Rechallenge With a Low Pathogenicity Avian H10N7 Influenza Virus in Healthy Human Volunteers Previously Challenged With H10N7 Influenza

Background: Influenza (flu) is a virus that can infect humans and animals. In humans, the flu can cause mild symptoms such as fever, cough, sore throat, runny nose, muscle aches, headaches, and fatigue. It can also cause sinus infections or pneumonia. Some flu strains, such as H5N1 and H7N9, which come from birds, can lead to more severe symptoms or death. Others, like H10N7, also come from birds but usually cause mild symptoms. Researchers want to study bird flu in humans to help develop new flu vaccines and treatments. Objective: To learn more about how bird flu viruses infect humans. Eligibility: Healthy people aged 18 to 55 years who were infected with the H10N7 bird flu strain as part of a previous study. Design: Participants who were infected with H10N7 in a previous study will be infected again with the same virus. The virus will be sprayed into their nostrils. Participants will stay in the hospital for at least 9 days. They will stay in an isolation unit. No outside visitors will be allowed. During their stay, participants will provide blood, urine, and nasal fluid samples. They will have tests of their heart and lung function. They will complete questionnaires about their symptoms. Participants will remain in the hospital until they test negative for the flu 2 days in a row. They will continue to complete questionnaires about their symptoms for 2 weeks after they were infected with the virus. Participants will have 2 follow-up visits, at 5 weeks and 9 weeks after they were infected. They will have a physical exam and provide samples of blood and nasal fluids. They will have a test of their heart function. ...

* INCLUSION CRITERIA: An individual must meet all of the following criteria to be eligible for study participation: 1. Previously participated in the H10N7 influenza challenge study 20-I-0160 ("Dose- Escalation Study of a Low Pathogenicity Avian H10N7 Influenza Virus in a Healthy Human Challenge Model") and given a viral challenge H10N7. 2. \>=18 and \=1 year) or history of hysterectomy. 2. Agrees to practice abstinence. 3. Agrees that, with heterosexual intercourse with a fertile male partner, she will use an acceptable form of contraception, and her male partner will use a condom with spermicide. Acceptable effective methods of female contraception include the following: bilateral tubal ligation, implant of levonorgestrel, injectable progestogen, intrauterine device, oral contraceptive pills, and diaphragm with spermicide. 8. Willing to have samples stored for future research. 9. Human immunodeficiency virus (HIV) uninfected with a negative test within 90 days of inoculation (Day 0). 10. Ability to speak English. EXCLUSION CRITERIA: An individual meeting any of the following criteria will be excluded from study participation: 1. Has self-reported or medically documented significant medical condition including but not limited to: 1. Chronic pulmonary disease (e.g., asthma, emphysema). 2. Chronic cardiovascular disease (e.g., cardiomyopathy, congestive heart failure, cardiac surgery, ischemic heart disease, known anatomic defects). 3. Chronic medical conditions requiring close medical follow-up or hospitalization during the past 5 years (e.g., insulin-dependent diabetes mellitus, renal dysfunction, hemoglobinopathies). 4. Immunosuppression or ongoing malignancy. 5. Neurological and neurodevelopmental conditions (e.g., cerebral palsy, epilepsy, stroke, seizures). 6. Post-infectious or post-vaccine neurological sequelae. 2. Has close or household (i.e., share the same apartment or house) high-risk contacts including but not limited to: 1. Persons \>=65 years of age. 2. Children \