Persistence of Maternal Antibodies in Calves Born to Dams Naturally Infected with Bovine Ephemeral Fever Virus
Persistence of Maternal Antibodies in Calves Born to Dams Naturally Infected with Bovine Ephemeral Fever Virus
S. A. Khalil1; M. El-Sayed2; M. M. El-Fayomy2; H. Y. Hassan3 and A. Zaghawa3
ABSTRACT
Bovine ephemeral fever virus (BEFV) is an arthropod born rhabdovirus which causes disabling febrile infection among cattle and water buffalo. The disease is characterized by inflammation of mesodermal tissue as achieved by muscular shivering, stiffness, lameness, and enlargement of the peripheral lymph nodes. Recently, the disease caused several outbreaks during 2000, 2001 and lastly 2004. The persistence of immunity after natural infection is varied from 6 months to several years. Assessment or maternal antibodies in calves born to naturally infected dams is a matter of interest in order to determine the proper time of vaccination. Twenty-five pregnant Frisian cows in the last stage of pregnancy were naturally infected with BEFV during the Egyptian outbreak in summer 2004. Four of them were aborted and excluded from experimental. The disease was diagnosed clinically and confirmed by the detection of BEFV antigen by Immunoperoxidase staining. The aim of the present study was to determine the efficiency of transfer of BEFV antibodies from naturally infected cows to newborn calves through colostrum. According to the level of serum neutralizing antibodies (SNA), the cows were allotted into three groups. In the first group (n=9). the mean SNA in naturally infected cows was 46.2. which gave a mean titer neutralizing antibodies (NA) of 28.4 in their colostrums. Calves fed on these colostrums had a mean SNA of 12.2. 6.9 and 2 after one week, one month, and 2 months, respectively. In the second group (n = 7) the mean SNA in naturally intucted cows was 12.6. which gave a mean neutralizing antibodies (NA) titer of 7.7 in their colostrums. Calves fed on these colostrums had a mean SNA of 3.7, 0.9, and 0.0 after one week, one month, and 2 months, respectively. In the third group (n=5). The mean SNA in naturally infected cows was 2.4, which gave a mean titer neutralizing antibodies (NA) of 0.8 in their colostrums. Calves fed on these colostrunrs had a mean SNA of 0.4. 0.0 and 0.0 after one week, one month, and 2 months, respectively. It could be concluded that: l) The level of SNA in the pregnant cows determines the level of NA in their colostrums. 2) The level or SNA in calves dependent on the level of NA in the colostrums taken beside the general rules of transfer of maternal immunity through colostrums as for esmnple the quantity and proper time of colostrums intake. 3) The assessment of SNA in calves is very essential to determine the proper time of vaccination especially after natural outbreak. This point needs further insestigation
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