A Phase1 Study of VIB9600

Key Inclusion Criteria: 1. Healthy male and female subjects aged 18 through 65 years at the time of consent. 2. Body mass index (BMI) of 19.0 through 35.0 kg/m2 at screening and minimum weight of 50 kg. 3. Females must have been surgically sterilized. 4. Nonsterilized male subjects who are sexually active with a female partner of childbearing potential must use a male condom with spermicide from Day 1 through to the final follow-up visit. 5. Able and willing to comply with the requirements of the protocol. Key Exclusion Criteria: 1. Concurrent enrollment in another clinical study involving an investigational treatment. 2. Received administration of an investigational drug or participated in a device trial within 3 months prior to screening (Visit 1). 3. Subject is a participating investigator, sub-investigator, study coordinator, or employee of the participating site, or is a first-degree relative of the aforementioned. 4. History, or a reason to believe that a subject has a history, of drug or alcohol abuse within the 2 years prior to screening. 5. Positive test for drugs of abuse. 6. Donation of blood or blood products in excess of 500 mL within 3 months prior to screening. Not agreeing to refrain from blood or blood product donations during study participation. 7. Receiving any of the prohibited concomitant medications: 1. Any immunotherapy or immunosuppressive therapy 2. Chronic use of steroid medications 3. Immunoglobulin or blood products 4. Live vaccines 5. Anticoagulants 6. Aspirin