Infectious Laryngotracheitis Virus from Field Outbreaks in Layer Birds: A Review
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Date
2018-04
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Abstract
Infectious laryngotracheitis (ILT) herpes virus continues to cause outbreaks of respiratory disease in chickens world-wide and is an important respiratory disease of chickens. In India and Asian countries, sporadic cases of ILT occur in all classes of birds, starting from commercial laying hens and hobby/show/game chickens, broilers and heavy breeders. The epornitics of ILT tend to occur where there are large populations of unvaccinated birds, i.e., in concentrated areas of layer production. ILT virus (ILTV) belongs to Alphaherpesvirinae and the Gallid herpesvirus 1 species. The transmission of ILTV is via respiratory and ocular routes. Layers which are endemic infected with ILT virus occur only in some regions of countries or even in particular multiple-age production farms where modified live vaccines are actually used, even though these biological products, as well as wild ILTV strains, can establish latent infections. Vaccination is a common method to prevent ILT. However, field isolates and vaccine viruses can establish latent infected carriers. According to PCR-RFLP results, virulent field ILTVs can be derived from modified-live vaccines. Therefore, modified-live vaccine reversion provides a source for ILT outbreaks on chicken farms. Two recently licensed commercial recombinant ILT vaccines are also in use. Presently recombinant and gene-deficient vaccine candidates are in the developmental stages and offer some hope for the control of this disease. However, in ILT endemic regions, improved biosecurity and management practices are critical for improved ILT control especially in our country where the import of these type of vaccines are still in the bay.
Description
TNV_SIJVS_2018_5(4)1-11
Keywords
Veterinary Science