Infectious laryngotracheitis virus in chickens

Area of Science:

• Veterinary Virology
• Poultry Pathology
• Disease Control

Background:

• Infectious laryngotracheitis (ILT) is a significant respiratory disease in chickens, causing substantial global economic losses.
• ILT virus (ILTV), an alphaherpesvirus, transmits through respiratory and ocular routes, presenting in severe (bloody trachea, high mortality) and mild (nasal discharge, conjunctivitis) forms.

Purpose of the Study:

• To review diagnostic methods for ILTV detection and differentiation.
• To discuss the implications of vaccine-derived ILTV strains in disease outbreaks.
• To highlight strategies for effective ILT control in poultry.

Main Methods:

• Review of diagnostic techniques including conventional PCR, nested PCR, real-time PCR, and loop-mediated isothermal amplification.
• Application of PCR combined with restriction fragment length polymorphism (RFLP) for genetic grouping of ILTV.
• Analysis of vaccine efficacy and potential for reversion to virulence.

Main Results:

• Various molecular methods effectively detect ILTV in infected birds.
• PCR-RFLP distinguishes between vaccine and wild-type ILTV strains.
• Evidence suggests virulent field ILTV can arise from the reversion of modified-live vaccines, leading to farm outbreaks.

Conclusions:

• Modified-live vaccine reversion is a significant source of ILT outbreaks.
• While new recombinant vaccines offer promise, improved biosecurity and farm management are essential for ILT control in endemic areas.