Lymphocytic choriomeningitis virus

 A 27-year-old male veterinarian comes to his primary care provider because he has been “feeling awful”. He first developed a headache 7 days ago. He felt feverish at the time, and noticed an erythematous rash with small, raised lesions on a flat base. The symptoms cleared in 3 days. Now, his headache has returned with pain at the back of his skull that is worse with nodding his head. He also feels more fatigued. His temperature is 39.0°C (102.2°F), pulse is 60/min, respirations are 18/min, and blood pressure is 120/80 mm Hg. His throat is erythematous without any exudate, and he has slightly decreased range of motion of flexion of the neck. His physical exam is otherwise unremarkable. A lumbar puncture is performed, and the cerebrospinal fluid (CSF) is sent for analysis. Which of the following is the most likely result?