However, both seropositive and seronegative patients have been seen to respond to the same treatments. Most patients are seronegative for NMO-IgG and GFAP, biomarkers for neuromyelitis optica. One study shows some acute-phase seronegative Lyme patients have antibodies bound up in these complexes. Individuals are at a 10-fold less risk of MS if they are seronegative for EBV. It is not known if seronegative myasthenia gravis will respond to standard therapies. However, individuals with intracranial lesions and calcifications may be seronegative. Many white Americans become sexually active while seronegative for HSV-1. Vaccination is recommended also for seronegative sows and boars. Many of these men were HIV-negative (seronegative). Crohn's disease is associated with a type of rheumatologic disease known as seronegative spondyloarthropathy. These are called Highly Exposed Persistently Seronegative (HEPS). It is classified as a type of seronegative spondyloarthropathy. Enthesopathy is also sometimes present in association with seronegative .