Resistance to three pathogens in the endangered winter-run chinook salmon (Oncorhynchus tshawytscha): effects of inbreeding and major histocompatibility complex genotypes

2002 ◽  
Vol 59 (6) ◽  
pp. 966-975 ◽  
Author(s):  
Kristen D Arkush ◽  
Alan R Giese ◽  
Holly L Mendonca ◽  
Anne M McBride ◽  
Gary D Marty ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Genetic Resistance ◽  
Vibrio Anguillarum ◽  
Major Histocompatibility ◽  
Necrosis Virus ◽  
Histocompatibility Complex ◽  
Infectious Hematopoietic Necrosis ◽  
Lower Infection

We have carried out the first major infectivity trial to examine differential genetic resistance in fish for pathogens. We used captive-bred, endangered winter-run chinook salmon (Oncorhynchus tshawytscha) to determine resistance to three pathogens: the bacterium, Listonella (Vibrio) anguillarum, infectious hematopoietic necrosis virus (IHNV), and Myxobolus cerebralis, the parasite that causes whirling disease. We compared resistance to these three pathogens between inbred and outbred salmon and between siblings that were heterozygous or homozygous for a class II gene in the major histocompatibility complex (MHC). In two of five different comparisons, we found significant genetic effects on disease resistance. First, MHC heterozygotes had a higher survival than MHC homozygotes when exposed to IHNV and the selection disadvantage of homozygotes was estimated to be 8.5%. Second, outbred fish had a higher resistance (or lower infection severity) than inbred fish when exposed to M. cerebralis. Using a quantitative genetics approach, it appears that there are slightly more than three gene equivalents segregating that would result in no resistance to M. cerebralis when homozygous. Overall, our investigation suggests that pathogen susceptibility in the winter-run chinook salmon will increase if further genetic variation is lost in this endangered species.

scholarly journals Sexual conflict inhibits female mate choice for major histocompatibility complex dissimilarity in Chinook salmon

2009 ◽  
Vol 277 (1683) ◽  
pp. 885-894 ◽  
Author(s):  
Shawn R. Garner ◽  
Romina N. Bortoluzzi ◽  
Daniel D. Heath ◽  
Bryan D. Neff
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Sexual Conflict ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Mating Behaviour ◽  
Female Mate Choice ◽  
Major Histocompatibility ◽  
Male Harassment ◽  
Histocompatibility Complex

In many species females prefer major histocompatibility complex (MHC) dissimilar mates, which may improve offspring resistance to pathogens. However, sexual conflict may interfere with female preference when males attempt to mate with all females, regardless of compatibility. Here we used semi-natural spawning channels to examine how mating behaviour and genetic similarity at the MHC class II peptide binding region affected parentage patterns in Chinook salmon ( Oncorhynchus tshawytscha ). We found that females directed aggression at more MHC-similar males than expected by chance, providing a possible mechanism of female MHC choice in salmon. Males also directed aggression towards MHC-similar females, which was consistent with males harassing unreceptive mates. Males' aggression was positively correlated with their reproductive success, and it appeared to overcome female aversion to mating with MHC-similar males, as females who were the target of high levels of male aggression had lower than expected MHC divergence in their offspring. Indeed, offspring MHC divergence was highest when the sex ratio was female-biased and male harassment was likely to be less intense. These data suggest that male harassment can reduce female effectiveness in selecting MHC-compatible mates, and sexual conflict can thus have an indirect cost to females.

scholarly journals Virulence and Infectivity of UC, MD, and L Strains of Infectious Hematopoietic Necrosis Virus (IHNV) in Four Populations of Columbia River Basin Chinook Salmon

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 701
Author(s):  
Daniel G. Hernandez ◽  
William Brown ◽  
Kerry A. Naish ◽  
Gael Kurath
Keyword(s):  
River Basin ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Columbia River ◽  
Infectious Hematopoietic Necrosis Virus ◽  
Host Susceptibility ◽  
Columbia River Basin ◽  
Species Variation ◽  
Necrosis Virus ◽  
Infectious Hematopoietic Necrosis

Infectious Hematopoietic Necrosis Virus (IHNV) infects juvenile salmonid fish in conservation hatcheries and aquaculture facilities, and in some cases, causes lethal disease. This study assesses intra-specific variation in the IHNV susceptibility of Chinook salmon (Oncorhynchus tshawytscha) in the Columbia River Basin (CRB), in the northwestern United States. The virulence and infectivity of IHNV strains from three divergent virus genogroups are measured in four Chinook salmon populations, including spring-run and fall-run fish from the lower or upper regions of the CRB. Following controlled laboratory exposures, our results show that the positive control L strain had significantly higher virulence, and the UC and MD strains that predominate in the CRB had equivalently low virulence, consistent with field observations. By several experimental measures, there was little variation in host susceptibility to infection or disease. However, a small number of exceptions suggested that the lower CRB spring-run Chinook salmon population may be less susceptible than other populations tested. The UC and MD viruses did not differ in infectivity, indicating that the observed asymmetric field prevalence in which IHNV detected in CRB Chinook salmon is 83% UC and 17% MD is not due to the UC virus being more infectious. Overall, we report little intra-species variation in CRB Chinook salmon susceptibility to UC or MD IHNV infection or disease, and suggest that other factors may instead influence the ecology of IHNV in the CRB.

scholarly journals Major Histocompatibility Complex Differentiation in Sacramento River Chinook Salmon

Genetics ◽  
1999 ◽  
Vol 151 (3) ◽  
pp. 1115-1122
Author(s):  
Timothy J Kim ◽  
Karen M Parker ◽  
Philip W Hedrick
Keyword(s):  
Major Histocompatibility Complex ◽  
Chinook Salmon ◽  
Binding Sites ◽  
River System ◽  
Amino Acid Replacement ◽  
Sacramento River ◽  
Antigen Binding ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Selection For

Abstract The chinook salmon of the Sacramento River, California, have been reduced to a fraction of their former abundance because of human impact and use of the river system. Here we examine the genetic variation at a major histocompatibility complex class II exon in the four Sacramento chinook salmon runs. Examination of the alleles found in these and other chinook salmon revealed nucleotide patterns consistent with selection for amino acid replacement at the putative antigen-binding sites. We found a significant amount of variation in each of the runs, including the federally endangered winter run. All of the samples were in Hardy-Weinberg proportions. A significant amount of genetic differentiation between runs was revealed by several measures of differentiation. Winter run was the most genetically divergent, while the spring, late-fall, and fall runs were less differentiated.

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