Viruses — MCQs

A 3-month old male infant with HIV infection is brought to the physician for evaluation. The physician recommends monthly intramuscular injections of a monoclonal antibody to protect against a particular infection. The causal pathogen for this infection is most likely transmitted by which of the following routes?

A microbiologist is involved in research on the emergence of a novel virus, X, which caused a recent epidemic in his community. After studying the structure of the virus, he proposes a hypothesis: Virus X developed from viruses A and B. He suggests that viruses A and B could co-infect a single host cell. During the growth cycles of the viruses within the cells, a new virion particle is formed, which contains the genome of virus A; however, its coat contains components of the coats of both viruses A and B. This new virus is identical to virus X, which caused the epidemic. Which of the following phenomena is reflected in the hypothesis proposed by the microbiologist?

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 immunologist is studying the stages of development of T lymphocytes in the thymus. He knows that double-negative T cells do not express CD4 or CD8 molecules. After undergoing development within the subcapsular zone in the thymus, double-negative T cells begin to move towards the medulla. While en route within the outer cortex, they upregulate CD4 and CD8 molecules and become double-positive T cells. At this stage, which of the following CD molecules is most likely to be present on the cell surface?

A 5-year-old girl presents to the emergency room with acute airway obstruction. Physical examination shows cough, episodic wheezing, and excess mucus production. Increased quantities of which of the following would predispose the child to extrinsic asthma:

A medical student is reading about a specific type of T cells that plays an important role in immunologic tolerance. Most of these cells develop in the thymus, but some of them also develop in peripheral lymphoid organs. Usually, they are CD4+ cells and also express CD25 molecules. The functions of these cells are dependent on forkhead box P3 (Foxp3). Their function is to block the activation of lymphocytes that could react with self-antigens in a potentially harmful manner. Which of the following interleukins is secreted by these cells?

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 2-year-old girl who emigrated from Pakistan 2 weeks ago is brought to the emergency department because of lower limb weakness for one-day. One week ago, she had a 3-day episode of flu-like symptoms that resolved without treatment. She has not yet received any routine childhood vaccinations. Deep tendon reflexes are 1+ in the right lower extremity and absent in the left lower extremity. Analysis of cerebrospinal fluid shows a leukocyte count of 38 cells/mm3 (68% lymphocytes), a protein concentration of 49 mg/dL, and a glucose concentration of 60 mg/dL. Which of the following is the most likely diagnosis in this patient?

A 35-year-old woman from San Francisco has been refusing to vaccinate her children due to the claims that vaccinations may cause autism in children. Her 10-year-old male child began developing a low-grade fever with a rash that started on his face; as the rash began to spread to his limbs, it slowly disappeared from his face. When the child was taken to a clinic, the physician noticed swollen lymph nodes behind the ears of the child. Which of the following are characteristics of the virus causing these symptoms?

A 25-year-old woman, gravida 2, para 1, at 24 weeks' gestation comes to the physician for a prenatal visit. She reports feeling fatigue and having swollen legs lately. One month ago, she had a low-grade fever, a runny nose, painful joints, and a sore throat that resolved spontaneously. Pregnancy and delivery of her first child were uncomplicated. She does not smoke or drink alcohol. She does not use illicit drugs. Medications include folic acid and a multivitamin. Vital signs are within normal limits. Pelvic examination shows a uterus consistent in size with a 24-week gestation. There is bilateral edema around the ankles. Pelvic ultrasonography shows fluid accumulation within the fetal scalp and signs of pleural effusions bilaterally. Which of the following is the most likely underlying cause of these findings?