

examples of animal inoculation

Animal Inoculation

• to study antiviral and vaccine effectiveness

• source of cell lines for cell culture

• follows strict ethical guidelines and is extremely expensive

• must be free from diseases

• growth of the virus is indicated by signs of disease or death