Vaccine or field strains: the jigsaw pattern of infectious bronchitis virus molecular epidemiology in Poland

Abstract

Infectious bronchitis (IB), caused by infectious bronchitis virus (IBV), account for severe economic losses in the poultry industry. The continuous emergence of a multitude of IBV variants poses many challenges for its diagnosis and control, and live attenuated vaccines, despite their routine use, still plays a significant role in driving IBV evolution, further complicating the epidemiological scenario. Unfortunately, the impact of different vaccination strategies on IB control, epidemiology, and diagnosis has rarely been investigated.This work presents the results of a large-scale diagnostic survey performed in Poland to study IBV molecular epidemiology and how vaccination may affect the viral circulation in the field. To this purpose, 589 samples were collected between May 2017 and January 2019, tested by reverse transcription-PCR for IBV and sequenced. Vaccine and field strains were discriminated based on genetic and anamnestic information.The most commonly detected lineages were 793B (79%) and variant 2 (17.4%), with sporadic detections of QX, Mass, and D274-like strains. Most of the detected strains had a vaccine origin: 46.3% matched one of the applied vaccines, while 36.5% were genetically related to vaccines not implemented in the respective protocol. Besides their practical value for the proper planning of vaccination protocols in Poland, these results suggest that only a fraction (17.2%) of the circulating strains are field ones, imposing a careful assessment of the actual IBV field menaces. Moreover, phenomena like vaccine spreading and persistence seem to occur commonly, stressing the need to further study the epidemiological consequences of the extensive use of live vaccines.

A Recombinant La Sota Vaccine Strain Expressing Multiple Epitopes of Infectious Bronchitis Virus (IBV) Protects Specific Pathogen-Free (SPF) Chickens against IBV and NDV Challenges

“…Avian infectious bronchitis (IB) is an acute and highly contagious viral respiratory disease of chickens. IB occurs worldwide and causes substantial economic losses in the poultry industry [1][2][3][4][5]. IB is caused by the infectious bronchitis virus (IBV) which belongs to the order Nidovirales, family Coronaviridae, genus Gammacoronavirus.…”

Infectious Bronchitis Virus Evolution, Diagnosis and Control

“…The absence of clear genetic markers also prevents the reliable discrimination between vaccine and field strains [ 72 ], although consistent genetic differences were sometimes demonstrated [ 73 , 74 , 75 ]. Anamnestic data like the presence of symptoms and vaccination schedule should thus be taken into account for more confident deductions.…”

“…In a typical field situation, the common adoption of multiple live vaccines may complicate the diagnostic process and mask the simultaneous presence of field strains [ 68 , 74 , 82 ]. For this reason, the implemented vaccination protocol should be taken into account while interpreting the results.…”

“…Because of the common persistence of the vaccines and the expected competition between vaccine and field strains for cellular receptors [ 68 , 82 ], the vaccine yield could be considered as a proxy of vaccination quality and protection, in addition to classical immunity assessment. Nevertheless, vaccination strategies in the field are often far from coherent, standardized or constant [ 74 , 126 ], even within the same country where the local epidemiological scenario is known. This heterogeneity hinders both the identification of field infections and the monitoring of vaccine intake.…”

A highly pathogenic GI-19 lineage infectious bronchitis virus originated from multiple recombination events with broad tissue tropism

“…viruses were also detected in France (Worthington et al, 2008;de Wit et al, 2018) and Germany in 2004 (Worthington et al, 2008); in Italy (Beato et al, 2005), the Netherlands (Worthington et al, 2008), and Slovenia in 2005 (Krapez et al, 2010); in Belgium (Worthington et al, 2008) and Poland in 2006(Domanska-Blicharz et al, 2006; in UK in 2007 (Gough et al, 2008;Irvine et al, 2010;Valastro et al, 2010); in Sweden and Denmark in 2009 (Abro et al, 2012); in Switzerland (Sigrist et al, 2012) and Finland in 2011 (Pohjola et al, 2014); and in Hungary in 2014 (Kiss et al, 2015). Genetically related viruses were also detected in Poland (de Wit et al, 2018;Legnardi et al, 2019), Spain, Portugal (de Wit et al, 2018, and Greece (Andreopoulou et al, 2019) in recent years. Since the first detection in Europe, the incidence of infection with GI-19 has increased in many European countries, and GI-19 has become the predominant genotype (Worthington et al, 2008;Krapez et al, 2011;Ovchinnikova et al, 2011;de Wit et al, 2018).…”