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Abalones (Haliotis spp.) are economically important seafoods. However, the appearance of lethal diseases since 1999, such as those caused by low-temperature viruses, have led to the near collapse of the aquaculture industry of small abalone (H. diversicolor) in southern China. The abalone herpesvirus (AbHV) is one of these suspected low-temperature viral pathogens, but the absence of epidemic data of AbHV in abalone species in China has hampered in-depth studies of AbHV and the identification of the pathogen(s) causing abalone viral disease(s). Here, we performed the first epidemiological study on AbHV in China, using quantitative PCR. The first batch of abalone individuals (n = 1082) was collected monthly from April 2012 to October 2013 at seven sites along the coast of the South China Sea. Analyses revealed the presence of AbHV in cultured abalone in China, with a detection rate of 27.73%. Most individuals were healthy and showed a viral DNA load below 103 copies per ng host DNA. No effect of the culture method (artificial pond culture or open sea raft culture), shell length, or host species (H. diversicolor and H. discus hannai) on the viral load was detected. In the second batch of samples (n = 500), collected between 2002 and 2012, AbHV was detected at a detection rate of 29.20%. Ultra-high viral DNA loads (105 to 107 copies/ng host DNA) were detected in the diseased abalone samples. Artificial infection results confirmed the pathogenicity of AbHV to H. diversicolor, suggesting that AbHV is probably the pathogen responsible for the abalone low-temperature viral disease. These findings will benefit the abalone aquaculture industry, as it provides data that can be used to improve the control of viral diseases, and facilitate further AbHV-related studies.

Accumulating data has demonstrated that ferritin plays an important role in host defense responses against infection by pathogens in many organisms. In this study, ultracentrifugation was used to isolate ferritin from abalone, Haliotis diversicolor, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed that this ferritin consisted of two subunits (designated as HdFer1 and HdFer2). There are no disulfide bonds between the HdFer1 and HdFer2 subunits; however, these subunits co-assemble to form heteropolymers. A novel ferritin subunit (HdFer2) was cloned from H. diversicolor by 5' and 3' RACE (rapid amplification of cDNA ends) approach. The full-length HdFer2 cDNA sequence consists of 878 bp with an open reading frame of 513 bp that encodes a protein that is 170 amino acids in length. Quantitative real-time PCR analysis revealed that HdFer1 and HdFer2 were transcribed in various tissues, such as the mantle, gill and hepatopancreas, with the highest levels of expression in the hepatopancreas. Following a challenge with the pathogen, Vibrio harveyi, the expression of HdFer1 and HdFer2 were markedly induced at different times. This study has identified a novel ferritin subunit in H. diversicolor which will contribute to further exploration of the role of ferritin in mollusk innate immune defense against invading pathogens.

Leuprolide acetate, a potent agonist of luteinizing hormone-releasing hormone (LHRH), was found to display little or no secondary structure in aqueous solution as determined by circular dichroism (CD) spectroscopy. However, upon addition of trifluoroethanol, CD spectra consistent with type II β-turn structures were observed. CD spectroscopy was also employed to evaluate the aggregation of leuprolide in solution. In aqueous solution, leuprolide does not readily aggregate. However, in ethanol/water mixtures, concentration- and temperature-dependent aggregation was observed. This demonstrates that CD spectroscopy can be an effective analytical tool for assessing not only the structure of peptides, but also detecting peptide aggregation.