Lecture 14: Papillomavirus, Adenovirus, Parvovirus - Chap 41, 42, 45 Flashcards
Which virus is associated with warts and cervical cancer?
HPV (Human Papillomavirus)
What do HPV types 16 and 18 increase the risk of?
Cervical, anal, penile, and oropharyngeal cancers
How does HPV evade immune detection?
Hides from immune responses, allowing persistent infection
What cells does HPV primarily infect?
Epithelial cells of skin or mucous membranes
What are the key oncogenes in HPV that promote cell growth?
E6 and E7 proteins
How does HPV affect p53 and RB proteins?
Inactivates them to promote uncontrolled cell growth
What is the common symptom of HPV infection on the skin?
Benign warts
How is HPV commonly transmitted?
By direct or sexual contact, and fomites
Which method is used for HPV detection in clinical settings?
PCR genome analysis of cervical swabs
Which HPV types are targeted by available vaccines?
Types 6, 11, 16, 18, 31, 33, 45, 52, and 58
What virus is linked to Merkel cell carcinoma?
MCPyV (Merkel Cell Polyomavirus)
What disease does JCV cause in immunocompromised individuals?
Progressive multifocal leukoencephalopathy (PML)
How is JCV transmitted?
Inhalation or contact with contaminated water or saliva
What type of cells are affected in JCV-associated PML?
Astrocytes and oligodendrocytes
What is a distinguishing characteristic of PML lesions?
Demyelination with large abnormal astrocytes and oligodendrocytes
How is PML diagnosed in patients suspected of JCV infection?
PCR detection of viral DNA in cerebrospinal fluid and MRI/CT scans
What organ is primarily affected by BK virus in immunocompromised individuals?
Kidneys
How do polyomaviruses, such as BK virus, maintain persistent infection?
Establish latent infection in organs like kidneys and lungs
Which proteins do both HPV and polyomaviruses use to disrupt cell cycle regulation?
T antigen (in polyomaviruses) and E6/E7 proteins (in HPV)
What method is ineffective for polyomavirus control and treatment?
No effective mode of control is currently available
How does HPV tissue tropism vary by type?
Specific HPV types infect different tissues and determine disease manifestation
Which polyomavirus is commonly associated with kidney disease?
BK virus
What triggers reactivation of JCV and BK virus?
Immunocompromised state
Why are JCV infections usually asymptomatic in early life?
The virus remains latent and does not cause symptoms in healthy individuals
In which population are both HPV and polyomaviruses a significant health concern?
Immunocompromised individuals
What does CIN stand for in relation to HPV infection?
Cervical Intraepithelial Neoplasia
How do HPV infections typically resolve?
Slowly and often spontaneously due to immune response
What is the main transmission method for HPV laryngeal papillomas?
Passage through an infected birth canal (Types 6 and 11)
How is HPV distributed worldwide?
Ubiquitously, with no seasonal incidence
Why does JCV infection lead to progressive neurological symptoms?
Due to demyelination and damage to brain cells
Which two types of polyomaviruses are specifically noted for opportunistic disease?
JCV and BK virus
Why are warts common with HPV infection?
Caused by benign outgrowth of infected epithelial cells
What demographic factor increases the risk of BK virus-related kidney disease?
Immunosuppression (e.g., transplant patients)
What type of genome do papillomaviruses and polyomaviruses have?
DNA genome
How would you describe the capsid structure of papillomaviruses?
Small, naked capsid
What is the significance of a ‘naked capsid’ in virus structure?
Resistant to environmental stress, aids in transmission
Which proteins are key for HPV’s ability to manipulate the host cell cycle?
E6 and E7 proteins
What role does the T antigen play in polyomaviruses?
Inactivates p53 and RB to promote cell growth
How does the HPV genome influence its tissue tropism?
Specific HPV types target different epithelial tissues
Where does HPV persist in the body during infection?
Basal layer of skin or mucous membranes
What is the genome type of polyomaviruses like JCV and BK?
DNA genome
What is a key feature of the HPV genome in terms of immune evasion?
Remains hidden from immune system
How does JCV affect the brain in immunocompromised patients?
Causes demyelination by damaging brain cells
What is the structure of HPV genome?
Double-stranded circular DNA genome
What HPV protein binds origin and helps increase transcription?
E1 protein
Which HPV protein helps with the release of virions?
E4 protein
Which protein is responsible for EGFR activation in HPV?
E5 protein
What are the structural capsid proteins in HPV?
L1 and L2
Describe the genome structure of adenovirus.
Linear double-stranded DNA
What unique feature does adenovirus capsid have?
Icosahedral capsid with fibers at vertices
What genome structure does parvovirus have?
Single-stranded linear DNA
What key function does HPV’s E6 protein serve in oncogenesis?
Binds p53, activates telomerase, suppresses apoptosis
How does E7 protein promote cancer in HPV?
Binds to p105RB, promoting cell cycle progression
What proteins in polyomavirus help regulate early and late gene transcription?
Large T antigen
Which polyomavirus protein is a major capsid and attachment protein?
VP1
What is the main disease mechanism in parvovirus B19 infection?
Infects erythroid precursor cells, causing lytic infection
What does CIN1 represent in HPV infection?
Mild changes affecting 1/3 of cervical layer
Describe CIN2 in HPV infection.
Moderate changes affecting 2/3 of cervical layer
What is CIN3 in HPV pathology?
Severe changes affecting full cervical layer, not yet cancer
What is progressive multifocal leukoencephalopathy (PML)?
A JCV-caused demyelinating disease in immunocompromised individuals
What condition can adenovirus cause in crowded environments like camps?
Pharyngoconjunctival fever
How is HPV typically transmitted?
Direct and sexual contact, birth canal for types 6 and 11
How is adenovirus transmitted?
Respiratory droplets, fecal-oral route, contaminated surfaces
What age group is most at risk for parvovirus B19?
Children in elementary school
Which demographic is at risk for severe B19 complications?
Non-immune pregnant women and those with chronic anemia
Who is at risk for PML with JCV reactivation?
Immunocompromised patients
What age group is often affected by adenovirus in crowded settings?
Children under 14
What diagnostic test is commonly used for HPV?
PCR genome analysis
How is PML diagnosed in suspected JCV infection?
PCR on cerebrospinal fluid, MRI or CT for lesions
What diagnostic method is used for adenovirus typing?
PCR of respiratory or fecal samples
How is parvovirus B19 infection confirmed?
PCR or IgM antibody test
What vaccine protects against multiple HPV types?
Gardasil 9
What HPV types are included in Gardasil 9?
Types 6, 11, 16, 18, 31, 33, 45, 52, 58
Is there a vaccine for adenovirus?
Yes, for military use covering types 4 and 7
How is parvovirus B19 infection typically controlled?
No specific treatment; managed with supportive care
What type of immune response is crucial for clearing parvovirus B19?
Antibody response
What is a control method for adenovirus in shared environments?
Good hygiene and disinfection of contaminated surfaces
How would you describe the virus structure of Parvovirus?
naked icoshedsral capsid
single stranded (+ or - sense) dna genome
What is the genome type of Papillomaviruses (HPV)?
Double-stranded circular DNA
What structural proteins form the capsid of HPV?
L1 and L2 proteins
How does HPV primarily achieve cell transformation?
Through E6 and E7 proteins binding to p53 and p105RB
Describe the lifecycle of HPV in keratinocytes.
HPV infects basal cells, persists in basal layer, replicates in differentiating keratinocytes, releases virions in the outer layers
What diseases are associated with high-risk HPV types like HPV-16 and HPV-18?
Cervical cancer, other anogenital cancers
How does HPV evade the immune response?
Persistence in the basal layer, hiding from immune detection
Describe the typical presentation of common warts caused by HPV.
Flesh-colored, scaly papules, often on hands and feet
What is the main diagnostic test for identifying HPV infections?
PCR for HPV typing, Pap smear for cellular changes
What vaccines are available for HPV prevention?
Gardasil (covers types 6, 11, 16, 18) and Gardasil 9 (covers 9 types)
What is the structure of Adenovirus?
Non-enveloped, icosadeltahedral capsid with fibers
What genome type is found in Adenoviruses?
Linear double-stranded DNA
How do Adenovirus fibers contribute to infection?
Act as viral attachment proteins for host cell entry
Describe the Adenovirus lifecycle.
1) Entry via receptor-mediated endocytosis, 2) DNA replication in nucleus, 3) Assembly and release by cell lysis
Which infections are commonly caused by Adenoviruses?
Respiratory infections, conjunctivitis, gastroenteritis
How does Adenovirus spread among hosts?
Aerosols, direct contact, fecal-oral route, and contaminated surfaces
What age group is most commonly affected by Adenovirus infections?
Children under 14 years, especially in crowded areas
Which diagnostic method is commonly used for Adenovirus infections?
PCR for viral DNA, cell culture for isolation
How is Adenovirus controlled in high-risk settings like military camps?
Live oral vaccines for serotypes 4 and 7 are used for military personnel
What type of genome does Parvovirus B19 have?
Single-stranded linear DNA
Why does Parvovirus B19 need mitotically active cells for replication?
It lacks polymerase and relies on host cell division machinery
Describe the lifecycle of Parvovirus B19.
1) Infects erythroid precursor cells, 2) Replicates in nucleus, 3) Released by cell lysis
What condition is associated with Parvovirus B19 infection in children?
Erythema infectiosum (Fifth disease) with ‘slapped-cheek’ rash
Which populations are at increased risk of severe disease with Parvovirus B19 infection?
Immunocompromised individuals, pregnant women, individuals with chronic anemia
How is Parvovirus B19 primarily transmitted?
Respiratory droplets and oral secretions
What are the clinical symptoms of Parvovirus B19 in adults?
Joint pain (arthralgia), fatigue, mild flu-like symptoms
How can Parvovirus B19 infection be diagnosed?
Serology for IgM antibodies, PCR for viral DNA
Why is quarantine not effective in preventing Parvovirus B19 spread?
Contagious period precedes symptom onset
What is the biphasic nature of Parvovirus B19 disease?
Initial viremia with flu-like symptoms, followed by immune response causing rash and joint pain
Describe the main prevention strategy for HPV transmission.
Vaccination, safe sexual practices, and screening programs
What treatment is recommended for Parvovirus B19 in immunocompromised patients?
IV-IgG therapy to boost antibody response
How does Parvovirus B19 infection affect pregnancy?
Risk of fetal anemia and hydrops fetalis
What role do HPV E6 and E7 proteins play in oncogenesis?
E6 binds p53, preventing apoptosis; E7 binds p105RB, promoting cell cycle progression
In what form does HPV persist in infected cells?
As episomal DNA in the nucleus of basal epithelial cells
How does Adenovirus evade immune detection during infection?
Encodes proteins that inhibit MHC I presentation and TNF-α response
What environmental factors make Adenovirus highly transmissible?
Resistance to drying, detergents, and gastrointestinal conditions
How is Parvovirus B19’s lack of polymerase significant in its replication?
It must infect dividing cells to replicate, often affecting erythroid precursor cells
