Production of bovine herpesvirus type 1-seronegative latent carriers by administration of a live-attenuated vaccine in passively immunized calves.
The consequences of the vaccination of neonatal calves with the widely used live-attenuated temperature-sensitive (ts) bovine herpesvirus type 1 (BHV-1) were investigated. The ts strain established acute and latent infections in all vaccinated calves either with or without passive immunity. Four of seven calves vaccinated under passive immunity became clearly BHV-1 seronegative by different serological tests, as did uninfected control calves after the disappearance of maternal antibodies, and they remained so for long periods. A cell-mediated immune response was detected by a BHV-1 gamma interferon assay, but this test failed to detect the seronegative latent carriers (SNLCs). While they are not detected, SNLCs represent a threat for BHV-1-free herds or countries. This study demonstrates that SNLCs can be easily obtained by inoculation with a live-attenuated BHV-1 under passive immunity and that latent carrier animals without any antibody do exist. Consequently, this situation could represent a good model to experimentally produce SNLCs.
Lemaire
M
M
Department of Infectious and Parasitic Diseases, Virology, Faculty of Veterinary Medicine, University of Liège, B-4000 Liège, Belgium.
Meyer
G
G
Baranowski
E
E
Schynts
F
F
Wellemans
G
G
Kerkhofs
P
P
Thiry
E
E
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D002353:Carrier State / Q000662:veterinary* / Q000821:virology; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000517:prevention & control / Q000821:virology*; D006566:Herpesviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D007242:Herpesvirus 1, Bovine / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D007112:Immunity, Maternally-Acquired; D007116:Immunization, Passive; D007371:Interferon-gamma / Q000096:biosynthesis; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*; D017735:Virus Latency
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines; D007371:Interferon-gamma