Virology and Infections Quiz

Clinical Virology

• Focuses on various viruses and their clinical implications.
• Covers different virus types (DNA, RNA, etc.) and their associated diseases.
• Includes information on pathogenesis, clinical syndromes, treatment, prevention, and control.

DNA Virus: Papillomavirus

• At least 100 types identified.
• Naked double-stranded DNA virus.
• Can be cutaneous or mucosal.
• A group associated with mucosal HPV is linked to cervical cancer.
• HPV genome is circular and has approximately 8,000 base pairs.
• HPV DNA encodes early genes (E1 to E8) and late/structural genes (L1 and L2).
• Viral pathogenesis includes inoculation, local multiplication, wart formation, and potential cell transformation.
• Clinical syndromes include warts (benign, self-limited skin proliferations), oral papillomas (benign epithelial oral tumors), and laryngeal papillomas (common benign epithelial head and neck tumors).
• Anogenital warts (condylomata acuminata) are almost exclusively on the squamous epithelium of the external genitalia and perianal regions, caused by HPV 6 and 11.
• Cervical dysplasia/neoplasia associated with high-risk HPV types (HPV 16 and 18) can cause cervical neoplasia and cancer.
• Mild dysplasia often spontaneously regresses (approximately 40-70%).

DNA Virus: Polyomavirus

• Includes BK, JC, and SV40 viruses.
• Acquired by respiratory route, is typically asymptomatic.
• Establishes latent and persistent infections.
• Reactivates in immunosuppressed hosts and can cause progressive multifocal leukoencephalopathy (PML).
• Viral pathogenesis involves inoculation, multiplication in the respiratory tract, potential multiplication in kidney, possible viruria, and reactivation within the CNS.
• Primary infection is usually asymptomatic.
• Activation in immunocompromised patients, indicated by virus detection in urine, as in up to 40% of patients
• PML is a growing concern due to increasing AIDS cases.
• PML causes multiple neurological symptoms, eventually followed by paralysis, and typically results in death within 2 years.

DNA Virus: Adenovirus

• First isolated in human adenoid cell culture.
• Naked double-stranded DNA viruses.
• Spread through aerosols, close contact, or fecal-oral routes.
• Can cause lytic infections (mucoepithelial cells), latent infections (lymphoid and adenoid cells), and transforming infections (animal cells only).
• Clinical syndromes include undifferentiated upper respiratory tract infections, pharyngoconjunctival fever, acute respiratory disease, pertussis-like syndrome, pneumonia, acute hemorrhagic cystitis, epidemic keratoconjunctivitis, gastroenteritis, hepatitis and meningoencephalitis in infants and children.

DNA Virus: Herpesviruses

• Enveloped double-stranded DNA viruses.
• Three subfamilies: alphaherpesviruses (HHV1, 2, and 3), betaherpesviruses (HHV5, 6, and 7), and gammaherpesviruses (HHV4 and 8).
• Establish latent or persistent infections.
• Reactivation is more likely during immunosuppression.
• Table summarizing different Herpes virus types, target cells, sites of latency, and transmission routes.

DNA Virus: Herpes Simplex Virus 1 and 2

• Disease initiated by direct contact on infected tissue.
• Establishes latency in neurons.
• Reactivated by stress.
• HSV-1 commonly causes oral infections.
• HSV-2 typically associated with sexual infections.
• Clinical presentations include acute gingivostomatitis, herpes labialis (cold sores), ocular herpes, genital herpes, and other forms of cutaneous herpes.

DNA Virus: Varicella-Zoster Virus (HHV-3)

• Transmitted via respiratory droplets.
• Infects epithelial cells, fibroblasts, T cells, and neurons.
• Causes lifelong latent infection in neurons.
• Manifest as chickenpox (varicella) in initial infection.
• Reactivation as shingles (herpes zoster), affecting the sensory dermatomes.

DNA Virus: Epstein-Barr Virus (HHV-4)

• Initiates infection by saliva contact and spreads to B cells.
• Establishes latency in B cells.
• Clinical manifestations include infectious mononucleosis, Burkitt's lymphoma, and nasopharyngeal carcinoma in China.

DNA Virus: Cytomegalovirus (CMV)(HHV-5)

• Acquired by blood, body fluids, or vertical transmission.
• Infects epithelial and other cells.
• Establishes latency in T cells, macrophages, and other cells.
• Clinical manifestations include cytomegalic inclusion disease (congenital), usually asymptomatic perinatal or postnatal infections.
• Can cause infections in immunocompromised hosts: pneumonia, retinitis, colitis, and encephalopathy.

DNA Virus: Herpes Viruses 6 and 7

• Transmitted in saliva.
• Cause roseola in children (rash and fever).
• In immunocompromised individuals can lead to mononucleosis syndrome and HIV co-factor.

DNA Virus: Herpes Virus 8

• HHV-8 found in almost 100% of Kaposi's sarcoma cases.
• Tumor of blood vessels (Kaposi's sarcoma).

RNA Virus: Poxvirus

• Large, complex viruses.
• Linear double-stranded DNA genome with fused ends.
• Includes variola virus (smallpox), molluscum contagiosum, and other zoonotic viruses.
• Smallpox has been eradicated.

RNA Virus: Parvovirus

• Smallest DNA virus.
• Naked icosahedral capsid.
• Single-stranded (plus or minus) DNA strand.
• Transmitted via respiratory droplets.
• Infects mitotically active erythroid precursor cells in bone marrow.
• Only B19 can cause disease in humans

RNA Virus: Picornavirus

• Small RNA viruses.
• Naked icosahedral capsid.
• Includes enteroviruses (poliovirus, coxsackie A & B, echovirus, enterovirus, rhinovirus 1-100+, cardiovirus, aphthovirus, and hepatitis A virus).

RNA Virus: Coronavirus

• Are named for the solar corona-like appearance.
• Single-stranded (+) RNA.
• Spreads via respiratory droplets, but also found in sweat, urine, and feces.
• Four subfamilies: alpha, beta, gamma, and delta.
• Primarily from mammals (alpha and beta) and other animals (gamma and delta).
• Clinical syndromes include mild-moderate common colds, and severe forms like SARS (severe acute respiratory syndrome), MERS (Middle East respiratory syndrome), and COVID-19.

RNA Virus: Norovirus

• Positive (+) RNA viruses.
• Resistant to detergents, drying, and acid.
• Transmitted through fecal-oral routes in contaminated food or water.
• Causes 50% of gastrointestinal outbreaks in the USA.
• Clinical manifestations consist of diarrhea, nausea, and vomiting.

RNA Virus: Orthomyxovirus (Influenza)

• Enveloped viruses with segmented (-) RNA genomes.
• Three types: Influenza A, B, and C (only A and B cause disease in humans).
• Segmented genome facilitates new strains through mutation (drift) and reassortments (shift).
• Spanish flu pandemic (1918-1919) was highly lethal.

RNA Virus: Paramxyovirus

• Large virion particles with negative-sense single-stranded RNA genomes.
• Transmitted through respiratory droplets and initiate infection in the respiratory tract.
• Cause cell-cell fusion, resulting in multinucleated giant cells.
• Includes measles, parainfluenza, mumps, and respiratory syncytial viruses (RSV).

RNA Virus: Filovirus

• Filamentous, enveloped, single-stranded (-) RNA viruses.
• Cause hemorrhagic fever.
• Includes Ebola and Marburg viruses.
• Ebola endemic in some parts of Africa.

RNA Virus: Reovirus

• Non-enveloped viruses.
• Double-layered protein capsid and double-stranded RNA.
• Rotavirus is the main pathogen, causing diarrhea in children.

RNA Virus: Togavirus and Flavivirus

• Enveloped viruses with positive-sense single-stranded RNA genomes.
• Transmitted by arthropods (arboviruses).
• Togaviridae and Flaviviridae are significant for diseases like Chikungunya, Dengue, Yellow Fever, Japanese Encephalitis, Zika virus, and Hepatitis C.

RNA Virus: Bunyaviridae

• More than 200 viruses, enveloped viruses with segmented (-) RNA.
• Transmitted by arthropods or ticks (mosquitoes, etc.).
• Clinical manifestations include flu-like syndromes, encephalitis, and hemorrhagic fever.

RNA Virus: Arenaviridae

• Enveloped viruses with two circular, (-) RNA genome segments.
• Infections are zoonoses with a rodent reservoir.
• Includes Lymphocytic choriomeningitis (LCM) and hemorrhagic fever viruses (Lassa, Junin, Machupo).

Retrovirus

• Enveloped (+)-sense single-stranded RNA viruses.
• Replication through a DNA intermediate.
• HIV (Human Immunodeficiency Virus) is a lentivirus associated with AIDS.
• Composition: lipid envelope, glycoprotein (gp120 and gp41), nucleocapsid (protein p24), and RNA with enzymes supporting replication.
• Genetic Diversity: HIV has high genetic diversity, necessitating combination therapy.
• Clinical Manifestations: Acute (retroviral syndrome), Chronic, and Final/Crisis (severe immunosuppression).

Hepatitis Viruses

• Table summarizing Hepatitis A, B, C, D, and E virus characteristics.

Test your knowledge on various viruses, their transmission methods, associated symptoms, and prevention strategies. This quiz covers important aspects of viruses like Norovirus, adenoviruses, and polyomaviruses. Enhance your understanding of viral infections and their clinical implications.