During a subtraction study on gene expression in human kidney mesangial cells 
(HMCs), cDNA clones with sequence homology to paramyxovirus P, M and F genes 
were isolated. Subsequent investigation revealed that this particular HMC line 
was infected with a previously unknown paramyxovirus. Here, we report the 
isolation and genome characterization of this new virus, now named Beilong virus 
(BeV). The genome of BeV is 19,212 nucleotides (nt) in length and is the largest 
among all known members of the order Mononegavirales. The BeV genome contains 
eight genes in the order 3'-N-P/V/C-M-F-SH-TM-G-L-5'. The SH and TM genes code 
for a small hydrophobic protein of 76 aa and a transmembrane protein of 254 aa, 
respectively. The BeV G gene, at 4527 nt, codes for an attachment protein of 734 
aa and contains two additional open reading frames (ORFs) in the 3' half of the 
gene, coding for putative proteins of 299 and 394 aa in length. Although the 
exact origin of BeV is presently unknown, we provide evidence indicating that 
BeV was present in a rat mesangial cell line used in the same laboratory prior 
to the acquisition of the HMC line, suggesting a potential rodent origin for 
BeV.