Protection of rainbow trout from infectious hematopoietic necrosis (IHN) by injection of infectious pancreatic necrosis virus (IPNV) or Poly(I:C)

Abstract

It was recently reported that prophylaxis against infectious hematopoietic necrosis virus (IHNV) in fish was induced by pre-exposure to the infectious pancreatic necrosis virus (IPNV). Here the establishment of IHNV immunity in rainbow trout Oncorhynchus mykiss was investigated by IHNV challenge following non-lethal pre-infection with IPNV. Also, synthetic double-stranded RNA polyinosinic polycytidylic acid, Poly(I:C), an inducer for interferon (IFN), was evaluated as a substitute for IPNV induction of the non-specific antiviral state and subsequent IHNV-specific immunity in fish. Rainbow trout pre-infected with IPNV were protected from IHNV challenge 7 d later (relative percentage survival, RPS: 68.8%), and IHNV-specific antibodies were detected in sera from the survivors. Moreover, these surviving fish showed 91.6% RPS when re-challenged with IHNV 28 d after the primary IHNV challenge. Thus, fish appear to acquire IHNV-specific immunity through the IHNV challenge following pre-injection with IPNV. Fish pre-injected with Poly(I:C) were also highly protected from IHNV challenge 2 d later (RPS: 95.2%), and IHNV-specific antibodies were also detected amongst survivors. The survivors showed a 100% survival rate following re-challenge with IHNV both 21 and 49 d after the primary IHNV challenge. Thus, IHNV immunity in rainbow trout is induced by challenge with live IHNV following pre-injection with either IPNV or Poly(I:C). The use of Poly(I:C) to induce an anti-viral state protecting rainbow trout from an otherwise lethal vaccination dose of IHNV may have application to a wider range of fish species and fish pathogenic viruses. KEY WORDS: Immunization · Infectious hematopoietic necrosis virus · IHNV · Poly(I:C) · Interferon · Antiviral state · Dual infection · Vaccine Resale or republication not permitted without written consent of the publisherDis Aquat Org 83: [105][106][107][108][109][110][111][112][113] 2009 be more pathogenic in juveniles. The evolutionary divergence of IHNV influences its pathogenicity, but this has not been elucidated scientifically (Nishizawa et al. 2006a).In seed production facilities for salmonids, stable production of specific-pathogen-free (SPF) fish has been accomplished by measures for the prevention of IHNV transmission, such as disinfection of eggs with iodine, and sterilization of rearing water and facilities. Furthermore, maintenance of SPF-spawners monitored by antibody detection (ELISA) is also important and helpful to prevent vertical transmission of IHNV (Yoshimizu 1996(Yoshimizu , 2003. However, it is still difficult to prevent horizontal transmission of IHNV through water flow in rainbow trout farms. Therefore, development of an IHNV vaccine is essential, and several kinds of efficacious IHNV vaccines have been developed, e.g. killed or attenuated vaccines (Winton 1997, Biering et al. 2005, recombinant vaccines with IHNV G protein (Xu et al. 1991, Cain et al. 1999) and DNA vaccines with IHNV G gene (Anderson et al. 1996, Kim et al. 2000, Lorenzen et al. 2002.Prot...

Viral fitness does not correlate with three genotype displacement events involving infectious hematopoietic necrosis virus

“…For IHNV infection in rainbow trout, it has been thoroughly documented that, within the first few days of infection, the host response is dominated by a strong induction of numerous interferon-stimulated genes, including Mx-1 [22]. In addition, pre-treatment of rainbow trout with injection of Poly(I:C), a TLR-3 agonist, offers significant protection from infection and mortality following challenge with IHNV [23]. For displacement pair 1, Mx-1 expression in fish exposed to genotype 007 was significantly higher than that in fish exposed to genotype 111 at day four post-infection, but not on any other day.…”

Cell Culture Medium Inhibits Antigen Binding Used in an ELISA for Detection of Antibodies against Nervous Necrosis Virus

“…Several studies using ELISA systems for the detection of specific fish antibodies have been reported for aquatic animals (Jorgensen et al 1991;Yoshimizu et al 1992;Dixon et al 1994;Pilström 1994, 1995;LaPatra 1996;Nishida et al 1998;Watanabe et al 1998;Swain and Nayak 2003;Okuda et al 2006;Kim et al 2007Kim et al , 2008Kim et al , 2009Takami et al 2010). However, use of an ELISA for fish antibody detection can be problematic because of difficulties such as low reproducibility, which is partly due to high background optical density (OD) caused by nonspecific reactions between fish antibodies and antigens Pilström 1994, 1995;Knopf et al 2000;Kibenge et al 2002;Guo and Woo 2004).…”

The Role of Virulence in In Vivo Superinfection Fitness of the Vertebrate RNA Virus Infectious Hematopoietic Necrosis Virus

“…The time between primary and secondary virus challenge was not a controlled factor in this study; therefore, conclusions could not be made about the importance of time between infections on viral replication in superinfection. In addition to these, many studies have investigated the effect of concurrent multiple infection with viruses of different species in natural and model hosts (4,29,31,(33)(34)(35). Thus, the dynamics of in vivo superinfection with variants of the same viral species have yet to be extensively defined for a vertebrate RNA virus and may provide insight into the mechanisms behind many of the field observations of superinfection for other important vertebrate viruses.…”