The purpose of this study is to evaluate the pharmacokinetic (PK) of a single-dose of rilematovir co-administered with a single-dose of ciclosporin compared to a single-dose administration of rilematovir alone.

Inclusion Criteria:

• Body weight not less than 50 kilograms (kg) and body mass index (BMI; weight kg/height^2 [meter {m^2}]) within the range 18.0 to 30.0 kilograms per meter square (kg/m^2) (inclusive)
• Female participants, except those that are of non-childbearing potential, must have a negative highly sensitive serum (beta-human chorionic gonadotropin [beta-hCG]) at screening and a negative urine pregnancy test on Day -1 of Treatment Period 1
• A female participant using hormonal contraceptives as a means of birth control (a stable treatment for at least 30 days prior to screening) must agree to continue use of the same hormonal contraceptives throughout the study and for 90 days after the end of last study treatment
• Blood pressure (after the participant is supine for at least 5 minutes) between 90 and 140 millimeter of mercury (mmHg) systolic, inclusive, and no higher than 90 mmHg diastolic
• A 12-lead electrocardiogram (ECG) consistent with normal cardiac conduction and function, including: normal sinus rhythm (heart rate between 45 and 90 beats per minute, extremes included); QTc interval less than or equal to (<=) 450 milliseconds (ms) for men, <= 470 for women; QRS interval of less than (<) 110 ms; PR interval <= 200 ms; electrocardiogram morphology consistent with healthy cardiac conduction and function

Exclusion Criteria:

• Participants with abnormal values for alanine aminotransferase (ALT) and aspartate aminotransferase (AST) Grade 1 or greater (greater than [>] 1.25* upper limit of normal [ULN])
• Participants with any history of clinically significant skin disease such as, but not limited to, dermatitis, eczema, drug rash, psoriasis, food allergy, and urticaria
• Known allergies, hypersensitivity, or intolerance to rilematovir or its excipients. Known allergies, hypersensitivity, or intolerance to ciclosporin or its excipients
• Participant has received an experimental drug, vaccine or used an experimental medical device within 1 month or within a period less than 10 times the drug's half-life, whichever is longer, before the first dose of the study intervention is scheduled
• Participant has a history of human immunodeficiency virus (HIV) antibody positive, or tests positive for HIV at screening

The data sharing policy of the Janssen Pharmaceutical Companies of Johnson & Johnson is available at www.janssen.com/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu