Virulence Properties of GI-23 Infectious Bronchitis Virus Isolated in Poland and Efficacy of Different Vaccination strategies

Abstract

Infectious bronchitis virus (IBV) is one of the most important poultry pathogens, leading significant economic losses worldwide. IBV is characterised by highly genetic, serotype, and pathotypic variability. Despite extensive immunoprophylaxis strategies, the emergence of new genetic lineages is frequently observed in the field, causing disease control to be more complicated. In the last decade, the spread of variants assigned to the GI-23 lineage of IBV (formerly known as Var2) started from Middle-Eastern countries and reached Europe in the last few years. Recently, the introduction and fast spread of Var2-like IBVs in Poland was reported. In this study, the virulence properties and efficacy of different vaccination programmes were evaluated against infection with the IBV GI-23 strain gammaCoV/Ck/Poland/G052/2016. The pathogenicity of the Var2 isolate was conducted in one-day-old and three-week-old SPF chickens and showed that the course of the disease is age dependent. Seven vaccination programmes using Mass, 793B, QX alone or in combination, and Var2 live vaccines were tested against the GI-23 infectious bronchitis virus challenge. All groups were scored according to the ciliostasis test at 5 days post challenge. Two immunoprophylaxis strategies generated full protection against gammaCoV/Ck/Poland/G052/2016 infection—Var2 and Mass used in one-day-old chickens boosted by a combination of the QX and 793B vaccine (both with a ciliostasis score of 0 and 100% protection).

Pathogenicity of GI-23 Avian Infectious Bronchitis Virus Strain Isolated in Brazil

“…Lesions observed in the lungs occurred inconsistently, being present in only a few birds and, to a mild degree, agreeing with Lisowska et al (2021) [ 37 ]. Our trials have shown that IBV rarely causes lung damage.…”

“…Zanaty et al (2016) [ 36 ] concluded that the most severe clinical symptoms of IBV appear in very young chicks and the severity decreases in older chickens. Lisowska et al (2021) [ 37 ] agree with that, summarizing that the pathogenicity of GI-23 is more severe in young birds. To Awad et al (2016) [ 38 ], the disease was of a lesser severity in broilers compared to SPF chicks, reflecting the inhibitory effects of the IBV maternal antibodies or genetic/strain susceptibility, or both.…”

Emergence and molecular characterization of the avian infectious bronchitis virus GI‐23 in commercial broiler farms from South America

“…GI‐23 seems to have initially disseminated in the Middle Eastern countries and after reached Europe and Africa in the last decade (Houta et al., 2021). Due to the important economic losses to the poultry industry, different vaccination programmes have been developed for this lineage (Abozeid & Naguib, 2020; Lisowska et al., 2021). The present study aimed to describe the emergence and molecular characteristics of GI‐23 strains recently detected in Brazil (the first report in South America) as well as the rapid spread in commercial broiler farms in the southern region of the country.…”

Phylodynamic and Recombination Analyses of Avian Infectious Bronchitis GI-23 Reveal a Widespread Recombinant Cluster and New Among-Countries Linkages

“…A decline followed the intense rise, probably due to effective control measures implementation and crescent population immunity. A second major peak was observed after GI-23 viruses introduction to Europe, where a naïve host population was present, and the implementation of specific vaccination strategies was limited and tardive, or even totally absent [ 30 , 49 ]. Additionally, more intense diagnostic sequencing activity in European countries likely contributed to an overrepresentation of available sequences.…”

“…Interestingly, European poultry populations are mainly vaccinated with a combination of Mass plus 793B or Mass plus QX vaccines to protect against the highly prevalent QX field strains [ 49 ]. Although cross-protection was demonstrated experimentally, this issue deserves to be further investigated as it is unclear whether these vaccinations display a limited efficacy against GI-23 in field conditions or if a difference exists between the protocols that could justify the expansion of GI-23 in Europe [ 45 , 49 ].…”