RA-1 Virus
A new member in the family?


A small particle, named rheumatoid associated parvovirus-like agent (RA-1 virus), resembles parvoviruses in physicochemical and morphological properties.  It was derived from the synovial tissue of a patient with severe rheumatoid arthritis. The etiology of rheumatoid arthritis, a disease thought to be associated with infectious agents ranging from bacteria to viroids, has evaded investigators for years -- could RA-1 be involved in causing this debilitating condition?  Is RA-1 a true member of the parvovirus family?  Some investigations have been conducted, but these questions remain unresolved.


Recent studies have identified RA-1 as a DNA parvovirus.  In one study, investigators were able to isolate 24-nm particles in the brains of mice that had been inoculated with extracts of synovial cells.  A single stranded DNA fragment, approximately 4.5 kilobases in size, was extracted from the particles.  The apparent small size of the isolate, the particles' resistance, and the particle pathogenesis in neonatal rodents also suggests that it is a parvovirus.  However, studies of the molecular properties of this DNA species with restriction enzymes show that it has a cleavage pattern that differs from existing parvoviruses. It has not been established that RA-1 is related to existing parvoviruses of mammalian species.


In a study conducted with neonatal mice, the RA-1 virus elicited a syndrome in the animals that included neurological disturbances, alopecia (sporadic loss of body hair), blepharitis, dwarfism, "masking," permanent crippling of the limbs and a rigid curvature of the thoracic spine.


The RA-1 virus remains an attractive candidate for the induction of rheumatoid arthritis in humans, as well as a candidate for membership in the parvovirus family.  Polyclonal antibodies detect the presence of RA-1 in patients with rheumatoid arthritis, but not in persons with osteoarthrits, which also supports the possible link between RA-1 and chronic rheumatoid arthritis in humans.  The exact nature of RA-1, its relationship to existing parvoviruses, and its role in causing rheumatoid arthritis are all questions that remain to be resolved in future studies.

See references #12 and #13

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