What does it mean that viruses are 'obligate intracellular parasites'?
They must enter a host cell and take over its molecular processes to produce more viral particles.
Why do many viruses have a narrow host range?
Because a virus must recognize a specific structure on the cell surface to enter the host cell.
Give the size range examples for the largest and smallest viruses mentioned.
Why were early viruses called 'filterable agents'?
Because they caused disease but passed through the filters of the day and could not be retained by those filters.
Compare the genome sizes of Smallpox and Polio as given.
How do viruses manage with very small genomes?
Viral genes overlap significantly and many proteins have multiple functional sites with different enzymatic activities.
What is a capsid and what is a nucleocapsid?
What nucleic acid forms are found in viruses according to the text?
Nucleic acid can be single-stranded or double-stranded; single-stranded RNA can be plus-strand (resembles mRNA) or minus-strand (complementary to mRNA).
How do enveloped viruses acquire their envelope?
They acquire it from budding out of the host cell membrane, taking a piece of membrane as an envelope.
What advantage does an envelope give a virus regarding the immune system?
Being clothed in a piece of host membrane can help the virus fool the immune system.
Contrast enveloped and naked (non-enveloped) viruses in infectivity and environmental stability.
Enveloped viruses are very infectious but not environmentally tough; naked viruses are environmentally tough but not especially infectious.
What is noted about the fidelity of virus replication?
Virus replication is inherently sloppy, producing many incomplete or badly made particles alongside functional ones.
What is described as the best defense against viral infection?
Vaccination is described as the best defense against viral infection.
What is a common limitation of most recently developed antiviral pharmaceuticals?
They are specific to a small group of viruses and not broad-spectrum.
When are antisera (passive immunity) used for viral infections?
For certain rare but dangerous viral infections.
What is the usual approach to treatment for many viral infections like influenza?
Supportive therapy.
What classification system is generally used to describe viruses by how their nucleic acid produces mRNA?
The Baltimore system.
Which single-stranded DNA virus causes Fifth Disease in humans?
Parvovirus B19.
What is a characteristic clinical sign of Fifth Disease in children?
A 'slapped cheek' rash.
What happens early after Parvovirus B19 infection at the molecular level?
The single strand is copied into double-stranded DNA using a unique polymerase.
What dog disease is mentioned as very dangerous and caused by a parvovirus?
Canine parvovirus is very dangerous for dogs.
Name one feature of Smallpox (Variola) mentioned in the text.
It is highly contagious and enveloped.
Why did Edward Jenner's cowpox inoculation protect against Smallpox?
Because milkmaids who got cowpox did not get Smallpox and Smallpox had only one serotype.
What is the current status of Smallpox as a pathogen according to the text?
It has been eliminated as a pathogen and exists only in research laboratories.
Give one example of a mild poxvirus illness in children mentioned in the text.
Molluscum Contagiosum, which produces small persistent papules.
What outbreak statistics for monkeypox are given in the text?
About 30,000 cases in the U.S. and 20 deaths.
List two shared characteristics of the Herpesviruses mentioned in the text.
Name two additional shared features of Herpesviruses from the text.
How many herpesviruses does the text state exist, and how many will be examined?
There are eight herpesviruses and five will be examined.
What is Human Herpesvirus 1 (HHV1) commonly called?
Herpes Simplex type 1 (oral herpes)
Where does HHV1 persist in the body during latency?
In sensory neurons
What antiviral is mentioned as helpful for HHV1?
Topical acyclovir
What is the typical disease caused by Human Herpesvirus 2 (HHV2)?
Genital herpes
How can oral and genital herpes be definitively distinguished?
By molecular analysis
What disease does Varicella Zoster Virus (VZV) cause initially and what can it re-emerge as?
How is VZV primarily spread during primary infection?
By respiratory droplets
What is the target cell type for Epstein-Barr Virus (HHV4)?
B lymphocytes
Which cancers are associated with HHV4 (Epstein-Barr Virus)?
In which cells does Cytomegalovirus (HHV5) remain latent?
Monocytes and lymphocytes
Name major neonatal complications associated with congenital CMV (HHV5).
Which HHV is called 'sixth disease' and where does it go latent?
HHV6 (roseola infantum) goes latent in T cells
Which herpesvirus is associated with Kaposi's sarcoma and in which cells is it latent?
HHV8 is associated with Kaposi's sarcoma and is latent in B cells
How is Hepatitis B virus (HBV) transmitted?
What unusual feature does the HBV genome have that affects replication?
It is not completely double-stranded and has ragged ends that must be completed using reverse transcriptase
What effect does co-infection with Hepatitis D Virus have on HBV disease severity?
Co-infection with Hepatitis D Virus makes the disease far worse and increases liver cancer risk in severe cases
Is there a vaccine for Hepatitis B virus (HBV)?
Yes, a vaccine is available and has greatly reduced infections
What illnesses can adenovirus cause?
Where can adenovirus establish latency and when is reemergence usually a problem?
It can go latent and reemerge later, usually a problem only in the immunocompromised
What are papillomaviruses (HPV) commonly known to cause?
Warts (often harmless but sometimes unsightly or irritating)
How are genital wart-causing human papillomavirus (HPV) serotypes transmitted?
They are transmitted sexually.
Why can certain HPV serotypes potentially cause cancer?
Because they can incorporate into host chromosomes, creating potential to cause cancer.
Which HPV serotypes are notorious for causing cervical cancer?
Which HPV serotypes cause laryngeal and anogenital warts mentioned in the text?
Which HPV vaccine replaced Cervarix and how many serotypes does it protect against?
Gardasil-9 replaced Cervarix and protects against 9 serotypes.
Which viruses are included in the Polyoma virus group that are highlighted as unusual?
Who should be concerned about Polyoma viruses like BK and JC?
Only immunocompromised individuals should be concerned, as these viruses rarely cause disease.
What does it mean that viruses are 'obligate intracellular parasites'?
They must enter a host cell and take over its molecular processes to produce more viral particles.
Why do many viruses have a narrow host range?
Because a virus must recognize a specific structure on the cell surface to enter the host cell.
Give the size range examples for the largest and smallest viruses mentioned.
Why were early viruses called 'filterable agents'?
Because they caused disease but passed through the filters of the day and could not be retained by those filters.
Compare the genome sizes of Smallpox and Polio as given.
How do viruses manage with very small genomes?
Viral genes overlap significantly and many proteins have multiple functional sites with different enzymatic activities.
What is a capsid and what is a nucleocapsid?
What nucleic acid forms are found in viruses according to the text?
Nucleic acid can be single-stranded or double-stranded; single-stranded RNA can be plus-strand (resembles mRNA) or minus-strand (complementary to mRNA).
How do enveloped viruses acquire their envelope?
They acquire it from budding out of the host cell membrane, taking a piece of membrane as an envelope.
What advantage does an envelope give a virus regarding the immune system?
Being clothed in a piece of host membrane can help the virus fool the immune system.
Contrast enveloped and naked (non-enveloped) viruses in infectivity and environmental stability.
Enveloped viruses are very infectious but not environmentally tough; naked viruses are environmentally tough but not especially infectious.
What is noted about the fidelity of virus replication?
Virus replication is inherently sloppy, producing many incomplete or badly made particles alongside functional ones.
What is described as the best defense against viral infection?
Vaccination is described as the best defense against viral infection.
What is a common limitation of most recently developed antiviral pharmaceuticals?
They are specific to a small group of viruses and not broad-spectrum.
When are antisera (passive immunity) used for viral infections?
For certain rare but dangerous viral infections.
What is the usual approach to treatment for many viral infections like influenza?
Supportive therapy.
What classification system is generally used to describe viruses by how their nucleic acid produces mRNA?
The Baltimore system.
What happens early after Parvovirus B19 infection at the molecular level?
The single strand is copied into double-stranded DNA using a unique polymerase.
What dog disease is mentioned as very dangerous and caused by a parvovirus?
Canine parvovirus is very dangerous for dogs.
Name one feature of Smallpox (Variola) mentioned in the text.
It is highly contagious and enveloped.
Why did Edward Jenner's cowpox inoculation protect against Smallpox?
Because milkmaids who got cowpox did not get Smallpox and Smallpox had only one serotype.
What is the current status of Smallpox as a pathogen according to the text?
It has been eliminated as a pathogen and exists only in research laboratories.
Give one example of a mild poxvirus illness in children mentioned in the text.
Molluscum Contagiosum, which produces small persistent papules.
What outbreak statistics for monkeypox are given in the text?
About 30,000 cases in the U.S. and 20 deaths.
List two shared characteristics of the Herpesviruses mentioned in the text.
Name two additional shared features of Herpesviruses from the text.
How many herpesviruses does the text state exist, and how many will be examined?
There are eight herpesviruses and five will be examined.
What disease does Varicella Zoster Virus (VZV) cause initially and what can it re-emerge as?
Name major neonatal complications associated with congenital CMV (HHV5).
Which HHV is called 'sixth disease' and where does it go latent?
HHV6 (roseola infantum) goes latent in T cells
Which herpesvirus is associated with Kaposi's sarcoma and in which cells is it latent?
HHV8 is associated with Kaposi's sarcoma and is latent in B cells
What unusual feature does the HBV genome have that affects replication?
It is not completely double-stranded and has ragged ends that must be completed using reverse transcriptase
What effect does co-infection with Hepatitis D Virus have on HBV disease severity?
Co-infection with Hepatitis D Virus makes the disease far worse and increases liver cancer risk in severe cases
Is there a vaccine for Hepatitis B virus (HBV)?
Yes, a vaccine is available and has greatly reduced infections
What illnesses can adenovirus cause?
Where can adenovirus establish latency and when is reemergence usually a problem?
It can go latent and reemerge later, usually a problem only in the immunocompromised
What are papillomaviruses (HPV) commonly known to cause?
Warts (often harmless but sometimes unsightly or irritating)
How are genital wart-causing human papillomavirus (HPV) serotypes transmitted?
They are transmitted sexually.
Why can certain HPV serotypes potentially cause cancer?
Because they can incorporate into host chromosomes, creating potential to cause cancer.
Which HPV vaccine replaced Cervarix and how many serotypes does it protect against?
Gardasil-9 replaced Cervarix and protects against 9 serotypes.
Which viruses are included in the Polyoma virus group that are highlighted as unusual?
Who should be concerned about Polyoma viruses like BK and JC?
Only immunocompromised individuals should be concerned, as these viruses rarely cause disease.
Examples: smallpox, cowpox, molluscum contagiosum, monkeypox (recent outbreaks).
Herpesviruses (HHV family) — enveloped, latent, widespread seropositivity; derived from nuclear membrane
Clinical notes: all can establish latency, reactivate, and cause more severe disease in immunocompromised hosts.
Hepadnavirus (Hepatitis B virus, HBV)
Vaccine available and effective; some HIV RT inhibitors are useful against HBV due to similar enzymatic steps.
Adenovirus
Live vaccines for certain serotypes have existed but are not widely used in the general population.
Papillomavirus (HPV)
Vaccines (e.g., Gardasil-9) protect against multiple oncogenic and wart-causing serotypes.
Polyomaviruses (BK, JC, etc.)
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