Nature, Structure & Classification of viruses COPY Flashcards
What are positive-sense single-stranded RNA (+ssRNA) viruses? Give an example.
Viruses with RNA that can act as mRNA and be directly translated into proteins. Example: Poliovirus (Picornaviridae).
What are negative-sense single-stranded RNA (-ssRNA) viruses? Give an example.
Viruses that require transcription into a complementary positive strand before translation. Example: Influenza virus (Orthomyxoviridae).
What are double-stranded RNA (dsRNA) viruses? Give an example.
Viruses with a genome consisting of double-stranded RNA. Example: Rotavirus (Reoviridae).
What are retroviruses? Give an example.
RNA viruses that use reverse transcription to integrate into the host genome. Example: HIV (Retroviridae).
What are ambisense RNA viruses? Give an example.
Viruses with segments containing both positive and negative-sense RNA sequences. Example: Lassa virus (Arenaviridae).
List five causes of viral gastroenteritis.
- Astroviruses
- Calciviruses
- Noroviruses
- Coronaviruses
- Adenoviruses 40/41
- Rotaviruses
Name three viruses transmitted via direct contact.
- Monkeypox
- Herpes Simplex Virus (HSV)
- Human Papillomavirus (HPV)
Name three viruses transmitted via airborne droplets.
- Influenza virus
- SARS-CoV-2
- Measles virus
Name three viruses transmitted via the fecal-oral route.
- Hepatitis A
- Norovirus
- Rotavirus
Name three viruses transmitted via vector-borne transmission.
- Dengue virus (mosquitoes)
- Lassa fever virus (rats)
- Crimean-Congo hemorrhagic fever virus (ticks)
What is antigenic drift?
Gradual accumulation of small mutations in viral genes, leading to partial immune evasion. Example: Seasonal influenza changes.
What is antigenic shift?
Abrupt genetic reassortment between viruses, leading to new strains and possible pandemics. Example: 2009 H1N1 pandemic.
What is the function of the bacteriophage capsid?
Protects the viral genome and aids in delivery into the host cell.
What is the function of bacteriophage tail fibers?
Recognizes and binds to specific receptors on the bacterial host cell.
List five measures to prevent rabies transmission.
- Vaccinate domestic animals
- Human pre-exposure prophylaxis
- Post-exposure prophylaxis (PEP)
- Avoid contact with wild animals
- Public awareness campaigns
Name five factors that lead to the reactivation of HHV-3 (Varicella-Zoster Virus).
- Weakened immune system
- Stress
- Chronic illness
- Immunosuppressive medications
- Exposure to Varicella-Zoster Virus
List five strategies used to control influenza epidemics.
- Surveillance
- Vaccination
- Antiviral drugs
- Isolation of infected persons
- Limiting travel
What is an endemic viral disease? Give an example.
A disease consistently present in a population. Example: Dengue in tropical regions.
What is an epidemic viral disease? Give an example.
A sudden outbreak of a disease in a specific area. Example: Ebola in West Africa (2014-2016).
What is a pandemic viral disease? Give an example.
A global spread of a new disease. Example: COVID-19 (SARS-CoV-2).
List five measures to prevent Hepatitis A infection.
- Vaccination
- Safe drinking water
- Proper sewage disposal
- Hand hygiene
- Food safety regulations
Name four viral families with segmented genomes.
- Orthomyxoviridae (Influenza)
- Reoviridae (Rotavirus)
- Arenaviridae (Lassa virus)
- Bunyaviridae (Hantavirus)
List five symptoms of congenital rubella syndrome.
- Sensorineural hearing loss
- Cataracts
- Congenital heart defects
- Microcephaly
- Hepatosplenomegaly
Name five viruses associated with CNS infections and their transmission routes.
- Polio (fecal-oral)
- Rabies (animal bites)
- Mumps (close contact)
- West Nile (mosquitoes)
- HSV-2 (sexual intercourse)
List five ways viruses evade the immune system.
- Antigenic drift
- Antigenic shift
- MHC class I downregulation
- Latency
- Interferon inhibition
What are the key steps in the HIV replication cycle?
- Attachment
- Entry
- Uncoating
- Reverse transcription
- Integration
- Transcription
- Translation
- Assembly
- Budding
- Maturation
Name an HIV drug that targets each stage of the viral cycle.
- Attachment: Maraviroc (CCR5 antagonist)
- Fusion: Enfuvirtide (fusion inhibitor)
- Reverse Transcription: Zidovudine (NRTI), Efavirenz (NNRTI)
- Integration: Raltegravir (integrase inhibitor)
- Maturation: Lopinavir (protease inhibitor)
List five viruses and the cancers they cause.
- Epstein-Barr Virus (EBV): Burkitt’s lymphoma, Nasopharyngeal carcinoma
- Human Herpesvirus 8 (HHV-8): Kaposi’s sarcoma
- Hepatitis B & C Viruses: Hepatocellular carcinoma
- Human Papillomavirus (HPV): Cervical, anal, and oropharyngeal cancers
- HTLV-1: Adult T-cell leukemia
List one symptom of adenovirus infection for each system.
- Respiratory: Pneumonia
- Gastrointestinal: Gastroenteritis
- Eyes: Conjunctivitis
- Renal: Hemorrhagic cystitis
- CNS: Meningoencephalitis
Name five complications of mumps.
- Encephalitis
- Deafness
- Orchitis
- Pancreatitis
- Myocarditis
List five characteristics of HPV.
- DNA virus
- Infects epithelial cells
- Over 200 types
- Sexually transmitted
- Associated with warts and cancers
Name antiviral drugs used for influenza and Hepatitis C.
- Influenza: Oseltamivir (Tamiflu), Zanamivir, Amantadine
- Hepatitis C: Sofosbuvir, Ribavirin, Interferon
