IMMUNIZA TION OF CATS AGAINST MICROSPORUM CANIS

RybnikH A., V. Vrzal, 1. Chumela, 1. Petras: Imml/nization of Cats Against Microsporum canis. Acta vet. Bmo 1997, 66: 177-181. MICANFIN, a commercial vaccine against Microsporum canis, manufactured by BIOVETA, pic., Ivanovice na Ham\ was tested in a challenge bio-assay on cats. The immunized cats showed satisfactory protection against experimental infection with M. canis. Non-vaccinated controls given the same challenge dose developed dermatophytosis. Microsporum canis. vaccine, protective efficacy Skin mycotic diseases in cats have been given considerable attention for a number of years. One reason of this is, no doubt, the fact that cats are major sources of dermatophytosis in humans and particularly in children (B a x t e r 1973, And ria s jan 1978, Po g I aye n and Tam pie r i 1985, L un d e rand L un d e r 1992). In long-term studies Microsporum canis has been found to play the main role in the aetiology of feline skin mycosis, being incriminated in 90 % to 100 o/c of the cases examined (P e c h e u rand G e r in 1978, Kristensen and Krogh 1981, Sparkes et al. 1993, Larsson et al. 1994). What makes the control of the disease particularly difficult is the fact that not only evidently diseased cats, but also clinically healthy animals harbouring M. canis in their haircoat may bethesourceofinfection(Moriello and DeBoer 1991,Gambale etal.I993). For the therapy of feline dermatophytosis a number of preparations have been suggested (M 0 r i e II

Skin mycotic diseases in cats have been given considerable attention for a number of years.One reason of this is, no doubt, the fact that cats are major sources of dermatophytosis in humans and particularly in children (B a x t e r 1973, And ria s jan 1978, Po g I aye n and Tam pie r i 1985, L un d e rand L un d e r 1992).In long-term studies Microsporum canis has been found to play the main role in the aetiology of feline skin mycosis, being incriminated in 90 % to 100 o/c of the cases examined (P e c h e u rand G e r in 1978, Kristensen and Krogh 1981, Sparkes et al. 1993, Larsson et al. 1994).What makes the control of the disease particularly difficult is the fact that not only evidently diseased cats, but also clinically healthy animals harbouring M. canis in their haircoat may bethesourceofinfection (Moriello and DeBoer 1991,Gambale etal.I993).
For the therapy of feline dermatophytosis a number of preparations have been suggested (M 0 r i e II 0 1990, M 0 ri e II 0 and DeB 0 e r 1995), The experience with the local and oral therapy has not been invariably favourable (D e B 0 e rand M 0 r i e 11 0 1995), To have a satisfactory effect, these preparations must be administered daily for a long period of time.Chemotherapeutic methods have not conferred a sufficient degree of immunity, which makes reinfection possible.
All the afore-mentioned facts and successful practical experience with immunoprophylaxis and immunotherapy of trichophytosis in farm animals (S ark is 0 v and Kolesnikov 1989, Rybnikar et al. 1996b) have prompted the development of vaccines against feline dermatophytosis.Our results of testing a newly developed vaccine against M. canis for its protective efficacy are reported in the present report . .

\Iaterials and Methods
The experimental animals were clinically healthy 3-to 8-month old domestic cats.males and females. in a good nutritional state.The vaccine used for immunization of the cats was MICANFIN, manufactured by BIOVET A, pic .. Ivanovice na Hane, Czech Republic.This liquid vaccine contains inactivated Jlicrosporum canis culture and aluminium hydroxide as adjuvant.Nine cats were each injected subcutaneously twice with I ml of the vaccine in the region behind the shoulder blade.Four cats were each injected intramuscularly twice with I ml of the vaccine into the hind leg muscle.The interval between vaccination and revaccination was I ~ days.The revaccination was carried out on the side opposite to that used for primary vaccination.
Five weeks after revaccination the immunized cats and 8 non-vaccinated controls of the same age were challenged with a virulent Microsporum canis strain.The suspension of challenge culture was inoculated into a 4 x 6 cm clipped and gently scaritied area of the right tlank at the rate of I to I.S x 10' eFU per animal.The animals were then observed for clinical skin changes at the challenge site and elsewhere for 28 days after challenge.At the end of the experiment skin lesion and haircoat specimens were collected from the challenge site from all the cats for examination by culture and for microscopic examination (R Y b n i k a i' 1992).

Results
In 2 cats vaccinated by the subcutaneous route and in 1 cat vaccinated intramuscularly a mild swelling was observed at the site of injection; this disappeared spontaneously within one week.The remaining animals showed no undesirable post-vaccination reaction.
Skin mycotic changes after challenge Days after challenge 15 17 21 The results of the protective efficacy of MICANFIN are presented in Table 1.It can be seen that the vaccinated cats responded to challenge by the development of minute superficial squamous changes which disappeared, for the most part, by day 21 (Plate XV., Fig. 1).In 2 cats vaccinated subcutaneously they persisted up to post-challenge day 21 and 25, respectively.At the end of the experiment all the vaccinated cats were clinically negative, showing growth of new healthy haircoat.
The non-vaccinated controls challenged with the same inoculation dose as the vaccinated animals showed either solitary or confluent mycotic foci (Fig. 2).In half of them these changes persisted till the end of the experiment.In the remaining controls they were also perceptible up to post-challenge day 28, but showed a gradual subsidence.The results of both examination by culture and microscopic examination were in keeping with the clinical findings.They were negative in the vaccinated cats and demonstrated M. canis in 7 out of the 8 controls.

Discussion
The results of testing experimental vaccines against Microsporum canis have been reported by several writers.Having failed in treating a M. canis-affected kitten with griseofulvine, M 0 she r et a\.( 1977) used an inactivated vaccine prepared by themselves.They administered it intramuscularly once a week for a period of 5 weeks with a good therapeutic effect.The animal became clinically negative afterthe 5th vaccination.
E I a d and S ega 1 (1989) developed an experimental vaccine prepared from M. canis ribosomal fraction and tested it on guinea-pigs by injection into the paws followed by intradermal inoculation 14 days later.In this way the humoral an cellular components of the immune system were stimulated and the vaccinated guinea-pigs became immune against experimental infection with M. callis ( E I a d and S ega I 1994).
Inactivated vaccine was reported to induce active immunity against M. canis in guineapigs (P i e r et a\.1995).After being exposed to challenge, none of the vaccinated animals developed clinical disease, whereas 70 % of non-vaccinated controls showed clinical signs of dermatophytosis.
Similar results with their own inactivated vaccine against M. canis were reported by Wawrzkiewicz and Ziolkowska (1996).The vaccinated guinea-pigs did not develop disease when challenged with a M. canis dose as high as 10 5 CFU.
In our previous study (R Y b n i k a i' et a\.1996a) we tested the efficacy of a living vaccine against M. canis in dogs and calves.Its protective efficacy was good.Nevertheless, in 3 out of 5 vaccinated dogs squamous changes reminiscent of mycotic foci were observed at the inoculation site.
All the afore-mentioned experimental vaccines showed good immunogenic potency but, to our knowledge, none of them has been introduced into veterinary practice.More or less the same also applies to a vaccine prepared at the University of Wisconsin (D e B 0 e rand M or i e II 0 1995; M ori e II 0 and DeB 0 e r 1995).The vaccine was administered to cats intradermally every other week for a period of 10 weeks.The vaccinated cats showed the same rise in their blood serum antibody titre as did the infected cats but the level of their cellular immunity was lower as against the infected animals.Protective efficacy of the vaccine against challenge and natural infection with M. canis was not recorded.
In 1994 Fort Dodge Laboratories introduced Fel-O-Vax MC-K vaccine into veterinary practice (M 0 r i e II a and DeB 0 e r 1995).The vaccine contains an inactivated M. canis strain and adjuvant.It is administered subcutaneously three times in 1 ml doses.The intervals between the vaccinations are 12 to 16 and 26 to 30 days.The safety and potency tests of the vaccine were canied out by M 0 r i e II 0 and DeB 0 e r (1995).They observed a few undesirable post-vaccination reactions, namely the development of mild swelling and hair loss at the site of inoculation and post-vaccination lethargy.Therapeutic vaccination of infected cats produced an improvement of the clinical state in some but not in all the animals.
In our experiment with MICANFIN vaccine we observed slight undesirable postvaccination reaction in 2 out of 9 cats vaccinated subcutaneously and in lout of 4 cats after intramuscular administration.They consisted in mild swelling which disappeared spontaneously within a week.No further post-vaccination reactions were observed.In challenge bio-assay on cats MICANFIN showed satisfactory protective efficacy.Good protection against experimental infection with M. canis was recorded after both subcutaneous and intramuscular administration.
In the Czech Republic MICANFIN vaccine was introduced into veterinary practice in 1996.Up to now about 1 300 cats have been vaccinated.The results evaluated so far by veterinarians and cat fanciers have been positive.The advantage ofMICANFIN, compared with the afore-mentioned preparations, is that both prophylactic and therapeutic effect is achieved after its two administrations.
The results of testing MICANFIN in dogs is the subject of another report.

Table I
Test of the protective efficacy of MICANFIN vaccine