Effects of bovine lactoferrin on in vitro replication of feline herpesvirus.
OBJECTIVE
To investigate the effects of bovine lactoferrin on in vitro replication of feline herpes virus (FHV-1) and to determine at what points during viral replication these effects occur.


METHODS
Cultured Crandell-Reese feline kidney (CRFK) cells and FHV-1 strain 727.


METHODS
Five concentrations of bovine lactoferrin (0.5, 1, 2, 5, and 10 mg/mL) were added at one or more of three time points during conventional plaque reduction assays: (a) uninfected CRFK cells were incubated in lactoferrin-containing medium for 30 min prior to viral adsorption; (b) virus was suspended in lactoferrin-containing medium prior to and during adsorption, or (c) CRFK cells were incubated with lactoferrin-containing medium for 48 h following viral adsorption. Plaques were counted and antiviral effect expressed as percent inhibition relative to control medium that contained no lactoferrin.


RESULTS
Exposure of CRFK cells to lactoferrin prior to or during viral adsorption inhibited FHV-1 replication by 87-96% (mean: 91%). Application of lactoferrin following viral adsorption had no appreciable effect on FHV-1 replication. No additive or synergistic effects were noted when lactoferrin was added at multiple steps. These effects were similar at all concentrations of lactoferrin tested. Cytotoxic effects of lactoferrin on CRFK cells were not observed at any concentration tested.


CONCLUSIONS
Bovine lactoferrin has a notable inhibitory effect on the in vitro replication of FHV-1 prior to and during, but not following viral adsorption. These findings strongly suggest that lactoferrin inhibits FHV-1 adsorption to the cell surface and/or penetration of the virus into the cell. Clinical effects of topical lactoferrin in acute or recrudescent herpetic episodes in cats warrant investigation.
Beaumont
Stephanie L
SL
Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Maggs
David J
DJ
Clarke
Heather E
HE
D000818:Animals; D002415:Cats; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D007781:Lactoferrin / Q000008:administration & dosage / Q000494:pharmacology*; D018140:Varicellovirus / Q000187:drug effects* / Q000502:physiology; D014779:Virus Replication / Q000187:drug effects*
D007781:Lactoferrin