Equine infectious anemia virus (EIAV) is a lentivirus similar to

HIV that infects horses. Clinical and experimental studies demonstrating immune

control of EIAV infection hold promise for efforts to produce an HIV vaccine. Antibody

infusions have been shown to block both wild-type and mutant virus

infection, but the mutant sometimes escapes. Using these data, we develop a mathematical

model that describes the interactions between antibodies and both wild-type and

mutant virus populations, in the context of continual virus mutation. The aim of this

work is to determine whether repeated vaccinations through antibody infusions can

reduce both the wild-type and mutant strains of the virus below one viral particle,

and if so, to examine the vaccination period and number of infusions that ensure

eradication. The antibody infusions are modelled using impulsive differential equations, a

technique that offers insight into repeated vaccination by approximating the

time-to-peak by an instantaneous change. We use impulsive theory to

determine the maximal vaccination intervals that would be required to reduce the

wild-type and mutant virus levels below one particle per horse. We show that seven

boosts of the antibody vaccine are sufficient to eradicate both the wild-type and the

mutant strains. In the case of a mutant virus infection that is given infusions of

antibodies targeting wild-type virus (i.e., simulation of a heterologous

infection), seven infusions were likewise sufficient to eradicate infection, based

upon the data set. However, if the period between infusions was sufficiently increased,

both the wild-type and mutant virus would eventually persist in the form of a

periodic orbit. These results suggest a route forward to design antibody-based vaccine

strategies to control viruses subject to mutant escape.