The present invention relates, first, to the discovery, identification, and characterization of novel 
nucleic acid molecules, that are associated with PBC, Sjögren'
s syndrome, scleroderma, SLE, autoimmune 
thyroiditis and various other 
connective tissue disorders. The novel 
nucleotide sequences of the present invention are retroviral in origin and are indicative of a PBC 
retrovirus which bears a strong correlation with PBC. The present invention is based, in part, on the Applicant's data which is the first evidence to suggest that PBC patient's tissue may harbor a transmissible agent. The association of a retroviral 
infectious agent with PBC was first demonstrated by Applicants 
in vitro by co-culture of periportal 
lymph nodes derived from patients at time of 
transplantation and healthy biliary 
epithelium cells. The Applicant's discoveries as described herein, report the characterization of PBC-associated 
infectious agent as retroviral as demonstrated by 
electron microscopy and immunoblot reactivity. In addition, Applicants have characterized novel 
nucleotide sequences which are associated with the PBC-associated 
retrovirus.