Virology Flashcards

Question

Paramyxoviruses

Answer 1

may produce syncytia in tissue: RSV, Parainfluenza, measles

Answer 2

Negri bodies: intracytoplasmic eosinophilic inclusion bodies

Answer 3

Used for diagnosis, prognosis, and immune status monitoring. Antigen is bad: – Implies viral activity, associated with:  Active disease (HBsAg)  Poor prognosis (HBeAg).  Positive antibody result is associated with resolved disease (HBsAb) or better prognosis (HBeAb).  Markers of acute infection are core IgM (HBcAb-IgM) and surface antigen (HBsAg): – Antigen produced before immunity – IgM, like always, is the first antibody subtype made.  Core antibody (HBcAb) is the test for exposure to HBV: – Screening marker for blood – Almost invariably present in infected patients past the acute phase – Doesn’t reflect disease activity.  Positive surface antibody (HBsAb) alone means immunization: – The HBV vaccine contains surface antigen but no core antigen. Immunized people will be HBsAb positive but HBcAb negative.

Answer 4

Mostly blood-borne – sexual transmission rare. – perinatal transmission risk is <25% of infected persons – Fulminant HCV hepatitis is very rare except in Japan.  Chronic hepatitis C – 50-85% of persons infected with HCV develop persistent, viremic infections – Asymptomatic or only mildly symptomatic – Persists for decades, with fluctuating ALT / AST levels.  Associations – Cryoglobulinemia – Kidney disease (membranoproliferative glomerulonephritis) – Other autoimmune diseases – Lymphomas and hepatocellular carcinoma

Answer 5

Hepatitis C antibody - Anti-HCV Becomes positive 6-8 weeks after infection. Marker of HCV infection Hepatitis C recombinant immunoblot - HCV RIBA Used to confirm borderline HCV antibody test Hepatitis C RNA - HCV RNA, HCV viral load, etc. Viral load (amount of virus in blood) by quantitative PCR is used to decide on and monitor therapy. For diagnosis, these are supplemental tests Hepatitis C Genotype - Provides information on viral strains used for prognostic purposes and to guide treatment decisions. Strain types 2 and 3 are more likely to respond to treatment than strain type 1

Answer 6

``` - HIV Screening EIA 1st gen: crude viral lysate 2nd gen: recombinant antigens 3rd gen: improved IgM detection 4th gen: antibody and antigen detection ``` -HIV Confirmatory Tests Western blot IFA - HIV DNA PCR For neonatal diagnosis - HIV RNA PCR for primary screening of blood products for diagnosis for viral load testing - HIV genotyping drug resistance monitoring by DNA sequencing; RT and PR mutations

Answer 7

Positive is: – CDC/ASTPHLD criteria; any two of the following bands: p24, gp41, and gp120/160

Answer 8

 Culture – Newer shell vial methods 24-48h – ‘Gold standard’  DFA – Rapid (1-2h) – Sensitivity from top centers approaches culture. – Requires fluorescent scope and highly trained technical staff.  Molecular Diagnostics – Real-time methods can be ~1h or so. – In some cases real-time PCR methods exceed culture in sensitivity (probably due to viral loss in transport) – High skill and equipment requirements – Emerging ‘gold standard’ – overall probably better than culture  Rapid antigen tests – 50-70% sensitivity, despite publications to the contrary  Lower in adults – Rapid, simple, no equipment needed.

Answer 9

```  Positive Test – Do not start antibacterials – Start antivirals – Droplet precautions – Don’t do other tests  Consequences of error: potentially severe  Specificity is essential! ``` ```  Negative Test – Consider antibacterial therapy – Do not start antivirals – No droplet precautions – Further diagnostic studies  Consequences of error: moderate  Insensitivity can be tolerated ```

Answer 10

 Two major considerations for influenza testing: –When to test? When do you start / stop testing for flu? –What specimens to collect?  How do you train your clinical staff in specimen collection?

Answer 11

When?  Remember – false-positives have potentially severe consequences, e.g. non-treatment of a serious bacterial infection.  Test during the flu season, only.  Potential strategies: – Seasonal: test Oct-Dec→March or so.  Early season – retain specimen for confirmatory testing! – Incidence-based testing – monitor regional influenza per CDC and State systems, begin testing only when influenza reported in the area.

Answer 12

Specimen collection is the critical step in influenza testing Washes are somewhat better than swabs*  Important to get ciliated epithelial cells  Children shed more virus than adults; tests tend to be more sensitive in kids.

Answer 13

```  Upper / Colds – Rhinovirus – Respiratory syncytial virus – Adenovirus – Parainfluenza – Influenza A,B – Enterovirus – EBV ``` ```  Lower / Pneumonia – Influenza A, B – Adenovirus – Respiratory syncytial virus – Human metapneumovirus – Parainfluenza – Rhinovirus – Cytomegalovirus – Varicella-zoster – Herpes simplex – Hantavirus* – SARS CoV* ```

Answer 14

```  Rotavirus  Norovirus  Adenovirus  Enterovirus  CMV (compromised patients; colitis) ```

Answer 15

```  Meningitis – Enterovirus – Herpes simplex virus – Varicella-zoster – EBV – Mumps – WNV – Jamestown Canyon – Lymphocytic choriomeningitis virus (LCMV) ``` ```  Encephalitis – Herpes simplex virus – Cytomegalovirus – Varicella-zoster – EBV – Arbovirus (EEE, WEE, SLE,West Nile, POW, etc) – Adenovirus – Measles, Rubella, Mumps – Influenza – Enterovirus – HIV – BKV – HHV-6 – Rabies – LCMV (transplant) ```

Answer 16

```  Vesicular – HSV, VZV, Enterovirus, Vaccinia, CMV, Adenovirus  Papillomas – HPV, molluscum contagiosum  Exanthems – Measles. Rubella, Enterovirus, Parvovirus B19, HHV-6, Dengue, West Nile, EBV, Adenovirus, CMV ```

Answer 17

```  Hepatitis A, B, C, D, E  HSV, especially in newborns  EBV  CMV  Adenovirus ```

Answer 18

 Mononucleosis – EBV, CMV, Adenovirus, HIV, HHV-6  Ocular – Enterovirus, Adenovirus, HSV, VZV, CMV, Vaccinia, Measles  Marrow Suppression – EBV, MV, HHV-6, Hepatitis A, B, C, Parvovirus B19, Influenza, Adenovirus, HIV