Detection of gill-associated virus (GAV) by in situ hybridization during acute and chronic infections of Penaeus monodon and P. esculentus.

Chronic and acute gill-associated virus (GAV) infections were examined by in situ hybridization (ISH) using a DNA probe targeting a 779 nucleotide region of the ORF1b-gene. Chronic GAV infections were observed in healthy Penaeus monodon collected from farms and healthy P. esculentus surviving experimental infection.

The complete genome sequence of gill-associated virus of Penaeus monodon prawns indicates a gene organisation unique among nidoviruses.

We report here a 5596 nt sequence comprising the 3'-end of the (+) ssRNA genome of gill-associated virus (GAV), an invertebrate nidovirus of Penaeus monodon prawns. The sequence extends from a subgenomic RNA start site 35 nt upstream of the 4923 nt ORF3 gene to a 3'-poly(A) tail of the 26235 nt genome of GAV. The putative 1640 amino acid (aa) ORF3 protein (MW = 182049 Da, pI = 6.

Vertical transmission of gill-associated virus (GAV) in the black tiger prawn Penaeus monodon.

Chronic gill-associated virus (GAV) infection is endemic in Penaeus monodon broodstock captured from north-east Queensland in Australia and in farmed shrimp produced from these. We investigated the role of vertical transmission in perpetuating the high prevalence of these chronic GAV infections. Reverse transcription (RT)-nested PCR detected GAV in spermatophores and mature ovarian tissue from broodstock and in fertilized eggs and nauplii spawned from wild-fertilized females.

Gill-associated nidovirus of Penaeus monodon prawns transcribes 3'-coterminal subgenomic mRNAs that do not possess 5'-leader sequences.

Sequence analysis of the approximately 20 kb 5'-terminal portion of the ssRNA genome of gill-associated virus (GAV) of Penaeus monodon prawns has previously established that it contains an ORF1a-1b replicase gene equivalent to those of the coronavirus and arterivirus members of the order Nidovirales. Sequence analysis of the remaining approximately 6.2 kb of the GAV genome downstream of ORF1a-1b to a 3'-poly(A) tail has identified two highly conserved intergenic sequences in which 29/32 nucleotides are conserved.

Antibody-antigen kinetics following immunization of rainbow trout (Oncorhynchus mykiss) with a T-cell dependent antigen.

Enhancement of the immune response through affinity maturation of the antibody response is a feature of the mammalian immune system and has important implications with respect to development of vaccination strategies. However, an absence of germinal centres and apparent lack of somatic hypermutation of immunoglobulin V genes suggests that this phenomenon does not occur in fish. We investigated the question of affinity maturation in rainbow trout (Oncorhynchus mykiss) by measuring antibody-antigen binding kinetics using a BIAcore biosensor.

Detection of Australian gill-associated virus (GAV) and lymphoid organ virus (LOV) of Penaeus monodon by RT-nested PCR.

A highly sensitive test based on reverse transcription followed by nested polymerase chain reaction (RT-nPCR) was developed to detect the Australian yellow-head-like viruses, gill-associated virus (GAV) and lymphoid organ virus (LOV) of Penaeus monodon. The RT-nPCR detected viral RNA in as little as 10 fg lymphoid organ total RNA isolated from GAV-infected P. monodon.

Further studies on acquired resistance to amoebic gill disease (AGD) in Atlantic salmon, Salmo salar L.

Trials were designed to test the efficacy of freshwater treatments for amoebic gill disease (AGD) of Atlantic salmon, Salmo salar L., and the effect they had on the acquisition of resistance to reinfection with AGD. The first trial involved fish being given an industry-simulated freshwater bath of 2-3 h duration which simulated treatments given on farms.