Effects of a single dose of an intranasal feline herpesvirus 1, calicivirus, and panleukopenia vaccine on clinical signs and virus shedding after challenge with virulent feline herpesvirus 1

Abstract

The objective of this study was to determine whether intranasal administration of a commercially available FVRCP vaccine to kittens lessened clinical signs and feline herpesvirus 1 (FHV-1) viral shedding when compared to unvaccinated control kittens after FHV-1 challenge. Three groups of 10 unvaccinated kittens were administered one dose of vaccine 6 days (group 1), 4 days (group 2), or 2 days (group 3) before challenge, respectively. One group was maintained as unvaccinated controls (group 4). FHV-1 challenge was then induced and the kittens were observed for 14 days. When the grouped vaccinated kitten results (groups 1-3) were compared to group 4 results, clinical scores following challenge were significantly lower (P<0.05) and significantly lower body temperatures (P<0.05) were detected on days 0, 5 and 9 post-challenge. When evaluated by individual group, group 1 and group 2 kittens had significantly lower clinical scores (P<0.05) than group 4 kittens post-challenge. In addition, FHV-1 shedding was lower in group 1 kittens when compared to group 4 kittens on day 6 after challenge (P<0.05). Administration of this vaccine within several days prior to exposure lessened clinical signs of disease and FHV-1 shedding compared to unvaccinated kittens.

Epidemiological status of felid herpesvirus type-1 and feline calicivirus infections in Brazil

“…Live and inactivated vaccines for the parenteral administration against FCV and FeHV-1 and (in some countries) live intranasal vaccines against FeHV-1 are marketed (ORR et al, 1980;LAPPIN et al, 2006). However, vaccines do not provide full protection and clinical disease and viral shedding still may occur (LAPPIN et al, 2006); therefore, massive vaccination should be performed, aiming to reduce the incidence of the disease.…”

Feline calicivirus

“…However, because the virus replicates at the site of inoculation, clinical signs such as mild sneezing may be seen after several days in some individuals [55,74]. Where available, intranasal vaccines are particularly useful when a rapid onset of protection is required e.g.…”

“…In contrast to parenteral vaccines, only a single dose of intranasal vaccine is generally required to induce immunity following primary vaccination. Most published studies have used a feline herpesvirus challenge where high levels of protection have been shown four days after intranasal vaccination and partial protection after two [55,74]. These vaccines may also overcome MDA better than parenteral vaccines, although in general their use is only licensed in kittens from 12 weeks of age.…”

Feline herpesvirus

“…All types of vaccine induce reasonable protection against disease in previously unexposed cats. However, none of the vaccines appears to protect against infection or the development of the carrier state, although both viral shedding and latency load of wild-type virus after viral challenge may be reduced in vaccinated cats compared to unvaccinated controls [28,70,99,100,130,147]. Although intranasal vaccine virus can become latent [147], the situation with parenterally vaccinated cats is still unclear [130].…”

“…Intranasal MLV vaccine induces better protection but often induces some mild side effects, such as transient sneezing and occasionally other clinical signs [70,100]. Intranasal vaccines, however, are useful for rapid onset of protection, with partial protection seen after 2 days and significant protection after 4 and 6 days [10,11,70].…”