EFFICACY OF INTRANASAL FVRCP VACCINE

Cathy Ann Just, DVM
Feline panleukopenia virus (FPV), feline calicivirus (FCV), and feline herpesvirus 1 (FHV-1) are prevalent in cat populations and can cause significant morbidity and mortality in animals lacking proper immunity. Cats at greatest risk are those in multi-cat environments such as shelters, humane societies, and pet stores where the risk of exposure, stress, and potential for co-infection are high. A 2006 study by Lappin, et al. showed a single dose of a modified-live FPV, FCV, FHV-1 (FVRCP) vaccine for intranasal (IN) administration in kittens produced significantly less severe clinical signs of FHV-1 upon challenge with virulent FHV-1¹. To date, there is no similar data for FPV or FCV. This paper summarizes a recent study identifying detectable antibodies in seronegative adult cats after administration of one dose of a commercially available modified-live (MLV) FVRCP vaccine administered IN or a commercially available MLV FVRCP administered subcutaneously (SQ).

Ten, 10-month-old, mixed-sex, specific pathogen-free (SPF) cats were selected and randomly divided into two groups. All cats were unvaccinated and determined to be negative for antibodies to FPV by hemagglutination (HI) and FCV and FHV-1 by serum neutralization (SN). On Day 0, one group was vaccinated with a single dose of a MLV IN FVRCP vaccine (Feline UltraNasal^® FVRCP, Heska Corporation, Loveland, CO) and the other group was administered a commercially available MLV parenteral (SQ) vaccine (Purevax^® Feline 3, Merial LTD, Athens, Georgia). Serum samples were collected on days 0, 3, 7, 10, 14, 17, 21, 24, and 28 and evaluated by FPV HI, FCV-SN, and FHV-SN assays. Cats developing FPV titers >20 and FCV and FHV-1 titers >8 were considered positive.

By Day 10, all cats (from both groups) had titers that predict resistance to challenge and there was no statistically significant difference between seroconversion rates between the groups. These results suggest either vaccine could be used to successfully prevent clinical signs of FPV infection in previously naïve cats. In addition, a previous study (Lappin, et al. 2007)² found that Feline UltraNasal^® FVRCP vaccine generated superior antibody responses compared to two formulations of inactivated FVRCP vaccine for SQ administration.

The IN-administered FVRCP vaccine induced seroconversion to FCV more quickly than the FVRCP administered SQ. All IN-vaccinated cats had seroconverted by Day 14 compared to only one parenterally-vaccinated cat. Although all SQ-vaccinated cats eventually seroconverted, it took the full 28 days to occur. These results suggest that FVRCP-administered IN should be considered for all populations of cats at high risk for exposure to FCV.

Only two cats from the IN-administered group and none of the cats from the SQ Group seroconverted for FHV-1, suggesting more than one dose of FHV-1 is required in naïve cats. Statistically, greater lymphocyte blastogenesis has been shown (Lappin, et al., 2005)³ in cats following exposure to FHV-1 antigens via IN FVRCP vaccination compared to SQ-administered FVRCP. In that study, four different parenterally-administered FVRCP vaccines were used including the one used here.

In summary, Heska´s Feline UltraNasal^® FVRCP Vaccine, administered intranasally, has proven to stimulate more rapid seroconversion to FCV, to induce greater lymphocyte blastogenesis when exposed to FHV-1 antigens, and to induce antibody responses to FPV in naïve cats as well as parentally-administered FVRCP vaccines.






Sources:
¹ Lappin MR, Sebring RW, Porter M, Radecki SJ, Veir J (2006) “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.” Journal of Feline Medicine and Surgery 8, 158-163.

² Lappin MR, Jensen WA (2007) “Panleukopenia antibody responses following a single inoculation with one of five FVRCP vaccines.” Proceedings of the American College of Veterinary Internal Medicine 25th Annual Forum.

³ Lappin MR, Veir J, Sebring R, Radecki SV (2005) “Feline lymphocyte blastogenesis in response to feline herpesvirus 1 antigens and concanavalin A after vaccination with five FVRCP vaccines.” Proceedings of the American College of Veterinary Internal Medicine 23rd Annual Forum.