Papers by Ruben Avendaño-Herrera
Brazilian Journal of Biology, Feb 1, 2009
Identification and Characterization of the Iron Uptake System in Different Chilean Renibacterium Salmoninarum Isolates and Its Influence on Pathogenesis and Inmunogenicity in Atlantic Salmon and Rainbow Trout
Diseases of Aquatic Organisms, Dec 22, 2008
The sensitivity of 4 published primer pairs for the detection of Streptococcus phocae strains was... more The sensitivity of 4 published primer pairs for the detection of Streptococcus phocae strains was evaluated. Primer sets cpn60-F and-R and sodA-F and-R correctly identified S. phocae. Correct identification was also achieved with the primer pairs cae1-cae2 and PX1-PX2, but using the reverse complementary version of both reverse primers (caeVQ2 and PXVQ2, respectively). Among the 4 PCR protocols with pure and mixed cultures, the primer pair PX1-PXVQ2 provided the highest level of sensitivity for S. phocae (10 2 and 10 4 cells per PCR tube), and detection was 10-to 100-fold higher than the other 3 primer pairs. When the cae1-caeVQ2 and PX1-PXVQ2 PCR protocols were applied to different seeded Atlantic salmon tissues (spleen, kidney and liver), the detection limit achieved was 5.1 × 10 5 to 6.4 × 10 7 CFU g-1 , and the lowest sensitivity detected was 1.18 × 10 6 S. phocae per tube (which corresponds to 6.4 × 10 7 CFU g-1) in spleen samples using PX1-PXVQ2. In the kidney samples seeded with S. phocae strains, regardless of the primer set used, the PCR sensitivity was the same (7.31 ± 1.5 × 10 6 CFU g-1). In addition, the nested PCR assay using the primer pair PX1-PXVQ2 improved the sensitivity of detection of S. phocae by at least 100 times compared to the first round PCR, not only in mixed and pure suspensions, but also in experimentally seeded fish tissues. The picked tissues that allowed the easiest detection of S. phocae were the liver, kidney and spleen, respectively. Thus, the nested PCR approach is an important tool for the rapid and reliable diagnosis of streptococcosis due to S. phocae.
Aquaculture Research, Nov 14, 2015
Aquaculture, Oct 1, 2018
Chile is the second largest global producer of farmed salmon. With a yearly production of over 70... more Chile is the second largest global producer of farmed salmon. With a yearly production of over 700 thousand tons and export value near US$4,000MM, farmed salmon ranks as Chile's second primary export after copper and accounts for 36% of all food exports. The salmon farming industry consequently creates an entire economy that provides direct and indirect employment for many southern regions of the country, with some cities and coastal communities being strongly dependent on this sector. In fact, more than 70,000 individuals, many living in remote areas, are either directly or indirectly employed by the salmon industry (Mardones et al. 2018). In recent years, the Chilean salmon farming industry has suffered important monetary losses and increasing production costs, particularly during the marine-fattening phase. These losses are due to disease outbreaks, the consequences of which further extend to environmental concerns as a result of antibiotic improper use/overuse in treating fish. Piscirickettsiosis, an endemic disease
Journal of Fish Diseases, Apr 1, 2009
Characterization of 20 Flavobacterium psychrophilum strains isolated from farmed Atlantic salmon ... more Characterization of 20 Flavobacterium psychrophilum strains isolated from farmed Atlantic salmon and rainbow trout in Chile was done using phenotypic, antigenic and genetic techniques. Experimental infections were also performed to assess the virulence of two representative isolates and of the type strain. Biochemical and physiological analyses showed that Chilean F. psychrophilum strains, regardless of the host species, constitute a phenotypically very homogeneous group matching with previous descriptions of this pathogen. However, serological assays indicated the existence of antigenic heterogeneity with four patterns of serological reactions. The first group contained most (14 of 20) of the F. psychrophilum isolates showing cross-reaction with the antisera obtained against Atlantic salmon and rainbow trout isolates. Group 2 corresponded to four other rainbow trout isolates (1658, 1731, 1762 and 29009) that did not agglutinate with anti-1150 serum. Two minor serological groups were identified for the remaining isolates (Groups 3 and 4). Marked homogeneity was also revealed by genetic studies including 16S rRNA alleles, random amplified polymorphic DNA and REP-PCR showing that a major genetic group of F. psychrophilum may be dominant in disease outbreaks in farms. Restriction fragment length polymorphism of PCR analysis showed that gyrase genotypes B-S or B-R were found in Chilean isolates from rainbow trout and Atlantic salmon, whereas genotype A was not found. Virulence assays using Atlantic salmon indicated no relationship between the degree of pathogenicity and the host origin of the F. psychrophilum strains.
Frontiers in Cellular and Infection Microbiology
Tenacibaculosis occurs due to the marine bacterial pathogen Tenacibaculum maritimum. This ulcerat... more Tenacibaculosis occurs due to the marine bacterial pathogen Tenacibaculum maritimum. This ulcerative disease causes high mortalities for various marine fish species worldwide. Several external clinical signs can arise, including mouth erosion, epidermal ulcers, fin necrosis, and tail rot. Research in the last 15 years has advanced knowledge on the traits and pathogenesis mechanisms of T. maritimum. Consequently, significant progress has been made in defining the complex host-pathogen relationship. Nevertheless, tenacibaculosis pathogenesis is not yet fully understood. Continued research is urgently needed, as demonstrated by recent reports on the re-emerging nature of tenacibaculosis in salmon farms globally. Current sanitary conditions compromise the development of effective alternatives to antibiotics, in addition to hindering potential preventive measures against tenacibaculosis. The present review compiles knowledge of T. maritimum reported after the 2006 review by Avendaño-Herr...
Nanopore sequencing evidenced the presence of fish bacterial pathogens in the sea louse (Caligus rogercresseyi) microbiota collected from distant salmon farms in Chile
Aquaculture, 2022
Identification and Characterization of the Iron Uptake System in Different Chilean Renibacterium Salmoninarum Isolates and Its Influence on Pathogenesis and Inmunogenicity in Atlantic Salmon and Rainbow Trout
Frontiers in Immunology, 2020
Bacterial Kidney Disease (BKD), which is caused by a Gram-positive, intracellular bacterial patho... more Bacterial Kidney Disease (BKD), which is caused by a Gram-positive, intracellular bacterial pathogen (Renibacterium salmoninarum), affects salmonids including Atlantic salmon (Salmo salar). However, the transcriptome response of Atlantic salmon to BKD remained unknown before the current study. We used a 44K salmonid microarray platform to characterise the global gene expression response of Atlantic salmon to BKD. Fish (∼54 g) were injected with a dose of R. salmoninarum (H-2 strain, 2 × 10 8 CFU per fish) or sterile medium (control), and then head kidney samples were collected at 13 days post-infection/injection (dpi). Firstly, infection levels of individuals were determined through quantifying the R. salmoninarum level by RNA-based TaqMan qPCR assays. Thereafter, based on the qPCR results for infection level, fish (n = 5) that showed no (control), higher (H-BKD), or lower (L-BKD) infection level at 13 dpi were subjected to microarray analyses. We identified 6,766 and 7,729 differentially expressed probes in the H-BKD and L-BKD groups, respectively. There were 357 probes responsive to the infection level (H-BKD vs. L-BKD). Several adaptive and innate immune processes were dysregulated in R. salmoninarum-infected Atlantic salmon. Adaptive immune pathways associated with lymphocyte differentiation and activation (e.g., lymphocyte chemotaxis, T-cell activation, and immunoglobulin secretion), as well as antigen-presenting cell functions, were shown to be differentially regulated in response to BKD. The infection level-responsive transcripts were related to several mechanisms such as the JAK-STAT signalling pathway, B-cell differentiation and interleukin-1 responses. Sixty-five microarray-identified transcripts were subjected to qPCR validation, and they showed the same fold-change direction as microarray results. The qPCRvalidated transcripts studied herein play putative roles in various immune processes including pathogen recognition (e.g., tlr5), antibacterial activity (e.g., hamp and camp), regulation of immune responses (e.g., tnfrsf11b and socs1), T-/B-cell differentiation (e.g., ccl4, irf1 and ccr5), T-cell functions (e.g., rnf144a, il13ra1b and tnfrsf6b), and Eslamloo et al. Atlantic Salmon Response to BKD antigen-presenting cell functions (e.g., fcgr1). The present study revealed diverse immune mechanisms dysregulated by R. salmoninarum in Atlantic salmon, and enhanced the current understanding of Atlantic salmon response to BKD. The identified biomarker genes can be used for future studies on improving the resistance of Atlantic salmon to BKD.
Aquaculture, 2019
In two recently published articles in Aquaculture, Mardones et al. (2018) discuss the emergent fi... more In two recently published articles in Aquaculture, Mardones et al. (2018) discuss the emergent fish pathogen and cause of salmonid rickettsial syndrome (SRS), Piscirickettsia salmonis, while Avendaño-Herrera (2018) discusses the heavy use of antimicrobials in Chile to prevent and treat salmonid bacterial infections including SRS. Mardones et al. put forward a research agenda that focuses largely on P. salmonis and its relation to the biology of SRS. We believe a broader view of the problem would be beneficial. An extended examination of the scientific literature suggests that P. salmonis is likely an opportunistic environmental pathogen with low levels of virulence and pathogenicity and/or an endogenous pathobiont colonizing the normal salmonid microbiome. Multiplication of this bacterium and its ability to produce SRS is at least in part triggered by shortcomings in piscine husbandry that negatively affect salmonid health and well-being. This explanation is consistent with the limited efficacy of vaccines and antimicrobials in preventing and modifying the course of SRS, and suggests that efforts focused on geographical concentration of aquaculture sites; high densities of cultured fish at these sites; levels of nutrients and eutrophication; co-infections with bacteria, viruses and sea lice; excessive use of antimicrobials and other treatments for these infections; and climate change would deserve increased research consideration in the future. In their analyses and proposed research agendas, neither of these articles takes into account the negative effects of excessive and perhaps unnecessary antimicrobial use on piscine, human and environmental health as understood by the One Health paradigm.
Brazilian Journal of Biology, 2009
FEMS Microbiology Letters, 2009
The 16S-23S rRNA intergenic spacer (ITS) of Vibrio anguillarum and Vibrio ordalii were PCR amplif... more The 16S-23S rRNA intergenic spacer (ITS) of Vibrio anguillarum and Vibrio ordalii were PCR amplified and cloned with TA vector pCR2.1. PCR amplification obtained five products ranging from 917 to 437 bp. Three clones were obtained and analysed from all fragments with the exception of 437 bp. These products were designated ITS-1, ITS-2, ITS-3 and ITS-4. ITS-1 contained genes for tRNA Glu(TTC) , tRNA Lys(TTT) , tRNA Ala(TGC) and tRNA Val(TAC) , while ITS-2 was almost the same as the ITS-1 sequence, but without tRNA Val(TAC). ITS-3 contained tRNA Ala(TGC) and tRNA Ile (GAT) and ITS-4, tRNA Ala (GGC) or tRNA Glu(TTC). The number of copies of the ribosomal operon (rrn) in V. ordalii chromosome ranged from at least six to seven and V. anguillarum had at least seven rrn. The sequences ITS-1, ITS-2 and ITS-3 showed a high similarity among the V. anguillarum and V. ordalii sequences (97.2% to 100%). Little variation was found for ITS-4, which does not seem to be sufficient to distinguish these two closely related species. Based on the findings, we confirm a close genetic relationship among V. anguillarum and V. ordalii and that they may be descended from a common ancestor in the Vibrionaceae linage.
Diseases of Aquatic Organisms, 2008
The sensitivity of 4 published primer pairs for the detection of Streptococcus phocae strains was... more The sensitivity of 4 published primer pairs for the detection of Streptococcus phocae strains was evaluated. Primer sets cpn60-F and-R and sodA-F and-R correctly identified S. phocae. Correct identification was also achieved with the primer pairs cae1-cae2 and PX1-PX2, but using the reverse complementary version of both reverse primers (caeVQ2 and PXVQ2, respectively). Among the 4 PCR protocols with pure and mixed cultures, the primer pair PX1-PXVQ2 provided the highest level of sensitivity for S. phocae (10 2 and 10 4 cells per PCR tube), and detection was 10-to 100-fold higher than the other 3 primer pairs. When the cae1-caeVQ2 and PX1-PXVQ2 PCR protocols were applied to different seeded Atlantic salmon tissues (spleen, kidney and liver), the detection limit achieved was 5.1 × 10 5 to 6.4 × 10 7 CFU g-1 , and the lowest sensitivity detected was 1.18 × 10 6 S. phocae per tube (which corresponds to 6.4 × 10 7 CFU g-1) in spleen samples using PX1-PXVQ2. In the kidney samples seeded with S. phocae strains, regardless of the primer set used, the PCR sensitivity was the same (7.31 ± 1.5 × 10 6 CFU g-1). In addition, the nested PCR assay using the primer pair PX1-PXVQ2 improved the sensitivity of detection of S. phocae by at least 100 times compared to the first round PCR, not only in mixed and pure suspensions, but also in experimentally seeded fish tissues. The picked tissues that allowed the easiest detection of S. phocae were the liver, kidney and spleen, respectively. Thus, the nested PCR approach is an important tool for the rapid and reliable diagnosis of streptococcosis due to S. phocae.
Optimization of settlement of larval Argopecten purpuratus using natural diatom biofilms
Journal of …, 2003
ABSTRACT
American Journal of Veterinary Research, 2007
Objective—To develop quantitative PCR (qPCR) assays with allele-specific primers to provide a rap... more Objective—To develop quantitative PCR (qPCR) assays with allele-specific primers to provide a rapid and accurate diagnostic and screening test for the 3 mutations identified as causes of gangliosidoses in domestic cats. Sample Population—DNA samples obtained from archived feline blood samples submitted for GM1 and GM2 testing. Procedures—A qPCR assay was developed for each mutation to monitor the efficiency of PCR amplification. Results were determined on the basis of the fluorescent intensity of DNA staining. Results—Samples from 60 cats were screened by use of the 3 qPCR assays. Of these, 59 qPCR results agreed with the sequence-derived genotypes. The phenotype (affected) for the other cat agreed with results for the qPCR assay, which indicated that interpretation of the sequence-based result was incorrect. Conclusions and Clinical Relevance—The qPCR assays offer a sensitive, rapid, and reproducible technique for allelic discrimination without the need for complicated processing s...
Vibriosis: <i>Vibrio anguillarum</i> , <i>V. ordalii</i> and <i>Aliivibrio salmonicida</i>
CABI eBooks, 2017
This chapter describes the epidemiology, prevalence, distribution, transmission, physiopathology,... more This chapter describes the epidemiology, prevalence, distribution, transmission, physiopathology, clinical signs, diagnosis, prevention, control strategies, legislative aspects and economic impact of Vibrio anguillarum, V. ordalii and Aliivibrio salmonicida in fishes.
Comparison between genome sequences of Chilean <i>Tenacibaculum dicentrarchi</i> isolated from red conger eel ( <i>Genypterus chilensis</i> ) and Atlantic salmon ( <i>Salmo salar</i> ) focusing on bacterial virulence determinants
Journal of Fish Diseases, Aug 9, 2021
Tenacibaculum dicentrarchi is an emerging pathogen for salmonid cultures and red conger eel (Geny... more Tenacibaculum dicentrarchi is an emerging pathogen for salmonid cultures and red conger eel (Genypterus chilensis) in Chile, causing high economic losses not only in Chile but also to the global salmon industry. Infected fish show severe gross skin lesions that are sometimes accompanied by bone exposure. Despite pathogenicity demonstrated by Koch's postulates, no knowledge is currently available regarding the virulence machinery of T. dicentrarchi strains. Comparisons between the genome sequences of the eight T. dicentrarchi strains obtained from G. chilensis and Atlantic salmon (Salmo salar) provide insights on the existence of genomic diversity within this bacterium. The T. dicentrarchi type strain 3509T was used as a reference genome. Depending on the T. dicentrarchi strain, the discovered diversity included genes associated with iron acquisition mechanisms, copper homeostasis encoding, resistance to tetracycline and fluoroquinolones, pathogenic genomic islands and phages. Interestingly, genes encoding the T9SS membrane protein PorP/SprF were retrieved in all of the analysed T. dicentrarchi strains, regardless of the host fish (i.e. red conger eel or Atlantic salmon). However, the T6SS core component protein VgrG was identified in only one Atlantic salmon strain. Three types of peptidase genes and proteins associated with quorum sensing were detected in all of the T. dicentrarchi strains. In turn, all eight strains presented a total of 17 proteins associated with biofilm formation, which was previously confirmed through physiological studies. This comparative analysis will help elucidate and describe the genes and pathways that are likely involved in the virulence process of T. dicentrarchi. All or part of these predicted genes could aid the pathogen during the infective process in fish, making further physiological research necessary for clarification.
Journal of Fish Diseases, Jan 9, 2018
Contiguous sampling of ice spanning key intervals of the deglaciation from the Greenland ice core... more Contiguous sampling of ice spanning key intervals of the deglaciation from the Greenland ice cores of NGRIP, GRIP and NEEM has revealed three new silicic cryptotephra deposits that are geochemically similar to the well-known Borrobol Tephra (BT). The BT is complex and confounded by the younger closely timed and compositionally similar Penifiler Tephra (PT). Two of the deposits found in the ice are in Greenland Interstadial 1e (GI-1e) and an older deposit is found in Greenland Stadial 2.1 (GS-2.1). Until now, the BT was confined to GI-1equivalent lacustrine sequences in the British Isles, Sweden and Germany, and our discovery in Greenland ice extends its distribution and geochemical composition. However, the two cryptotephras that fall within GI-1e ice cannot be separated on the basis of geochemistry and are dated to 14358 AE 177 a b2k and 14252 AE 173 a b2k, just 106 AE 3 years apart. The older deposit is consistent with BT age estimates derived from Scottish sites, while the younger deposit overlaps with both BT and PT age estimates. We suggest that either the BT in Northern European terrestrial sequences represents an amalgamation of tephra from both of the GI-1e events identified in the ice-cores or that it relates to just one of the ice-core events. A firm correlation cannot be established at present due to their strong geochemical similarities. The older tephra horizon, found within all three ice-cores and dated to 17326 AE 319 a b2k, can be correlated to a known layer within marine sediment cores from the North Iceland Shelf (ca. 17179-16754 cal a BP). Despite showing similarities to the BT, this deposit can be distinguished on the basis of lower CaO and TiO 2 and is a valuable new tie-point that could eventually be used in high-resolution marine records to compare the climate signals from the ocean and atmosphere.
Co‐existence of two <i>Yersinia ruckeri</i> biotypes and serotype O1a retrieved from rainbow trout ( <i>Oncorhynchus mykiss</i> ) farmed in Puno, Peru
Journal of Fish Diseases, Nov 20, 2022
Yersinia ruckeri causes important economic losses for rainbow trout (Oncorhynchus mykiss) farms w... more Yersinia ruckeri causes important economic losses for rainbow trout (Oncorhynchus mykiss) farms worldwide. This bacterial disease is likely the most common among trout in Peru; however, no commercial vaccine is available nationally, which is, in part, due to a lack of information on the bacterium. The aim of the current study was to characterize 29 Y. ruckeri isolates sampled from seven cage‐reared farms in the Puno Region, the focal point for aquaculture activities in Peru. For this, samples were taken from fish with clinical signs (i.e. haemorrhages, uni‐ or bilateral exophthalmia, hyphaemia and/or melanosis). Notable among our findings was the existence of both Y. ruckeri biotype 1 (9 isolates) and biotype 2 (20 isolates; negative for sorbitol and Tween 80). The isolates further differed in API profiles 5307100 (21 isolates), 1307100 (4 isolates), 1305100 (2 isolates), 1307120 (1 isolate) and 5305100 (1 isolate), with the main differences being in the tests for lysine decarboxylase, gelatine hydrolysis and D‐saccharose fermentation. Despite these differences, all isolates shared identical ERIC‐PCR and REP‐PCR profiles and belonged to the O1a serotype. Fingerprints were identical to the reference strain CECT 955 (serotype O1a). The information obtained will be used for epidemiological purposes by health authorities and for the development of a vaccine against Y. ruckeri, a prominent request made by fish farmers in Peru.
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Papers by Ruben Avendaño-Herrera