Impact of vaccination and selective breeding on the transmission of Infectious salmon anemia virus

Chase-Topping, Margo; Pooley, Christopher; Moghadam, Hooman K.; Hillestad, Borghild; Lillehammer, Marie; Sveen, Lene; Doeschl‐Wilson, Andrea

doi:10.1016/j.aquaculture.2021.736365

Cited by 13 publications

(13 citation statements)

References 33 publications

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“…Although the experiment lacked statistical power to provide precise estimates for genetic effects, it revealed that high genetic resistance may not necessarily confer beneficial effects on the epidemiological traits, as previously indicated for resistance of Atlantic salmon to the IPN virus [ 25 ]. Similar findings were reported in a recent small-scale porcine reproductive and respiratory syndrome (PRRS) virus transmission experiment in pigs to assess the effects of the previously identified GBP5 PRRS resistance gene on pigs’ susceptibility and infectivity under natural conditions [ 34 , 36 ]. That experiment adopted a multi-group mixed design, but also used barcoding of the virus to track pig genotype-specific transmission routes in order to increase statistical power.…”

Section: Discussionsupporting

confidence: 74%

“…( 1)), more replicates with smaller groups was found to be beneficial (especially true for the estimate of the SNP effect on infectivity). 29 To the best of our knowledge, to date relatively few animal disease transmission experiments have been conducted to specifically estimate host genetic effects on epidemiological traits [25,34,35]. Due to logistic restrictions on the number of contact groups, a multi-group pure design was used in a recent experiment involving infectious salmon anemia virus transmission in Atlantic salmon [34].…”

Section: Discussionmentioning

confidence: 99%

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Optimal experimental designs for estimating genetic and non-genetic effects underlying infectious disease transmission

Pooley

Marion

Bishop³

et al. 2022

Genet Sel Evol

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Background The spread of infectious diseases in populations is controlled by the susceptibility (propensity to acquire infection), infectivity (propensity to transmit infection), and recoverability (propensity to recover/die) of individuals. Estimating genetic risk factors for these three underlying host epidemiological traits can help reduce disease spread through genetic control strategies. Previous studies have identified important ‘disease resistance single nucleotide polymorphisms (SNPs)’, but how these affect the underlying traits is an unresolved question. Recent advances in computational statistics make it now possible to estimate the effects of SNPs on host traits from epidemic data (e.g. infection and/or recovery times of individuals or diagnostic test results). However, little is known about how to effectively design disease transmission experiments or field studies to maximise the precision with which these effects can be estimated. Results In this paper, we develop and validate analytical expressions for the precision of the estimates of SNP effects on the three above host traits for a disease transmission experiment with one or more non-interacting contact groups. Maximising these expressions leads to three distinct ‘experimental’ designs, each specifying a different set of ideal SNP genotype compositions across groups: (a) appropriate for a single contact-group, (b) a multi-group design termed “pure”, and (c) a multi-group design termed “mixed”, where ‘pure’ and ‘mixed’ refer to groupings that consist of individuals with uniformly the same or different SNP genotypes, respectively. Precision estimates for susceptibility and recoverability were found to be less sensitive to the experimental design than estimates for infectivity. Whereas the analytical expressions suggest that the multi-group pure and mixed designs estimate SNP effects with similar precision, the mixed design is preferred because it uses information from naturally-occurring rather than artificial infections. The same design principles apply to estimates of the epidemiological impact of other categorical fixed effects, such as breed, line, family, sex, or vaccination status. Estimation of SNP effect precisions from a given experimental setup is implemented in an online software tool SIRE-PC. Conclusions Methodology was developed to aid the design of disease transmission experiments for estimating the effect of individual SNPs and other categorical variables that underlie host susceptibility, infectivity and recoverability. Designs that maximize the precision of estimates were derived.

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Section: Discussionsupporting

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Optimal experimental designs for estimating genetic and non-genetic effects underlying infectious disease transmission

Pooley

Marion

Bishop³

et al. 2022

Genet Sel Evol

Self Cite

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“…Recent reviews report that fish vaccines often suffer from low efficacy, i.e., they lead to noticeable reduction but not to zero mortality, indicating that many fish vaccines are leaky and do not prevent pathogen transmission ( Adams, 2019 , Bøgwald and Dalmo, 2019 ). This was confirmed in a recent transmission trial that assessed vaccination effects on the transmission of Infectious Salmon Anaemia ( ISA ) virus in Atlantic salmon, which showed that ISA vaccination reduced, but did not prevent, pathogen transmission and mortality ( Chase-Topping et al, 2021 ). The study also demonstrates that even small-scale transmission experiments can quantify vaccine effects on the transmission of infection and herd resilience parameters from mortality records alone when coupled with epidemiological models, as predicted by simulation studies ( Pooley et al, 2020 ).…”

Section: Effects Of Vaccines On Herd Resiliencementioning

confidence: 71%

Review: Livestock disease resilience: from individual to herd level

Doeschl‐Wilson

Knap

Opriessnig

et al. 2021

Animal

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Infectious diseases are a major threat to the sustainable production of high-producing animals. Control efforts, such as vaccination or breeding approaches often target improvements to individual resilience to infections, i.e., they strengthen an animal’s ability to cope with infection, rather than preventing infection per se . There is increasing evidence for the contribution of non-clinical carriers (animals that become infected and are infectious but do not develop clinical signs) to the overall health and production of livestock populations for a wide range of infectious diseases. Therefore, we strongly advocate a shift of focus from increasing the disease resilience of individual animals to herd disease resilience as the appropriate target for sustainable disease control in livestock. Herd disease resilience not only captures the direct effects of vaccination or host genetics on the health and production performance of individuals but also the indirect effects on the environmental pathogen load that herd members are exposed to. For diseases primarily caused by infectious pathogens shed by herd members, these indirect effects on herd resilience are mediated both by individual susceptibility to infection and by characteristics (magnitude of infectiousness, duration of infectious period) that influence pathogen shedding from infected individuals. We review what is currently known about how vaccination and selective breeding affect herd disease resilience and its underlying components, and outline the changes required for improvement. To this purpose, we also seek to clarify and harmonise the terminology used in the different animal science disciplines to facilitate future collaborative approaches to infectious disease control in livestock.

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“…Use of ISAV vaccines in these populations did not prevent infection but may have contributed to (i) lower mortality rates than expected in an unvaccinated population (Chase‐Topping et al., 2021) and (ii) maintaining fish mortalities below the threshold of reporting requirements (3%) in NL (NL FFA, n.d.). Protection provided by ISAV vaccines might have also contributed to reduced ISAV transmission and consequently containing the outbreak to a single BMA (Chase‐Topping et al., 2021). Enhancements in farm‐level biosecurity and early ISAV detection strategies in July of 2020 may also have been mitigating factors for infection spread.…”

Section: Discussionmentioning

confidence: 83%

Descriptive epidemiology of variants of infectious salmon anaemia virus in four Atlantic salmon farms in Newfoundland and Labrador, Canada

Romero

Gardner

Hammell

et al. 2022

Journal of Fish Diseases

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Infectious salmon anaemia virus (ISAV) belongs to the FamilyOrthomyxoviridae and is the sole member of the Genus Isavirus (International Committee on Taxonomy of Viruses, 2020). The virus genome is comprised of eight single-stranded RNA segments coding for at least 10 proteins. Among the proteins encoded, there are two surface glycoproteins: haemagglutinin-esterase (HE), responsible for receptor-binding and receptor-destruction, and a fusion (F) protein (Aspehaug et al., 2005;Clouthier et al., 2002;Falk et al., 1997;Rimstad et al., 2011). The HE protein is encoded by gene segment 6, in which a highly polymorphic region (HPR) has been identified (Falk et al., 2004;Mjaaland et al., 2002). This segment has been used for genotyping purposes and identification of different

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Impact of vaccination and selective breeding on the transmission of Infectious salmon anemia virus

Cited by 13 publications

References 33 publications

Optimal experimental designs for estimating genetic and non-genetic effects underlying infectious disease transmission

Optimal experimental designs for estimating genetic and non-genetic effects underlying infectious disease transmission

Review: Livestock disease resilience: from individual to herd level

Descriptive epidemiology of variants of infectious salmon anaemia virus in four Atlantic salmon farms in Newfoundland and Labrador, Canada

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