Abstract
Avian infectious laryngotracheitis (ILT) is a worldwide infectious disease that causes important economic losses in the poultry industry. Although it is known that ILT virus (ILTV) is present in Argentina, there is no information about the circulating strains. With the aim to characterize them, seven different genomic regions (thymidine kinase, glycoproteins D, G, B, C, and J, and infected cell polypeptide 4) were partially sequenced and compared between field samples. The gJ sequence resulted to be the most informative segment, it allowed the differentiation among field sample strains, and also, between wild and vaccine viruses. Specific changes in selected nucleotidic positions led to the definition of five distinct haplotypes. Tests for detection of clustering were run to test the null hypothesis that ILTV haplotypes were randomly distributed in time in Argentina and in space in the most densely populated poultry region of this country, Entre Rios. From this study, it was possible to identify a 46 km radius cluster in which higher proportions of haplotypes 4 and 5 were observed, next to a provincial route in Entre Rios and a significant decline of haplotype 5 between 2009 and 2011. Results here provide an update on the molecular epidemiology of ILT in Argentina, including data on specific genome segments that may be used for rapid characterization of the virus in the field. Ultimately, results will contribute to the surveillance of ILT in the country.
Highlights
Infectious laryngotracheitis (ILT) is an acute and highly contagious respiratory disease of chicken that causes far-reaching financial losses due to its high mortality rate and reduction in egg production
Two types of ILT virus (ILTV) attenuated vaccines have been widely used to control the disease, namely, chicken embryo-origin (CEO) vaccine, which is attenuated by serial passages in ILTV: Molecular and Spatial Study embryonated eggs [3], and a tissue culture-origin (TCO) vaccine, which is generated by multiple passages in tissue culture [4]
Most (93%) of the 72 field samples were collected from the two provinces in which most of the poultry production is concentrated in Argentina, namely, Entre Rios (n = 39 samples, 54.2%) and Buenos Aires (n = 28 samples, 38.8%)
Summary
Infectious laryngotracheitis (ILT) is an acute and highly contagious respiratory disease of chicken that causes far-reaching financial losses due to its high mortality rate and reduction in egg production. Two types of ILTV attenuated vaccines have been widely used to control the disease, namely, chicken embryo-origin (CEO) vaccine, which is attenuated by serial passages in ILTV: Molecular and Spatial Study embryonated eggs [3], and a tissue culture-origin (TCO) vaccine, which is generated by multiple passages in tissue culture [4]. The ILTV is globally distributed and several epidemiological studies have been conducted in different countries for detecting circulating ILTVs. Traditionally, differentiation of wild from vaccine strains has been based on the use of restriction length polymorphism (RFLP) profiles of the complete genome [5,6,7,8]. Even in the absence of multiple ILTV serotypes, molecular characterizations is still epidemiologically useful to assess the virus dissemination process in a region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
