This diagram illustrates the potential outcomes following a cat's exposure to the Feline Leukemia Virus (FeLV), detailing the different infection pathways and the presence of antibodies.

FeLV Exposure: The process begins with a cat being exposed to FeLV through shared bowls, grooming, bites, or other close contact with an infected cat.

Week 1:

• Abortive Infection (~25%): Approximately 25% of cats are able to mount an effective immune response early on, leading to an abortive infection. In this scenario, the cat's immune system clears the virus before it can establish a persistent infection. Antibodies against FeLV are produced and can be detected, but the virus itself is not present in the bloodstream or tissues. These cats will test negative for FeLV in antigen and PCR assays but will have developed antibodies to the virus.
• Focal/Atypical Infection (<5%): Less than 5% of cats develop a focal or atypical infection, where the virus may be present in specific tissues (like the mammary glands or bladder) but not in the blood or bone marrow. The presence of antibodies can be inconsistent in this type of infection, and the infection may be difficult to detect using standard tests.

Week 3:

• Regressive Infection (~35%): In about 35% of cases, the cat's immune system suppresses the virus, resulting in a regressive infection. Antibodies are present, and viral replication is minimal or absent. This type of infection may persist for life, with the possibility of reactivation under immunosuppression, such as during pregnancy or due to certain medications.
• Progressive Infection (~35%): In another 35% of cases, the infection progresses, with the virus spreading and establishing a persistent presence in the cat's body. This leads to a progressive infection characterized by persistent viremia. Despite the presence of antibodies, the immune system fails to control the virus, resulting in severe clinical outcomes, including lymphoma, leukemia, fibrosarcomas, various anemia (immune-mediated hemolytic anemia, aplastic anemia, pure red cell aplasia), reproductive issues, neurological disorders, gastrointestinal disease and other (e.g., osteochondromatosis, cutaneous horns).