Answers To Virology Mcq Paper 2

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Answers to virology MCQ Paper 2 http://virology-online.com/questions/MCQPaper2answers.ht Answers to Multiple Choice Questions - Paper 2 Instructions for candidates The examination consists consists of 30 multiple choice questions, each divided into 5 different parts. Eac h part c ontains a statement which could be true or false. Eac h question will have at least one pa rt which is true. For each part, you should indicate whether you think it is true (T), false (F), or don’t know (DN). You must fill in in the relevant square with a black pen. One mark will be given for each correct answer and one mark  deducted for e ach incorrect answer. You will not be marked for those questions for which you have indicated "don’t know". 1. Viruses may contain True DNA True RNA True Glycoprotein True Enzymes False Cell wall Comments Comments Viruses Viruses may may contain either DNA, DNA, or RNA. RNA. They may may contain enzymes such as polymerases, polymerases, and have glycoproteins glycoproteins in their envelope 2. Viruses are True Obligate in intracellular pa parasites False May divide by binary fission False Have their own metabolism True May contain enzymes for replication True May have an envelope Comments Comments Unlike Unlike bacteria, viruses viruses do not have their own metabolism metabolism and do do not divide divide by binary fission. fission. They They are intracellular intracellular parasites and may c ontain enzymes for their replication. Some viruses possess possess a lipid envelope. 3. The following statements are true Fals alse All virus ruses are are sen senssitive tive to anti antivi vira rall agen agents ts True Virus Virus infected cells may be transformed. True Viruses may have a lipid envelope enve lope True Viruses Viruses may produce cytopathic changes in cell culture True Some Some viruses are destroyed by lipid lipid solvents Comments Comments To date, only only a few viruses viruses can be treated by antiviral agents. Some Some viruses viruses such as oncornaviruses can transform transform cells. cells. Some Some may have a lipid lipid envelope which may be destroyed by lipid solvents. solvents. 4. The following are direct dete ction methods True Detection of rotavirus antigen in faecal specimens False Single radia l haemolysis (SRH) False CMV DEAFF test True Electron microscopy microscopy True P olymerase chain reaction Comments Comments SRH SRH is a serological serological assay, and the CMV DEAFF test is a rapid rapid culture test. The The rest are used to detect virus particles, antigens, antigens, and nucleic acid directly from a specimen 5. The following methods may be used for serological diagnosis 1 f7 01/01/2011 15 18 Answers to virology MCQ Paper 2 http://virology-online.com/questions/MCQPaper2answers.ht True Complement-fixa tion tests (CFT) False Polymerase chain reaction (PCR) True Single Single Radial Haemolysis (SRH) False CMV DEAFF test True Western blot Comments PCR detects viral genomes directly. The The CMV DEAFF test is a rapid culture culture assay. Western Western blot is is mainly mainly used as a serological serological test 6. A serological diagnosis of a primary viral infection may be made False Detection of viral-specific viral-specific IgA False Detection of viral-specific viral-specific IgD False Detection of viral-specific viral-specific IgE True Detection of viral-specific viral-specific IgM True Seroconversion Comments Comments A diagnosi diagnosiss of a primary primary viral infection infection may be made by the detection of IgM IgM and/or seroconv seroconversi ersion. on. 7. The following are e xamples of viral genome detection (molecular methods) methods) True Southern blot False Western blot False RIBA (Recombinant (Reco mbinant immunoblot assay) True Branched DNA True Polymerase chain reaction (PCR) Comments Comments Southern blot, blot, branched DNA, DNA, and PCR are viral genom genomee detection methods. methods. Western Western blot and RIBA RIBA are serologi serological cal assays assays 8. The following statements are true False For cytomegalovirus cytomegalovirus (CMV), (CMV), the cytopathic (CPE) effect usually usually appears within 24-48 hours True For some viruses, the CPE is so characteristic that so further identification is required. True Paramyxovirus causes syncytia formation in cell culture False A given given virus always produce identical CPE in different cell cultures True Immmunofluroescence Immmunofluroescence may be used to identify a virus in cell culture Comments Comments It takes 1-3 weeks for CMV-specific CMV-specific CPE CPE to appear. For some some viruses such as herpes simplex, simplex, the CPE is so characteristic that so further identification identification is required. 9. Poliovirus can be typed by 2 f7 False Single Single radial haemolysis (SRH) False Haemagglutination Haemagglutinat ion inhibition test (HAI) False DEAFF test True Neutralization Neutralization test True Hybridization Hybridization with specific nucleic acid probes Comments Comments Polioviruses Polioviruses can be typed by by neutralization neutralization tests and hybridization hybridization with specific nucleic acid probes. SRH SRH and HAI are not used. The DEAFF test is used for the isolation of CMV 01/01/2011 15 18 Answers to virology MCQ Paper 2 http://virology-online.com/questions/MCQPaper2answers.ht 10. Immunofluorescence Immunofluorescence techniques can be used to detect the following directly from the speci men. True Chlamydia True CMV True Respiratory Respirato ry Syncytial Virus (RSV) True Influenza virus True Rabies virus Comm omments ents All the the abo above ve 11. The following statements are true for the haemagglutination-inhibition haemagglutination-inhibition (HAI) test. False Not a quantitative test True Treatment of patient serum is necessary to remove non-specific non-specific inhibitors inhibitors True Animal blood is nece ssary True Usually more specific than complement fixation tests (CFT) True May be used for the diagnosis diagnosis of rubella infection Comments Comments HAI is is a quantitative test. It is is widely widely used in in rubella rubella serology. serology. It is usually more specific specific than CFT. CFT. Treatment of patient patient serum is necessary to remove non-specific inhibitors. inhibitors. 12. Regarding cell culture False Viruses can only be culture d using cell lines False The presence of cytopathic effect is the only way to detect a virus True The neutralization test is the mainstay mainstay of identification of a poliovirus poliovirus isolate isolate False The haemagglutination haemagglutinat ion inhibition test is the mainstay of identifica tion of a respiratory respirat ory syncytial syncytia l virus (RSV) isolate False Whole blood is the specimen of choice for many common viruses Comments Comments Viruses Viruses may may also be cultured cultured in eggs eggs and animals. animals. The The presence of virus may be detected by CPE as well as haemadsoption, haemadsoption, and presence of viral particles and antigen. 13. A standard Polymerase Chain Reaction (PCR) consists of  False Denaturation, annealing, annealing, and ligation ligation steps True Denaturation, annealing, and extension steps True dNTPs True Mg++ ions True Taq polymerase Comments Comments Denaturation Denaturation,, annealing, annealing, and ligati ligation on steps occur in LCR. LCR. PCR consists consists of Denaturation, Denaturation, annealing annealing,, and extension steps. steps. It requires dNTP, Mg++, ta q polymerase, a nd t arget-specific arget-specific oligonucleotide oligonucleotide primers. 14. Modification of a standard PCR include f7 True Nested PCR False branched DNA (bDNA) True RT-PCR (Reverse transcription PCR) 01/01/2011 15 18 Answers to virology MCQ Paper 2 http://virology-online.com/questions/MCQPaper2answers.ht True Quantitative PCR False 3SR (Isothermal (Isother mal amplification) Comments Comments Nested Nested PCR, RT-PCR RT-PCR and quantitative quantitative PCR are modifi modification cationss of the PCR protocol. protocol. bDNA and 3SR 3SR are alternative alternative amplification amplification techniques. 15. Safety measures for preventing PCR contamination include True The use of uracil-N-glycosylase urac il-N-glycosylase (UNG) True Use Use of filtered pipette tips True Separate areas for master mix, template, and PCR product operation True Dedicated pipettes for master mix, template, and PCR products True Ultraviolet irradiation Comments Comments All All the above above may be useful useful in in preventing preventing contaminati contamination on of PCR. PCR. 16. The following statements are usually true True PCR is more sensitive sensitive than branched DNA assays Fal False Bran Branch ched ed DNA is more ore sen sensi siti tive ve than than Lig Ligase ase cha chaiin reac reacti tion on True Exponential amplification amplification occurs in PCR True Linear amplification amplification occurs in branched DNA True PCR is extremely liable liable to contamination Comments Comments Exponential amplifi amplification cation occurs in in PCR, LCR LCR and NASBA NASBA/3SR. /3SR. Therefore these techniques are extremely liable liable to contamination and are more sensitive than branche d DNA, where linear amplification amplification occurs. 17. Laboratory diagnosis of infectious mononucleosis mononucleosis include True Detection Dete ction of VCA-IgM False Detection of VCA-IgA False Seroconversion against EBNA True Paul-Bunell test True VCA IgG avidity test Comments Diagnosis Diagnosis of infectious mononucleosis mononucleosis is usually usually made by the Pa ul-Bunell ul-Bunell where hete rophil antibodies are detect ed and by the detection of EBV-IgM. EBV-IgM. VCA-Ig VCA-IgG G avidity test may be used t o confirm equivocal cases. Detec tion of elevate d titres of VCA-IgA VCA-IgA correlates with an increased risk for nasopharyngeal carcinoma and is used as a screening test. Seroconversion against against EBNA does not t ake place until months after the initial initial illness. illness. 18. Viruses that routinely establish latent infections in human sensory ganglia include f7 False Epstein-Barr virus True Herpes Simplex Virus type 1 True Varicella-Zoster Virus True Herpes Simplex Virus type 2 False Human herpesvirus 6 Comments Comments All the above herpesviruses can cause latent infections. However, However, only HSV HSV 1+2, and VZV VZV routinely establish establish latent latent infections in human sensory ganglia. 01/01/2011 15 18 Answers to virology MCQ Paper 2 http://virology-online.com/questions/MCQPaper2answers.ht 19. Rapid diagnosis of CMV disease i nclude True CMV pp65 antigenaemia False Conventional cell culture True DEAFF test True Detection Dete ction of CMV-DNA in blood by PCR False Rising antibody titres Comments Rapid diagnosi diagnosiss of CMV disease include include CMV CMV pp65 antigenaemia, antigenaemia, DEAFF DEAFF test, and Detection of CMV-DN CMV-DNA A in blood by PCR. 20. The following viruses viruses are associated with respiratory infections False Rotaviruses True Adenoviruses True Influenza viruses False HTLV-1 True RSV Comments Comments Rotaviruses cause diarrhoea. HTLV-1 HTLV-1 is associated with with adult T-cell T-cell leukaemia leukaemia and tropical tropical spastic spastic paraparesis. 21. The following viruses viruses are thought to cause gastroenteritis False Ente roviruses True Ade noviruses True Norwalk-like viruses True Astroviruses True Rotaviruses Comments Comments Although Although enteroviruses may be found found in faeces, they are not associated associated with gastroenteritis. gastroenteritis. The other viruses viruses are associated associated with gastroenteritis. 22. The following viruses are transmitted from animals to humans True Influenza A H5N1 False HTLV-1 True Hantaviruses False P oliomyelitis True Rabies Comments Influenza A H5N1 is is otherwise otherwise known as the "bird "bird flu" It It afflicted Hong Kong in late late 1997 and was transmitted transmitted from poultry poultry to humans. Hantaviruses is transmitted transmitted from rodents to humans and rabies can be transmitted from various mammals to humans. 23. A chronic carrier state may occur in the following: 5 f7 False Hepatitis A True Hepatitis B True Hepatitis C True Hepatitis Delta False Hepatitis E Comments Comments A chronic chronic carrier carrier state can exist exist in hepatitis hepatitis B, B, C and Delta Viru Viruss infection infectionss 01/01/2011 15 18 Answers to virology MCQ Paper 2 http://virology-online.com/questions/MCQPaper2answers.ht 24. The following viruses are tr ansmitted by blood False Rubella True HIV False Measles True HBV True HCV Comments Comments HIV, HIV, HBV and HCV are transmitted transmitted by blood. Rubella and measles are transmitted transmitted via respiratory respiratory droplets 25. The following may be useful for prognostic purposes in HIV-infected individuals False HIV envelope antibody True HIV-p24 antigen True CD4 count False CD8 count True HIV viral load Comments Comments HIV envelope antibody remains remains high high throughout the course course of HIV infections and thus does not carry any prognostic prognostic value. HIV-p24 HIV-p24 antigen had been widely used in the past as a prognostic prognostic marker but it has been superseded by HIV viral load. CD4 count plays an important role in telling us what stage the disease is at. 26. The following markers are usually present in a hepatitis B carrier with chronic active hepatitis True HbsAg False HbsAb False Anti-HBc IgM True HBV-DNA True HbeAg Comments Comments In patients with with chronic active hepatitis, hepatitis, HBV replication is is present and hence HBV-DNA HBV-DNA and HbeAg. HbsAg HbsAg is present. present. Anti-HbcIgM Anti-HbcIgM is normally normally absent although it may occasionally be dete cted during periods of exac erbations. 27. Regarding viral infection of the central nervous system (CNS) True rue Meni eningi ngitis tis may occur ccur tog togethe etherr with ence enceph phal aliitis tis True True Enter Enterov ovir irus uses es are are one one of the the com commo mones nestt caus causes es of CNS CNS infect nfectio ions ns in child childho hood od False Electron Elect ron microscopy of the cerebrospinal cere brospinal fluid (CSF) is a useful diagnostic test Fals alse PCR PCR has has no role ole in in the the diagn agnosi osis of CNS infec nfecti tion onss True rue The dete detect ctiion of anti antibo body dy in the the CSF CSF is is a use usefu full diag diagno nost stiic mar marke kerr Comments Comments Meningitis Meningitis usually occurs together with with encephalitis. Enteroviruses Enteroviruses are one of the commonest causes of CNS infections in childhood. Electron microscopy is too insensitive insensitive to be useful as a diagnostic diagnostic test. P CR assays for HSV are now routinely used for the diagnosis of herpes simplex encephalitis. The detection of antibody in the CSF is a useful diagnostic marker 28. Regarding rash illnesses 6 f7 True Varicella-zoster Varicella-zoste r virus (VZV) (VZV) infection infect ion may cause a vesicular rash Fals Falsee The The ras rash h caus caused ed by parv parvov oviirus rus B19 B19 is is due due to the the pre prese sence nce of viru viruss in the skin skin 01/01/2011 15 18 Answers to virology MCQ Paper 2 http://virology-online.com/questions/MCQPaper2answers.ht Fals alse Meas easles is usual ually diag diagno nossed by viral cul cultur ture True Herpes simplex virus (HSV) (HSV) infection infect ion is usually diagnosed by viral culture False VZV cannot cann ot be grown in cell culture Comments Comments Varicella-zoster Varicella-zoster virus (VZ (VZV) V) infection may may cause a vesicular rash. rash. The rash rash caused by parvovirus parvovirus B19 is is probably an allergic allergic reaction due to the deposition of immune complexes. Measles is usually diagnosed by serology. Herpes simplex virus (HSV) infection is usually diagnosed by viral culture. VZV can be grown in cell culture although this is rarely used for diagnosis. 29. Rubella infection True Can be asymptomatic True May be indistinguishable from parvovirus parvov irus B19 False Can have serious side effects when occurring in a woman in the third trimester of pregnancy True Is usually usually preventable by vaccination True May be acquired by having close contact with an infant with congenital rubella syndrome Comments Comments Rubella infection infection can be asymptomatic. asymptomatic. It may be indistin indistinguis guishable hable clinically clinically from parvovirus B19 B19 infection. The most most serious effects occur when a pregnant woman is infected in the first trimester trimester of pregnancy. It is usually usually preventable by vaccination. Infants with congenital rubella rubella syndrome pose a great infectious risk since they may excre te virus in great quantities up to 1 year of age. 30. Regarding laboratory tests for rubella 7 f7 True Rubella immunity immunity may be determined by an enzyme immunoassay immunoassay Fal False CFT CFT is com commonl only used used for for the the di diagno agnossis of acut acutee inf infec ecti tion on True IgM antibody is usually detectable after the onset of rash False Rubella vi virus ca cannot be be cu cultured Fal False PrePre-na nata tall dia diag gnos nosis of of rub rubel ellla in in a foe foetu tuss is is si simple ple and and rel reliiabl able Comments Comments Rubella immuni immunity ty may be determined by an enzyme enzyme immunoassay. immunoassay. CFT is not commonly commonly used for the diagnosi diagnosiss of rubella rubella infection; Haemagglutination-i Haemagglutination-inhibiti nhibition on tests a re. IgM antibody is usually detectable a fter the onset of rash Rubella virus can be cultured although this is rarely used as a method of diagnosis. diagnosis. Pre-nat al diagnosis diagnosis of rubella in a foetus such as amniocentesis involve some some degree of risk to the fetus. 01/01/2011 15 18