Viral diagnostics — MCQs

A 23-year-old woman presents with vulvar ulcers and lymphadenopathy. Testing confirms primary HSV infection. Which of the following statements about HSV antibody development is correct?

If the genetic material were isolated and injected into the cytoplasm of a human cell, which of the following would produce viable, infectious virions?

A rapid diagnostic test has been developed amid a major avian influenza outbreak in Asia. The outbreak has reached epidemic levels with a very high attack rate. Epidemiologists are hoping to use the rapid diagnostic test to identify all exposed individuals and curb the rapid spread of disease by isolating patients with any evidence of exposure to the virus. The epidemiologists compared rapid diagnostic test results to seropositivity of viral antigen via PCR in 200 patients. The findings are represented in the following table: Test result PCR-confirmed avian influenza No avian influenza Positive rapid diagnostic test 95 2 Negative rapid diagnostic test 5 98 Which of the following characteristics of the rapid diagnostic test would be most useful for curbing the spread of the virus via containment?

The occupational health department at a hospital implements new safety precautions to prevent laboratory-acquired infections. One of the new precautions includes disinfecting the microbiology laboratory benches with 70% ethanol before and after use. This measure is most likely to be effective in preventing the transmission of which of the following viruses?

A 41-year-old woman comes to the primary care physician’s office with a 7-day history of headaches, sore throat, diarrhea, fatigue, and low-grade fevers. The patient denies any significant past medical history, recent travel, or recent sick contacts. On review of systems, the patient endorses performing sex acts in exchange for money and recreational drugs over the last several months. You suspect primary HIV infection, but the patient refuses further evaluation. At a follow-up appointment 1 week later, she reports that she had been previously tested for HIV, and it was negative. Physical examination does not reveal any external abnormalities of her genitalia. Her heart and lung sounds are normal on auscultation. Her vital signs show a blood pressure of 123/82 mm Hg, heart rate of 82/min, and a respiratory rate of 16/min. Of the following options, which is the next best step in patient management?

A 45-year-old man visits the office with complaints of severe pain with urination for 5 days. In addition, he reports having burning discomfort and itchiness at the tip of his penis. He is also concerned regarding a yellow-colored urethral discharge that started a week ago. Before his symptoms began, he states that he had sexual intercourse with multiple partners at different parties organized by the hotel he was staying at. Physical examination shows edema and erythema concentrated around the urethral meatus accompanied by a mucopurulent discharge. Which of the following diagnostic tools will best aid in the identification of the causative agent for his symptoms?

Nucleic acid amplification testing (NAAT) of first-void urine confirms infection with Chlamydia trachomatis. Treatment with the appropriate pharmacotherapy is started. Which of the following health maintenance recommendations is most appropriate at this time?

A 17-year-old male comes to the physician because of painful genital sores, malaise, and fever for 3 days. He is sexually active with 3 female partners and does not use condoms consistently. His temperature is 38.3°C (101°F). Physical examination shows tender lymphadenopathy in the left inguinal region and multiple, punched-out ulcers over the penile shaft and glans. Microscopic examination of a smear from the ulcer is most likely to show which of the following?

An investigator is processing a blood sample from a human subject. A reagent is added to the sample and the solution is heated to break the hydrogen bonds between complementary base pairs. This solution is then cooled to allow artificial DNA primers in the solution to attach to the separated strands of the sample DNA molecules. An enzyme derived from the thermophilic bacterium Thermus aquaticus is added and the solution is reheated. These steps are repeated multiple times until the aim of the test is achieved. The investigator most likely used which of the following laboratory procedures on the test sample?

A virology student is asked to identify a sample of virus. When subjected to a nonionic detergent, which disrupts lipid membranes, the virus was shown to lose infectivity. The student then purified the genetic material from the virus and subjected it to treatment with RNase, an enzyme that cleaves the phosphodiester linkages in the RNA backbone. A minute amount of the sample was then injected into a human cell line and was found to produce viral particles a few days later. Which of the following viruses was in the unknown sample?