A Protectotype Trial for the Control of the Q1 Infectious Bronchitis Virus
(IBV) Variant Strain in South America
Abstract Author(s): Luiz Sesti1, Héctor Ramón Sanguinetti2, Carlo R.
Zenobi2, María Victoria Terrera2, Mariana Jauregui2, Jorge Chacón1, Lucas
Sara1, Pascal Paulet1
Abstract Affiliation(s): 1 Ceva Animal Health – Argentina, Brazil, France 2
SENASA (Servicio Nacional de Sanidad y Calidad Agroalimentaria) – Argentina
In the recent years, a new IBV field strain, the Chinese variant strain “Q1” (also
known as “J2” or “T3”) has been detected in several countries in South America.
Its isolation and molecular detection was well correlated with field clinical
problems occurring in many companies in Chile, Peru and Argentina. The Q1
strain presents a genetic similarity (S1 protein gene) of about 77% with the M41
standard Massachusetts strain (Mass). A protectotype trial was conducted in
order to determine the level of protection induced against the Q1 IBV variant
strain circulating in several countries in South America. SPF birds were eye drop
vaccinated at day 1 with two vaccination programs (group 1 and group 2) using a
combination of Mass-type live vaccines (two different commercial products) and
793/B-type IBV variant live vaccines (two different commercial products; 80% S1
gene similarity with the Q1 variant strain). Two other groups of SPF birds (group
3 and group 4) were used as positive control (challenged not vaccinated) and
negative control (not challenged, not vaccinated). Birds were intratracheally
challenged (groups 1, 2 and 3) at 25 days of age with an Argentinian isolate of
the Q1 IBV variant (INTA BI-1308) which was isolated from broilers in a broiler
production company located in the northeast region of the country. Protection
against the Q1 challenge was assessed at days 30 and 31 of age through:
clinical score, daily body weight gain, ciliostasis score test, challenge virus
shedding measured by qRT-PCR and histopathological lesion score in trachea
and kidney. Results from the two vaccination programs indicated that both
vaccination programs with 793/B-type vaccines presented evident protection
against the Q1 field variant although some difference was detected between the
vaccine combinations.

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