RNA Viruses II Flashcards
Rotavirus
- Reovirus, dsRNA, segmented, naked icosahedron
- disease causes severe gastroenteritis
- profuse watery diarrhea, dehydration, maladsorption
- affects infants and children (adults usually asymptomatic)
- > 600,000 deaths, mostly in developing world
- peak incidence in winter
Influenza Virus
- Orthomyxovirus, (-) ssRNA, segmented, enveloped
- acute respiratory illness, mainly during the winter
- “uncomplicated”
- upper and/or lower respiratory tract involvement
- fever, headache, myalgia, and weakness
- “complicated”
- primary pneumonia caused by influenza
- secondary bacterial pneumonia
- mixed viral and bacterial pneumonia
- muscle involvement: myositis (pain) and rhabdomyelitis (breakdown)
HIV
-retrovirus, + ssRNA, 2 copies (can have differences), enveloped
Rotavirus life cycle
- attach and internalization and then breaks free of early endosome
- genome is segmented, one gene each
- RDRP in the virion first transcribes mRNA
- after viral proteins are translated, new virions and genome segments are synthesized in the cytoplasm
- virions assemble and then bud into the rough ER
- Egress is via exocytosis (membrane vesicles carry virions out) or by cell lysis
- virions mature in gut lumen, then infect more enterocytes or are shed in profuse diarrhea
Rotavirus Diagnosis, Treatment, Prevention
- diagnosis: not required in most cases
- treatment: Oral rehydration solutions
- prevention: live attenuated vaccines- Rotarix and Rotateq
Influenza Life Cycle
- the Haemagglutin lets it bind to the cell and endocytosis
- it is released inside the cell, the cRNA and mRNA is made in the nucleus
- genome is segmented, (-) ssRNA
- genome segments traffic to the nucleus for transcription and replication by RDRP
- viral proteins and genome segments accumulate at the plasma membrane
- virions assemble and egress by budding
- Neuraminidase (N antigen) releases virions from sialic acid on cell surface (antiviral target)
- virions are shed in respiratory droplets (coughs and sneezes)
Flu Treatments and Prevention
- Antiviral drugs
- Tamiflu (oseltamivir), Influenza A and B
- Relenxa (zanamirivir), Influenza A and B
- Amantadine and Rimantadine, Influenza A only
Vaccines
- Fluzone- trivalent inactivated vaccine
- FluMist live attenuated vaccine
2013-2014 trivalent vaccines
- A/California/7/2009 ) H1N1
- A/Texas/50/2012 H3N2
- B/ Yamagata lineage
Influenza Reassortment and Mutation
- different subtypes of influenza A
- there is an antigenic shift (genetic shuffling)
- this causes a pandemic flue with a new influenza A subtype
- there is then antigenic drift (random mutation)
- this leads to different Influenza A strains like the seasonal flu
New HIV infections and AIDS related deaths
- the rate of new HIV infections increased until 1996 and then has been declining gradually
- the AIDS realted deaths increased until 2005, where there has been better medicinal control and acceptance to get treatment
Acute HIV Infection
- Systemic: Fever, weight loss
- Pharyngitis
- Mouth: Sores, Thrush
- Esophagus: Sores
- Muscles: Myalgia
- Liver and Spleen: Enlargement
- Central: Malaise, Headache, Neuropathy
- Lymph nodes: lymphadenopathy
- Skin: rash
- Gastric: nausea, vomiting
Stages of HIV Disease
1) Exposure to virus (transmission)
2) Primary HIV infection (acute phase)
3) Seroconversion
4) Latent period
5) Early symptomatic HIV infection
6) AIDS (CD4 cell count below 200/mm^3
7) Advanced HIV infection (CD cell count below 50/ mm^3
HIV Cell Tropism
-only humans can be infected
-virus binds to CD4 and chemokine receptors on T cells and macrophges
-depletion of these cells and chronic immune activation cause immunodeficiency
HIV-R5- co receptor is CCR5 and macrophages
HIV-R5X4- co receptor is CCR5 or CXCR4 and T cells
HIV Load and CD4 T cells
- in the course of the HIV infection the number of CD4+ cells decreases during the acute stage but then increases again in clinical latency
- eventually it starts to decrease gradually as the infection persists
- the Virus load is really high in the acute infection and then is controlled and brought down when it gradually increases during the clinical latency and then increases very quickly
Opportunistic infections with HIV/AIDS
- bacterial skin infection
- shingles
- thrush
- severe athletes foot fungal
- oral hairy leukoplakia viral
- tuberculosis bacteria
- then AIDS defining infections
Top 10 Aids defining Conditions
1-P. carinii pneumonia 2- esophageal candidiasis 3- wasting 4- Kaposi's sarcoma 5- Disseminated M. avium infection 6- Tuberculosis 7- Cytomegalovirus disease 8- HIV-associated dementia 9- Recurrent bacterial pneumonia 10- toxoplasmosis
