Monitoring of Antibodies Titre Against Canine Distemper Virus in Ferrets Vaccinated with a Live Modifi ed Vaccine

Pavlačík L., V. Celer Jr., V. Kajerová, V. Jekl, Z. Knotek, I. Literák: Monitoring of Antibodies Titre Against Canine Distemper Virus in Ferrets Vaccinated with a Live Modifi ed Vaccine. Acta Vet. Brno 2007, 76: 423-429. A group of fi ve ferrets vaccinated against the canine distemper virus (CDV) was evaluated as to the onset of anti-CDV antibody production and the serum levels of the animals were monitored for one year. The ferrets were immunized with a live attenuated vaccine. The vaccination pattern was as follows: primary vaccination at the age of 6 weeks, fi rst revaccination at 30 days after primary vaccination, and second revaccination after another 30 days. Blood samples were taken prior to primary vaccination and then at 30-day intervals (sampling 1 to 12). The whole experimental cycle covered the period of one year from primary vaccination (till the age of 1 year and 6 weeks). Serum samples were analysed for anti-CDV virus-neutralisation antibodies using a virusneutralisation test using the Onderstepoort CDV strain. All ferrets had zero virus-neutralisation antibody titres before primary vaccination. Two ferrets produced virus-neutralisation antibodies as a response to fi rst revaccination. A stable antibody level (titre 256) was maintained between months 4 and 11 after primary vaccination and a sudden increase in antibody titre (titres 512 and 1024 2048) occurred in both animals in months 11 and 12. The reason for the abrupt rise in antibody titres in the two animals remains unclear. No anti-CDV seroconversion was observed in the three remaining animals. Regarding the results obtained in this study we do not consider commonly recommended vaccination with a live attenuated anti-CDV vaccine as an effective method of antibodies induction against distemper in young ferrets. Small mammals, Mustelidae, immunoprophylaxis, Morbillivirus Caused by the RNA virus from the Paramyxoviridae family (Kelleher 2001; Rosenthal 2004), canine distemper is one of the most serious diseases found in ferrets. No specifi c therapy is available to treat this infection and the mortality is around 100% (McDonald and Lariviere 2001; Antinoff 2004). Approaches to vaccination of ferrets against canine distemper caused by the CDV differ worldwide. A monovalent vaccine for ferrets called Fervac D (Fervac-D, United Vaccines, Madison, WI) has been available in the US for several years (Fox 1998; Schoemaker 2002; Quesenberry and Orcutt 2004), polyvalent dog vaccines based on modifi ed live virus are still used in Europe (Lewington 2003), e.g. a vaccine from the Nobivac and Decalvac DHPPiL line (Intervet, NE) is used in Great Britain and some other European countries. The canine distemper strain contained in these vaccines is derived from the Onderstepoort strain cultivated on VERO cell lines. Vaccine Galaxy-D (Solvay Animal Health) can be employed, too, but it is not originally intended for ferrets and its effi cacy against canine ACTA VET. BRNO 2007, 76: 423-429; doi:10.2754/avb200776030423 Address for correspondence: MVDr. Lukáš Pavlačík, Ph.D. Štefánikova 1029 544 01 Dvůr Králové nad Labem Czech Republic E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm distemper in ferrets has not been confi rmed with confi dence yet (Langlois 2005). Only polyvalent vaccines have been available in Australia and New Zealand so far and there is certain consensus between veterinary practitioners and companies that polyvalent vaccines for dogs may be used in ferrets there, too (Lewington 2003). The basic prerequisite is that the vaccines are prepared using tissue cultures other than from ferrets, i.e. for example monkey tissue cultures or cultures from chicken embryos. Inactivated canine distemper virus vaccines cannot be recommended due to reported unreliable effi cacy (Newcomer 1998). Svoboda (1998) recommends vaccination with modifi ed live virus passaged in chicken cells. Fox (1998) presents the possibility of using a modifi ed live vaccine prepared on tissue cultures from chicken embryos (CETCO). The author does not regard inactivated vaccines as reliable and does not recommend their use in ferrets. He also reports very good results achieved in ferrets with vaccines intended for dogs (e.g. Nobivac D, Nobivac DH2, Trimune) or Vanguard DA2PL (Pfi zer Animal Health, Belgium). One relatively often discussed issue is the potential agreement between the canine distemper strain used for vaccine preparation and the presence of a corresponding fi eld strain in the given region (Fox 1998; Lewington 2003). The fi rst vaccination in ferrets is carried out at 6 to 8 weeks of age. The reported half-life of the maternal antibodies is 9.4 days (Appel and Harris 1988). Vaccination before week 6 is not advisable due to possible interactions of vaccine antigens with maternal antibodies (Langlois 2005). The next vaccination is administered at week 10 to 12 and then at week 13 to 14 of age. Young ferrets should be kept in isolation for another two weeks after vaccination. The animals are then kept immune by annual revaccination. Vaccination of ferrets against CDV in the Czech Republic is performed with polyvalent vaccines for dogs based on live CDV modifi ed on VERO cells, suited to both ferrets and dogs as far as safety is concerned. Post-vaccination antibody control, however, has not been paid due attention as yet. The goal of this study was to assess the onset of antibody production and monitor antibody blood levels at regular intervals in a group of ferrets vaccinated with a vaccine of a type commonly used against CDV in both dogs and ferrets in the Czech Republic. Materials and Methods Animals used in the experimental study The study used 5 domestic ferrets (Mustela putorius furo) from 6 weeks of age. The animals were three females and two males, not related to one another. The ferrets were kept in two separate groups males and females in cages with fi ve solid walls. All animals were kept in a single room at the same hygienic conditions. The animals were implanted microchips in the dorsal region between the shoulder blades. They were referred to by codes F plus numbers 1 to 5 in the log. Ferrets F2, F4 and F5 were females and ferrets F1 and F3 were males. The ferrets were fed commercial granulated food ad libitum and had permanent access to drinking water. Vaccination The ferrets were immunized against CDV with commonly used commercial vaccines Biocan® Puppy D + Biocan® Puppy P and Biocan® DHP + Biocan® L (Bioveta, a.s., Ivanovice na Hané, Czech Republic). Biocan® Puppy D is a live attenuated anti-CDV vaccine; Biocan® Puppy P contains attenuated, lyophilised canine parvovirus and Biocan® DHP contains inactivated CDV, infectious hepatitis and infectious laryngotracheitis virus. Biocan® L is an inactivated vaccine against leptospirosis containing Leptospira canicola and L. grippotyphosa. The vaccination pattern was as follows: primary vaccination at 6 weeks of age with vaccine Biocan® Puppy D + Biocan® Puppy P, fi rst revaccination at 30 days after primary vaccination with vaccine Biocan® DH + Biocan® L, and second revaccination with vaccine Biocan® DH + Biocan® L after another 30 days. The ferrets received triple anti-CDV immunization. The vaccines were given subcutaneously in the region between the shoulder blades.