VETERINARSKI ARHIV 68 (3), 81-84, 1998

ISSN 0372-5480
Printed in Croatia

Seroconversion and duration of immunity in camels vaccinated with tissue culture inactivated rabies vaccine

Akundi P. Kalanidhi¹, Umesh K. Bissa²,
and Villuppanoor A. Srinivasan¹*

¹Indian Immunologicals, Gachibowli, Hyderabad, India

²National Research Centre on Camels, Bikaner, Rajasthan, India

* Contact address:
Dr. Villuppanoor Alwar Srinivasan,
Indian Immunologicals, Hyderabad-500 019, Road No. 44, Jubilee Hills, India,
Phone: 91 40 244 585, Fax: 91 40 244 007

KALANIDHI, A. P., U. K. BISSA, V. A. SRINIVASAN: Seroconversion and duration of immunity in camels vaccinated with tissue culture inactivated rabies vaccine. Vet. arhiv 68, 81-84, 1998.

ABSTRACT

A study was conducted in camels (Camelus dromedarius) vaccinated with a single dose, or two doses, of inactivated tissue culture rabies vaccine. The seroconversion pattern and duration of immunity were then monitored for 48 months. The study indicated a good serological response when measured in terms of the Rapid Fluorescent Focus Inhibition Test (RFFIT). Titres ranging from 2.13±1.2 IU to 6.07±2.03 IU at one month post-vaccination period, and serum antibody levels above 0.5 IU were maintained for 48 months post-vaccination period in both groups of animals. This study indicated that inactivated tissue culture rabies vaccine induced a satisfactory immune response in camels when tested for a period of 48 months.

Key words: camel, Camelus dromedarius, seroconversion, prophylaxis, Raksharab, India

Introduction

The rearing of camels is quite common in parts of north-west India, especially in States such as Rajasthan, The Punjab, Haryana and Gujarat. The camel population in India is approximately 1.2 million. These animals are used extensively for draft and transportation purposes. As with most other domestic animals, camels may become victims of bites from rabid dogs, which cause fatal consequences with the subsequent development of rabies. BLOCK and DIALLO (1995) reported that rabies was a possible cause of death of camels in Niger.

Rabies is the one of the viral diseases that can be effectively controlled by vaccination with inactivated tissue culture vaccines. Recently, RAMANNA et al. (1991) and RAMANNA and SRINIVASAN (1992) reported the use of inactivated tissue culture rabies vaccine for prophylaxis in dogs and bovines in India. The present paper deals with a study conducted on camels to discover the seroconversion pattern and duration of immunity with an adjuvanted inactivated tissue culture rabies vaccine produced with a Challenge Virus Standard (CVS) strain using Baby Hamster Kidney (BHK 21) cell culture.

Vaccine

The commercially available vaccine "Raksharab" (Indian Immunologicals, Hyderabad, India) was used in the trial. The vaccine is an inactivated adjuvanted rabies vaccine produced with a CVS strain grown in BHK suspension cell cultures. (RAMANNA et al., 1991).

Animals

Twenty camels (Camelus dromedarius) reared in the Camel Breeding Farm of the National Camel Centre for Camels, Bikaner (India) were selected for the trial. The animals were randomly allotted to two groups, ten animals to each group. All animals were immunised with 1 ml (one dose) of the vaccine. The first group of 10 animals received no further booster vaccination, while the second group received a booster vaccination one month after the first dose. Blood samples were collected at 1, 7, 19, 24 and 48 months after first vaccination in order to monitor the antibody response.

Antibody assessment

Rapid Fluorescent Focus Inhibition Test (RFFIT) as described by SMITH et al. (1973) was used for estimation of antibody titres. SAD strain of rabies virus was used in the test.

Results and discussion

Antibody estimation was carried out by RFFIT and expressed as equivalent international units by using the WHO reference serum. Results are presented in Table 1. From the data, it can be noted that one animal in the single dose group showed a poor antibody response. All other animals in both groups showed a good immune response, with mean antibody titres ranging from 2.13±1.12 to 6.07±2.03 IU. The mean antibody levels of more than 0.5 IU were maintained for 48 months post-vaccination period. Only three animals in group I, and four animals in group II, were available for study at the end of a four-year post-vaccination period, and all animals had titres above 0.5 IU.

The immune response pattern seen in camels was similar to observations made in other species such as dogs and cattle (RAMANNA et al., 1991; RAMANNA and SRINIVASAN, 1992). The titres obtained and the duration of immunity observed in camels in the present study were different from the observations of WERNEY et al. (1994). High antibody titres were observed at 1 and 7 months after first vaccination, and thereafter a gradual reduction in the titres was noticed in 60% of the animals. The reason for this could be the difference in the breeds of camel used in the study, or the individual animal's response to the vaccine. Initial induction of high antibody titres probably maintained the antibody level for a longer period, as observed in the present study, which lasted for 4 years.

Table 1. Antibody titres (IU) obtained in camels (Camelus dromedarius) at different time intervals post-vaccination with inactivated rabies vaccine

ND= not done

In an earlier study, SOULEBOT et al. (1985) recorded satisfactory antibody titres in cattle immunised with a single dose of vaccine over a three-year period. The present study indicated that seroconversion in camels was satisfactory and that the duration of immunity was fairly long, as indicated by serum antibody titres above protection levels up to the four-year point.

References

BLOCK, N., I. DIALLO (1995): A probable outbreak of rabies in a group of camels in Niger. Vet. Microbiol. 46, 281-284.

RAMANNA, B. C., A. P. KALANIDHI, V. A. SRINIVASAN, L. BRUCKNER, U. KIHM (1991): A tissue culture rabies vaccine. Indian Vet. J. 68, 803-807.

RAMANNA, B. C., V. A. SRINIVASAN (1992): Serological response in cattle to tissue culture rabies vaccine. Indian Vet. J. 69, 8-10.

SMITH, J. S., P. A. YAGER, G. M. BAER (1973): A rapid reproducible test for determining rabies neutralizing antibody. Bull. Wld. Hlth. Org. 48, 535-541.

SOULEBOT, J. P., P. PRECAUSTA, A. BRUN, J. M. BLANCOU, M. PEPIN, G. CHAPPUIS, H. G. PETERMANN (1985): Immunization of herbivores against rabies using an inactivated cell culture vaccine. In: Rabies in Tropics (E. Kuwert et al., Eds.). Springer-Verlag. Berlin, Heidelberg.

WERNEY, U., J. AKBAR, J. COX (1994): Rabies antibody titres in vaccinated dromedary camel: a preliminary study. J. Camel Practice and Res. June.

Received: 12 August 1997
Accepted: 10 June 1998

KALANIDHI, A. P., U. K. BISSA, V. A. SRINIVASAN: Seroloski odgovor i trajanje imunosti u deva cijepljenih protiv bjesnoce inaktiviranom vakcinom pripravljenom od virusa uzgojenog u stanicnoj kulturi. Vet. arhiv 68, 81-84, 1998.

SAZETAK

Istrazivanje je bilo provedeno na devama (Camelus dromedarius) cijepljenima jednom ili dvjema dozama inaktivirane vakcine protiv bjesnoce. Seroloski odgovor i trajanje imunosti bili su promatrani tijekom 48 mjeseci nakon vakcinacije. Brzim testom inhibicije fluorescirajucih zarista ustanovljen je dobar seroloski odgovor. Mjesec dana poslije vakcinacije titri protutijela su kolebali od 2,13±1,2 do 6,07±2,03 internacionalnih jedinica (IJ), a zadrzali su se na razini vecoj od 0,5 IJ i 48 mjeseci poslije vakcinacije u obje skupine zivotinja. Istrazivanje je pokazalo da je inaktivirana vakcina protiv bjesnoce pripravljena od virusa umnozenog u stanicnoj kulturi potakla zadovoljavajuci imunosni odgovor u deva promatranih u tijeku 48 mjeseci.

Kljucne rijeci: jednogrba deva, Camelus dromedarius, seroloski odgovor, profilaksa, Raksharab, Indija