Replication of the bovine immunodeficiency-like virus in diploid and aneuploid cells: permanent, latent and virus-productive infections in vitro.

Bovine immunodeficiency-like virus (BIV) is an infectious and leukotropic retrovirus, the sole lentivirus candidate which has been isolated from cattle. Although BIV has recently been shown to be related to the human immunodeficiency virus, there is very limited information on the replication and the pathogenesis of BIV. It is reported here that BIV can permanently infect diploid and aneuploid cells from four different species: bovine, canine, ferret and ovine. With the exceptions of a bovine diploid and a canine aneuploid cell line, all lines were virus non-productive. However, BIV was rescued by co-cultivation of virus non-productive cells with homologous BIV-free or canine cells (Cf2Th). A permanent and BIV-productive infection was established for 90-serial subcultures in a canine cell line. A BIV titre of 1 x 10(6)/0.1 ml was observed in stationary culture and 1 x 10(10)/0.1 ml in suspension culture. The canine cell line above was used for production of BIV antigens, whereas BIV-free canine cells were routinely used to isolate BIV from BIV non-productive cells infected in vitro and from blood from experimentally BIV-infected cattle. The different steps of virus maturation were similar by electron microscopy to those of lentiviruses. BIV results are compared to those of lentiviruses.