A 27-year-old man develops malaise, fatigue, and loss of appetite three weeks after a meal at the Trucker's Cafe. He notes passing dark urine. On physical examination, he has mild scleral icterus and right upper quadrant tenderness. Laboratory studies show serum AST of 62 U/L and ALT of 58 U/L. The total bilirubin concentration is 3.9 mg/dL, and the direct bilirubin concentration is 2.8 mg/dL. His symptoms abate over the next 3 weeks. On returning to the cafe, he finds that the city's health department has closed it. Which of the following serologic test results is most likely to be positive in this patient?

He most likely developed mild, self-limited liver disease from HAV infection after a meal at a restaurant with the consumption of contaminated food or water. The presence of IgM anti-HAV indicates recent infection. The IgM antibody is replaced within a few months by IgG antibodies, which impart immunity to reinfection. The incubation period for HAV infection is short, and the illness is short and mild, with no significant tendency to develop chronic hepatitis. The most common mode of infection for HAV is via the fecal-oral route. HBV and HCV infections have longer incubation periods and are most often acquired parenterally. HDV infection develops from coinfection with HBV or by superinfection in a hepatitis B carrier.