Uptake and spread of infectious laryngotracheitis vaccine virus within meat chicken flocks following drinking water vaccination

Groves, Peter J.; Williamson, Sarah; Sharpe, S. M.; Gerber, Priscilla F.; Gao, Yuanshuo K.; Hirn, Tabitha J.; Walkden‐Brown, Stephen W.

doi:10.1016/j.vaccine.2019.06.087

Cited by 19 publications

(17 citation statements)

References 16 publications

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“…This vaccine behavior could consequently be a hazard for young chicks, since it has been demonstrated that attenuated CIA strains have the potential to revert to virulent phenotypes after chicken-to-chicken transmission in the field [50,51]. Vaccine persistence, circulation and reversion to virulence have also been frequently reported for other empirically attenuated avian vaccines developed to control immunosuppressive or respiratory diseases [52][53][54]. Next-generation vaccines, with improved stability and safety, are currently under study and development for most avian pathogens and, in the future, they will likely replace traditional vaccines [55][56][57][58].…”

Section: Discussionmentioning

confidence: 93%

Genetic Heterogeneity among Chicken Infectious Anemia Viruses Detected in Italian Fowl

Quaglia

Mescolini

Catelli

et al. 2021

Animals

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Chicken infectious anemia virus (CIAV) is a pathogen of chickens associated with immunosuppression and with a disease named chicken infectious anemia. The present survey reports an epidemiological study on CIAV distribution in Italian broiler, broiler breeder and backyard chicken flocks. Twenty-five strains were detected by a specifically developed nested PCR protocol, and molecularly characterized by partial VP1 gene or complete genome sequencing. Viral DNA amplification was successfully obtained from non-invasive samples such as feathers and environmental dust. Sequence and phylogenetic analysis showed the circulation of field or potentially vaccine-derived strains with heterogeneous sequences clustered into genogroups II, IIIa, and IIIb. Marker genome positions, reported to be correlated with CIAV virulence, were evaluated in field strains. In conclusion, this is the first survey focused on the molecular characteristics of Italian CIAVs, which have proved to be highly heterogeneous, implementing at the same time a distribution map of field viruses worldwide.

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Section: Discussionmentioning

confidence: 93%

Genetic Heterogeneity among Chicken Infectious Anemia Viruses Detected in Italian Fowl

Quaglia

Mescolini

Catelli

et al. 2021

Animals

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“…These data are suggestive of strain differences in mode of transmission between the Australian ILTV strains with vaccine viruses transmitting very effectively to in-contact birds while virulent virus is more effective at airborne transmission. However, Groves et al [ 6 ] reported comparatively slow spread of the Serva vaccine virus to in-contact birds in large commercial poultry houses following sub-optimal initial vaccine take indicating that effective spread between chickens should not be relied upon to compensate for sub-optimal mass vaccination methods. The difference between these findings in the field and our experimental results may be due to the vast difference in population sizes involved in the two studies and also the different route of infection used for the primary infection.…”

Section: Discussionmentioning

confidence: 99%

“…In Australia, ILT remains a disease of significant concern to the broiler chicken industry due to a prolonged outbreak in high producing areas in Victoria and New South Wales (NSW) that has not been brought under adequate control, despite the availability and use of live vaccines [ 6 , 7 ]. In Australia only live attenuated vaccines are available, these being Australian chick embryo origin (CEO) vaccines SA2 and A20 (SA2 strain further attenuated by 20 passages in cell culture and then 5 passages in embryonated eggs) [ 8 ] and European strain Serva.…”

Section: Introductionmentioning

confidence: 99%

“…ILTV can be transmitted horizontally through the respiratory, conjunctival or to a lesser extent oral routes [ 16 – 19 ]. Recent studies have demonstrated that live ILT vaccines transmit readily from infected to susceptible in-contact chickens experimentally [ 20 – 22 ] and in the field [ 6 ]. Direct physical contact between chickens may be important in transmission of ILTV as infected birds have a high incidence of conjunctivitis following infection by eye drop [ 23 ], or airborne transmission [ 24 ].…”

Section: Introductionmentioning

confidence: 99%

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Transmission of infectious laryngotracheitis virus vaccine and field strains: the role of degree of contact and transmission by whole blood, plasma and poultry dust

Yegoraw

Assen

Gerber

et al. 2021

Vet Res

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Understanding the mechanisms of transmission of infectious laryngotracheitis virus (ILTV) is critical to proper control as both vaccine and wild-type strains circulate within chicken flocks with potential adverse consequences. The relative efficiency of transmission by direct contact between chickens and airborne transmission has not been investigated. Furthermore, relatively high levels of ILTV DNA have been detected in poultry dust and blood but the infectivity of these is unknown. In this study, comparison of in-contact and airborne transmission of two vaccine and one field strain of ILTV revealed that all transmitted to 100% of in-contact birds by 6 days post-exposure (dpe). Airborne transmission without contact resulted in 100% transmission by 14 and 17 dpe for the wild-type and Serva vaccine virus but only 27% transmission by 21 dpe for the A20 vaccine virus. The infectivity of dust or extracts of dust and blood or plasma from infected chickens at various stages of infection was assessed by inoculation into susceptible chickens. There was no transmission by any of these materials. In conclusion, direct contact facilitated efficient ILTV transmission but the virus was unable to be transmitted by dust from infected chickens suggestive of a limited role in the epidemiology of ILTV.

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“…Attenuated vaccine virus is also prone to reversion to virulence by multiple passages through bird-to-bird transmission within the flock. This event is reported more often among CEO vaccines given the lower degree of attenuation in comparison to TCO vaccines [10][11][12].…”

Section: Introductionmentioning

confidence: 93%

Analysis of Whole-Genome Sequences of Infectious laryngotracheitis Virus Isolates from Poultry Flocks in Canada: Evidence of Recombination

Contreras

Meer

Checkley

et al. 2020

Viruses

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Infectious laryngotracheitis virus (ILTV) is a herpes virus that causes an acute respiratory disease of poultry known as infectious laryngotracheitis (ILT). Chicken embryo origin (CEO) and tissue culture origin (TCO) live attenuated vaccines are routinely used for the control of ILT. However, vaccine virus is known to revert to virulence, and it has been recently shown that ILT field viral strains can undergo recombination with vaccinal ILTV and such recombinant ILT viruses possess greater transmission and pathogenicity potential. Based on complete or partial genes of the ILTV genome, few studies genotyped ILTV strains circulating in Canada, and so far, information is scarce on whole-genome sequencing or the presence of recombination in Canadian ILTV isolates. The objective of this study was to genetically characterize the 14 ILTV isolates that originated from three provinces in Canada (Alberta, British Columbia and Quebec). To this end, a phylogenetic analysis of 50 ILTV complete genome sequences, including 14 sequences of Canadian origin, was carried out. Additional phylogenetic analysis of the unique long, unique short and inverted repeat regions of the ILTV genome was also performed. We observed that 71%, 21% and 7% of the ILTV isolates were categorized as CEO revertant, wild-type and TCO vaccine-related, respectively. The sequences were also analyzed for potential recombination events, which included evidence in the British Columbia ILTV isolate. This event involved two ILTV vaccine (CEO) strains as parental strains. Recombination analysis also identified that one ILTV isolate from Alberta as a potential parental strain for a United States origin ILTV isolate. The positions of the possible recombination breakpoints were identified. These results indicate that the ILTV wild-type strains can recombine with vaccinal strains complicating vaccine-mediated control of ILT. Further studies on the pathogenicity of these ILTV strains, including the recombinant ILTV isolate are currently ongoing.

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Uptake and spread of infectious laryngotracheitis vaccine virus within meat chicken flocks following drinking water vaccination

Cited by 19 publications

References 16 publications

Genetic Heterogeneity among Chicken Infectious Anemia Viruses Detected in Italian Fowl

Genetic Heterogeneity among Chicken Infectious Anemia Viruses Detected in Italian Fowl

Transmission of infectious laryngotracheitis virus vaccine and field strains: the role of degree of contact and transmission by whole blood, plasma and poultry dust

Analysis of Whole-Genome Sequences of Infectious laryngotracheitis Virus Isolates from Poultry Flocks in Canada: Evidence of Recombination

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