Infectious Pancreatic Necrosis Virus Isolates Research Articles

Traditional Chinese medicine bufalin inhibits infectious pancreatic necrosis virus genogroups I and V infection in vitro and in vivo

Infectious pancreatic necrosis virus (IPNV) is the causative pathogen of infectious pancreatic necrosis (IPN), which causes high mortality and great economic losses in salmon and trout aquaculture. IPNVs are divided into seven genotypes, and all IPNV isolates that have been reported in China belong to genogroups I and V. Because of restrictions on imported vaccines, China has no commercial vaccine against IPNV; Therefore, more effective antiviral drugs and vaccines are needed. Traditional Chinese medicine (TCM) has been used to treat endemic and pandemic diseases and is reported effective against viral infections. We screened a TCM library containing 1483 compounds and found that bufalin exhibited anti-IPNV activity. Bufalin inhibits infections from IPNV genogroups I and V by inhibiting viral internalization and RNA replication rather than viral attachment. In vivo results showed that bufalin significantly inhibited viral loads in IPNV-targeted tissues in rainbow trout. Mechanistic research showed that bufalin's antiviral effects occurred via Na+/K+-ATPase. Our results indicate that bufalin inhibits IPNV infections both in vitro and in vivo and may be a promising drug for treating IPNV infections.

Characterization of a Novel Infectious Pancreatic Necrosis Virus (IPNV) from Genogroup 6 Identified in Sea Trout (Salmo trutta) from Lake Vänern, Sweden.

In November 2016, infectious pancreatic necrosis virus (IPNV) was isolated from a broodstock female of landlocked sea trout (Salmo trutta) in Lake Vänern in Sweden. VP2 gene sequencing placed the IPNV isolate in genogroup 6, for which pathogenicity is largely unknown. Lake Vänern hosts landlocked sea trout and salmon populations that are endangered, and thus the introduction of new pathogens poses a major threat. In this study we characterized the novel isolate by conducting an infection trial on three salmonid species present in Lake Vänern, whole genome sequencing of the isolate, and prevalence studies in the wild sea trout and salmon in Lake Vänern. During the infection trial, the pathogenicity of the Swedish isolate was compared to that of a pathogenic genogroup 5 isolate. Dead or moribund fish were collected, pooled, and analyzed by cell culture to identify infected individuals. In the trial, the Swedish isolate was detected in fewer sample pools in all three species compared to the genogroup 5 isolate. In addition, the prevalence studies showed a low prevalence (0.2-0.5%) of the virus in the feral salmonids in Lake Vänern. Together the data suggest that the novel Swedish IPNV genogroup 6 isolate is only mildly pathogenic to salmonids.

An inactivated vaccine against infectious pancreatic necrosis virus in rainbow trout (Oncorhynchus mykiss)

Infectious pancreatic necrosis virus (IPNV), belonging to the genus Aquabirnavirus within the family Birnaviridae, causes huge economic loss to the global salmonid industry every year. Recently, outbreaks of disease caused by genogroup I IPNV were found in many rainbow trout (Oncorhynchus mykiss) farms worldwide. An inactivated vaccine was prepared using a genogroup I IPNV isolate with an optimized procedure as incubation with β-propanolactone (BPL) at the final concentration of 0.5% at room temperature for 48 h. The inactivated vaccine was used to immunize rainbow trout, and the protection efficiency was evaluated by viral loads determination, immune-related genes quantification, and neutralizing antibody tests. The viral loads in immunized rainbow trout were significantly decreased and the strongest antiviral effect was observed on 30 days post-immunization (d.p.i). The expression of innate immune-related genes IFN-1, and Mx-1 genes were significantly up-regulated on 3, 7, and 15 d.p.i (p < 0.05), and adaptive immune-related genes CD4, CD8, and IgM genes were significantly up-regulated on 15 and 30 d.p.i (p < 0.05). Neutralizing antibodies were firstly detected on 30 d.p.i and the highest titer was observed on 45 d.p.i, which began to decrease on 60 d.p.i, but was still significantly higher than that in negative control fish. The results indicated that the vaccine prepared in this study could stimulate the non-specific and specific immune response and provide significant immune protection to the vaccinated rainbow trout.

Determination of VP2 sequence-based virulence motifs and phylogenetic analysis of domestic Turkish IPNV ısolates.

Infectious pancreatic necrosis (IPN) is a highly contagious disease of young salmonid fish and is one of the most severe economic diseases in aquaculture. In Turkey, an increase in infectious pancreatic necrosis virus (IPNV) outbreaks in freshwater rainbow trout have been reported in recent years. This study aimed to analyze the VP2 gene from recent IPNV isolates from Turkey to determine whether there are epidemiological links between IPNV isolates from rainbow trout (Oncorhynchusmykiss; 62) and sea bass (Dicentrarchuslabrax; 1), wild turbot (Scophthalmusmaximus; 1) and the environment in order to investigate potential wild and farmed fish interactions. In this study, 62 Turkish IPNV isolates collected over 10years (2005-2014) from rainbow trout, sea bass and turbot were genotypically characterized. The phylogenetic analysis indicated that Turkish IPNV isolates are closely related to strains from Denmark, Iran and Spain and that all Turkish IPNV isolates belong to genogroup V, serotype A2 (Sp strain). Furthermore, low genetic diversity was found among the Turkish isolates (identity, 95.5%-100% nucleotides and 97.8%-100% amino acids). The result of the analysis of the amino acid residues found at positions 217, 221 and 247 (proline, threonine and alanine, respectively) could be associated with virulence.

Molecular Evolution of Infectious Pancreatic Necrosis Virus in China.

Passive virus surveillance was performed in twenty-nine salmon and trout farms from seven provinces and districts in China during the period 2017–2020. A total of 25 infectious pancreatic necrosis virus (IPNV) isolates were obtained, mainly from rainbow trout (Oncorhynchus mykiss). The molecular evolution of these Chinese IPNV isolates and the previously reported Chinese IPNV strains ChRtm213 and WZ2016 was analyzed, based on their VP2 gene coding region sequences (CDS). All 27 Chinese IPNV isolates clustered within genogroups I and V, with 24 of the IPNV isolates belonging to genogroup I (including ChRtm213 and WZ2016), and only three isolates clustering in genogroup V. The Chinese genogroup I IPNV isolates lacked diversity, composing six haplotypes with 41 polymorphic sites, and the identity of nucleotide and amino acid sequences among the entire VP2 gene CDS from these isolates was 97.44%–100% and 98.19%–100%, respectively. Divergence time analyses revealed that the Chinese genogroup I IPNV isolates likely diverged from Japanese IPNV isolates in 1985 (95% highest posterior density (HPD), 1965–1997), and diverged again in 2006 (95% HPD, 1996–2013) in China. Each of the three Chinese genogroup V IPNV isolates has a unique VP2 gene CDS, with a total of 21 polymorphic sites; the identity of nucleotide and amino acid sequences among all VP2 gene CDS from these isolates was 98.5%–99.5% and 98.6%–99.0%, respectively. The data demonstrate that genogroups I and V are more likely the currently prevalent Chinese IPNV genotypes.

Isolation of a New Infectious Pancreatic Necrosis Virus (IPNV) Variant from a Fish Farm in Scotland.

The aquatic virus, infectious pancreatic necrosis virus (IPNV), is known to infect various farmed fish, in particular salmonids, and is responsible for large economic losses in the aquaculture industry. Common practices to detect the virus include qPCR tests based on specific primers and serum neutralization tests for virus serotyping. Following the potential presence of IPNV viruses in a fish farm in Scotland containing vaccinated and IPNV-resistant fish, the common serotyping of the IPNV isolates was not made possible. This led us to determine the complete genome of the new IPNV isolates in order to investigate the cause of the serotyping discrepancy. Next-generation sequencing using the Illumina technology along with the sequence-independent single primer amplification (SISPA) approach was conducted to fully characterize the new Scottish isolates. With this approach, the full genome of two isolates, V1810–4 and V1810–6, was determined and analyzed. The potential origin of the virus isolates was investigated by phylogenetic analyses along with tridimensional and secondary protein structure analyses. These revealed the emergence of a new variant from one of the main virus serotypes, probably caused by the presence of selective pressure exerted by the vaccinated IPNV-resistant farmed fish.

Low Pathogenic Strain of Infectious Pancreatic Necrosis Virus (IPNV) Associated with Recent Outbreaks in Iranian Trout Farms.

Infectious pancreatic necrosis (IPN), first described as acute viral catarrhal enteritis, is a highly contagious disease with variable pathogenicity that has been linked to genetic variation in the viral VP2 gene encoding the capsid protein. In this study, the IPN virus (IPNV) is isolated from the moribund fish from five of fourteen Iranian trout farms from 2015 to 2017. The affected fish showed mortality rates ranging from 20% to 60%, with the main clinical signs of exophthalmia, darkened skin, and mild abdominal distension, as well as yellow mucoid fluid in the intestine. Histopathological examination of intestinal sections confirmed acute catarrhal enteritis in all samples. RT-PCR assay of the kidney tissue and cell culture (CHSE-214) samples consistently confirmed the presence of the virus. The phylogenetic analysis of the partial VP2 sequence revealed that the detected isolates belong to genogroup 5, and are closely related to the Sp serotype strains of European origin. Characterization of VP2 of all isolates revealed the P217T221 motif that previously was associated with avirulence or low virulence, while all IPNV-positive fish in this study were clinically affected with moderate mortality. The IPNV isolates from Iran are associated with two lineages that appear to have originated from Europe, possibly via imported eggs.

Susceptibility of rainbow trout to three different genogroups of infectious pancreatic necrosis virus.

Infectious pancreatic necrosis (IPN) is a globally distributed viral disease that is highly prevalent in rainbow trout Oncorhynchus mykiss farms in Finland. Seven genogroups (1-7) of infectious pancreatic necrosis virus (IPNV) exist, of which genogroup 5 (serotype Sp) is generally considered to be the most virulent in European salmonid farming. In Finland, 3 genogroups (2, 5 and 6) have been detected. Genogroup 2 is the most widespread and to date is the only genogroup associated with clinical disease in field observations. A bath challenge model infection trial was conducted to investigate the potential pathogenicity of the existing Finnish IPNV genogroups on IPNV-negative rainbow trout fry. Three Finnish IPNV isolates, a positive control (a Norwegian genogroup 5 isolate previously associated with high virulence in Atlantic salmon Salmo salar) and a negative control were used, and mortality was recorded daily for 8 wk. The Finnish IPNV genogroup 5 isolate caused the highest cumulative mortality, and the genogroup 2 isolate also caused elevated mortalities. The genogroup 6 isolate caused only low mortality, and the positive control treatment showed negligible mortality. Fish exposed to the Finnish genogroup 2 and 5 isolates had IPN-associated lesions, while no lesions were noted in the other treatment groups. These results indicate that Finnish IPNV genogroup 5 is potentially the most virulent IPNV genogroup for Finnish rainbow trout. Interestingly, the Norwegian IPNV genogroup 5 isolate caused only a subclinical IPN infection, providing further evidence for a host species-dependent, virus isolate-related difference in virulence in IPNV genogroup 5. The results also support the continuation of legislative disease control of IPNV genogroup 5 in Finnish inland waters.

The Infectious Pancreatic Necrosis Virus (IPNV) and its Virulence Determinants: What is Known and What Should be Known.

Infectious pancreatic necrosis (IPN) is a disease of great concern in aquaculture, mainly among salmonid farmers, since losses in salmonid fish—mostly very young rainbow trout (Salmo gairdnery) fry and Atlantic salmon (Salmo salar) post-smolt—frequently reach 80–90% of stocks. The virus causing the typical signs of the IPN disease in salmonids, named infectious pancreatic necrosis virus (IPNV), has also been isolated from other fish species either suffering related diseases (then named IPNV-like virus) or asymptomatic; the general term aquabirnavirus is used to encompass all these viruses. Aquabirnaviruses are non-enveloped, icosahedral bisegmented dsRNA viruses, whose genome codifies five viral proteins, three of which are structural, and one of them is an RNA-dependent RNA polymerase. Due to the great importance of the disease, there have been great efforts to find a way to predict the level of virulence of IPNV isolates. The viral genome and proteins have been the main focus of research. However, to date such a reliable magic marker has not been discovered. This review describes the processes followed for decades in the attempts to discover the viral determinants of virulence, and to help the reader understand how viral components can be involved in virulence modulation in vitro and in vivo. There is also a brief description of the disease, of host defenses, and of the molecular structure and function of the virus and its viral components.

Virulence of infectious pancreatic necrosis virus (IPNV) isolates from Mexico.

Infectious pancreatic necrosis virus (IPNV) causes economic losses in Mexican rainbow trout industry. In this study, virulence and genetic fingerprints of Mexican IPNV isolates was investigated for the first time. Two Mexican IPNV isolates were analyzed in rainbow trout fry and the Sp strain was included as high virulence. One of the Mexican IPNV isolate was obtained from diseased fish and the other from fish without clinical signs. The infection was performed using a standardized immersion. Clinical signs were observed at 4 days post infection in fry group infected with strain Sp, two days earlier than in trout infected with IPNV isolates Mexican. Severe lesions were found in 100% of the individuals of Sp group, but only in 25% of each isolated Mexican group. Results suggest that Mexican IPNV isolates are pathogenic, but less virulent than strain Sp. The amino acid motif residues of both Mexican isolates, corresponded to a subclinical disease. Nevertheless, the accumulated motility observed in the field, suggest that other factors play a role in the virulence of the disease.

Comparison of mortality and viral load in rainbow trout (Oncorhynchus mykiss) infected with infectious pancreatic necrosis virus (IPNV) genogroups 1 and 5.

Infectious pancreatic necrosis virus (IPNV) is the aetiological agent of a highly contagious disease that affects farmed salmonids. IPNV isolates have been phylogenetically classified into eight genogroups, of which two are present in Chile, genogroups 1 and 5. Here, we compare the mortality rate caused by isolates from both genogroups in rainbow trout (Oncorhynchus mykiss) fry to determine if there is an association between host susceptibility and phylogenetic characterization of IPNV. Fish were challenged by immersion with one of four isolates (two for each genogroup), and mortality curves were assessed after 30days. Viral load was measured in all mortalities and in live fish sampled at 1, 7 and 20days post-infection. Although mortality was low throughout the challenge, differences were found between fish infected with different isolates. Both isolates from genogroup 1 caused greater cumulative mortalities than either of the isolates from genogroup 5. When combined, the overall mortality rate of fish challenged with genogroup 1 isolates was significantly higher than those infected with genogroup 5. However, viral load was lower on trout infected with genogroup 1 isolates. These results suggest that rainbow trout are more susceptible to IPNV isolates from genogroup 1 than genogroup 5.

Molecular epidemiological study on Infectious Pancreatic Necrosis Virus isolates from aquafarms in Scotland over three decades.

In order to obtain an insight into genomic changes and associated evolution and adaptation of Infectious Pancreatic Necrosis Virus (IPNV), the complete coding genomes of 57 IPNV isolates collected from Scottish aquafarms from 1982 to 2014 were sequenced and analysed. Phylogenetic analysis of the sequenced IPNV strains showed separate clustering of genogroups I, II, III and V. IPNV isolates with genetic reassortment of segment A/B of genogroup III/II were determined. About 59 % of the IPNV isolates belonged to the persistent type and 32 % to the low-virulent type, and only one highly pathogenic strain (1.79 %) was identified. Codon adaptation index calculations indicated that the IPNV major capsid protein VP2 has adapted to its salmonid host. Under-representation of CpG dinucleotides in the IPNV genome to minimize detection by the innate immunity receptors, and observed positive selection in the virulence determination sites of VP2 embedded in the variable region of the main antigenic region, suggest an immune escape mechanism driving virulence evolution. The prevalence of mostly persistent genotypes, together with the assumption of adaptation and immune escape, indicates that IPNV is evolving with the host.

Molecular characterisation of infectious pancreatic necrosis viruses isolated from farmed fish in Finland

Infectious pancreatic necrosis virus (IPNV) has been isolated annually since 1987 from salmonids without clinical signs at coastal fish farms in Finland. In the inland area, viral isolations were rare until 2012, when IPNV was detected at several freshwater fish farms. Between 2013 and 2015, the infection spread and IPNV was continuously isolated from several farms, both inland and on the coast. The aim of this study was to genetically characterise the IPNV isolates collected from Finnish coastal and inland fish farms over the last 15 years, and to detect genetic changes that may have occurred in the virus populations during the study period. The partial VP2 gene sequence from 88 isolates was analysed. In addition, a complete genomic coding sequence was obtained from 11 isolates. Based on the genetic analyses, Finnish IPNV isolates belong to three genogroups: 2, 5 and 6. The genetic properties of the isolates appear to vary between inland farms producing juveniles and food fish farms in the coastal region: the inland farms harboured genogroup 2 isolates, whereas at coastal farms, all three genogroups were detected. Little genetic variation was observed within the Finnish genogroup 2 and 5 isolates, whereas among the genogroup 6 isolates, two subgroups were detected. All isolates studied demonstrated amino acid patterns in the viral VP2 gene previously associated with avirulence. However, increased mortality was detected at some of the farms, indicating that more research is needed to clarify the relationship between the pathogenicity and genetic properties of IPNV isolates from different genogroups.

Bivalent DNA vaccine induces significant immune responses against infectious hematopoietic necrosis virus and infectious pancreatic necrosis virus in rainbow trout

Infectious hematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV) are important pathogens of salmon and trout. An active bivalent DNA vaccine was constructed with the glycoprotein gene of Chinese IHNV isolate Sn1203 and VP2–VP3 gene of Chinese IPNV isolate ChRtm213. Rainbow trout (5 g) were vaccinated by intramuscular injection with 1.0 µg of the bivalent DNA vaccine and then challenged with an intraperitoneal injection of IHNV, IPNV, or both, at 30 and 60 days post-vaccination (d.p.v.). High protection rates against IHNV were observed, with 6% and 10% cumulative mortality, respectively, compared with 90–94% in the mock-vaccinated groups. IPNV loads (531-fold and 135-fold, respectively) were significantly reduced in the anterior kidneys of the vaccinated trout. Significant protection against co-infection with IHNV and IPNV was observed, with cumulative mortality rates of 6.67% and 3.33%, respectively, compared with 50.0% and 43.3%, respectively, in the mock-vaccinated groups. No detectable infective IHNV or IPNV was recovered from vaccinated trout co-infected with IHNV and IPNV. The bivalent DNA vaccine increased the expression of Mx-1 and IFN-γ at 4, 7, and 15 d.p.v, and IgM at 21 d.p.v., and induced high titres (≥160) of IHNV and IPNV neutralizing antibodies at 30 and 60 d.p.v.

Outbreak of infectious pancreatic necrosis virus (IPNV) in farmed rainbow trout in China

Infectious pancreatic necrosis virus (IPNV) is a member of the Aquabirnavirus genus, which caused mass mortality (nearly 100%) in farmed rainbow trout (Oncorhynchus mykiss) in aquaculture farms in 2016, China. Major clinical signs included decreased appetite, mucous-like stools, and darkened pigmentation. Pathological changes in moribund fish were observed, such as marked vacuolar degeneration of the pancreatic cells with pyknotic nucleus and decreased zymogen granules, severe hemorrhage in the liver, and tumidness of respiratory epithelium in gills. In addition, the tissue fluid of diseased fish could produce a cytopathic effect (CPE) in RTG-2 cells. The presence of specific 206bp fragments by the reverse transcription-polymerase chain reaction (RT-PCR) using tissue homogenate of diseased fish and supernatant of infected cells revealed that IPNV could be confirmed. The pathogenicity test of cell culture supernatant detected cumulative mortality of 80%, and the clinical symptoms observed in the moribund and dead fish were similar to the naturally infected fish. Furthermore, the sequence analysis of VP2 gene showed that the isolated virus strain belonged to genogroup 1, and 97% homology with the Mexican IPNV isolate was found. To our knowledge, this is the first report on IPNV natural infection in the southwest of China.

Molecular characterization of infectious pancreatic necrosis virus strains isolated from the three types of salmonids farmed in Chile

BackgroundThe infectious pancreatic necrosis virus (IPNV) causes significant economic losses in Chilean salmon farming. For effective sanitary management, the IPNV strains present in Chile need to be fully studied, characterized, and constantly updated at the molecular level.MethodsIn this study, 36 Chilean IPNV isolates collected over 6 years (2006–2011) from Salmo salar, Oncorhynchus mykiss, and Oncorhynchus kisutch were genotypically characterized. Salmonid samples were obtained from freshwater, estuary, and seawater sources from central, southern, and the extreme-south of Chile (35° to 53°S).ResultsSequence analysis of the VP2 gene classified 10 IPNV isolates as genogroup 1 and 26 as genogroup 5. Analyses indicated a preferential, but not obligate, relationship between genogroup 5 isolates and S. salar infection. Fifteen genogroup 5 and nine genogroup 1 isolates presented VP2 gene residues associated with high virulence (i.e. Thr, Ala, and Thr at positions 217, 221, and 247, respectively). Four genogroup 5 isolates presented an oddly long VP5 deduced amino acid sequence (29.6 kDa). Analysis of the VP2 amino acid motifs associated with clinical and subclinical infections identified the clinical fingerprint in only genogroup 5 isolates; in contrast, the genogroup 1 isolates presented sequences predominantly associated with the subclinical fingerprint. Predictive analysis of VP5 showed an absence of transmembrane domains and plasma membrane tropism signals. WebLogo analysis of the VP5 BH domains revealed high identities with the marine birnavirus Y-6 and Japanese IPNV strain E1-S. Sequence analysis for putative 25 kDa proteins, coded by the ORF between VP2 and VP4, exhibited three putative nuclear localization sequences and signals of mitochondrial tropism in two isolates.ConclusionsThis study provides important advances in updating the characterizations of IPNV strains present in Chile. The results from this study will help in identifying epidemiological links and generating specific biotechnological tools for controlling IPNV outbreaks in Chilean salmon farming.

Complete genomic sequence of an infectious pancreatic necrosis virus isolated from rainbow trout (Oncorhynchus mykiss) in China.

Infectious pancreatic necrosis (IPN) is a significant disease of farmed salmonids resulting in direct economic losses due to high mortality in China. However, no gene sequence of any Chinese infectious pancreatic necrosis virus (IPNV) isolates was available. In the study, moribund rainbow trout fry samples were collected during an outbreak of IPN in Yunnan province of southwest China in 2013. An IPNV was isolated and tentatively named ChRtm213. We determined the full genome sequence of the IPNV ChRtm213 and compared it with previously identified IPNV sequences worldwide. The sequences of different structural and non-structural protein genes were compared to those of other aquatic birnaviruses sequenced to date. The results indicated that the complete genome sequence of ChRtm213 strain contains a segment A (3099 nucleotides) coding a polyprotein VP2-VP4-VP3, and a segment B (2789 nucleotides) coding a RNA-dependent RNA polymerase VP1. The phylogenetic analyses showed that ChRtm213 strain fell within genogroup 1, serotype A9 (Jasper), having similarities of 96.3% (segment A) and 97.3% (segment B) with the IPNV strain AM98 from Japan. The results suggest that the Chinese IPNV isolate has relative closer relationship with Japanese IPNV strains. The sequence of ChRtm213 was the first gene sequence of IPNV isolates in China. This study provided a robust reference for diagnosis and/or control of IPNV prevalent in China.

Infectious pancreatic necrosis virus (IPNV) strain with genetic properties associated with low pathogenicity at Finnish fish farms.

Infectious pancreatic necrosis (IPN) is a contagious viral disease of fish that causes economic losses in aquaculture worldwide. In Finland, IPN virus (IPNV) has been isolated since 1987 from adult fish showing no signs of clinical disease at fish farms located in the coastal areas of the Baltic Sea. The inland area of Finland, however, remained free of IPN until 2012, when fish on several rainbow trout farms were diagnosed IPNV-positive. The fish mortalities detected at the farms were low, but clinical signs and histopathological changes typical for IPNV infection were seen in juvenile salmonids. IPNV was isolated at high water temperatures up to 22°C. In 2013 and 2014, IPNV detections continued at inland farms, indicating that infections have spread. The aim of this study was to describe the epidemiology of the outbreak and to characterise the Finnish inland IPNV isolates using histopathological, immunohistochemical and genetic approaches. In order to determine the epidemiological origin of the inland IPNV infections, the partial viral capsid protein (VP2) gene sequences of the inland IPNV isolates were compared with the sequences of the isolates from the coastal farms. Based on the genetic analysis, the inland isolates belong to IPNV Genogroup 2 (Serotype A3/Ab), and the origin of the isolates appears to be one or several coastal fish farms.

Chilean IPNV isolates: Robustness analysis of PCR detection

Background: The genomes of several infectious pancreatic necrosis virus (IPNV) isolated in Chile were sequenced, by using a single amplification approach for both segments A and B. The obtained sequences were used to investigate how conserved were the primer binding regions used in PCR-based diagnosis methods described in literature. The analysis allowed us to study the robustness of each technique, which could be affected in the eventual case of further mutations within the primer binding sites. Results: Analysis showed that most of the methods to detect Chilean IPNV varieties are currently adequate. However, the primers themselves were designed in function of specific genogroups, implying that most detection methods present some level of risk for detecting all strains present in the country, since genogroups 1 and 5 coexist. Conclusions: Considering IPNV high genomic variability, negative results must be taken with caution. The use of detection techniques (qRT-PCR) based on degenerate primers should be considered to minimize possibilities of false negative detections. Normal 0 21 false false false ES-CL X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-ansi-language:ES-CL; mso-fareast-language:EN-US;}

Characterization of an infectious pancreatic necrosis virus from rainbow trout fry (Onhorhynchus mykiss) in West Ukraine.

In this report, an aquatic birnavirus was isolated from rainbow trout fry, Onhorhynchus mykiss, during a fish health inspection in fish-farms in the west region of Ukraine near the rivers Siret and Cheremosh(Chernivtsi region). Preliminary examination of infected fish revealed a range of lesions, particularly in pancreatic tissue. Morphological changes, such as vacuole enlargement and cell rounding, were caused by viruses in appropriate cell lines. Investigation by electron microscopy demonstrated that the isolated virus was ultrastructurally similar to infectious pancreatic necrosis virus(IPNV). In addition, the nucleotide sequences of the 1120 bp VP2 gene fragments were analyzed and the identity of the isolated IPNV to strain Sp was revealed. The identity of nucleotide sequences was 97%–99%; the isolates of Sp strains most closely related to the Ukrainian IPNV isolate were found in Norway.