Virulence properties of three new Photobacterium species affecting cultured fish.

AIMS: Several virulence factors of three new Photobacterium species: Photobacterium toruni, Photobacterium malacitanum and Photobacterium andalusiense associated with diseases of cultured redbanded seabream (Pagrus auriga) were studied. The exoenzymatic activities, adherence and cytotoxic capabilities, and iron-uptake mechanisms were determined both in bacterial extracellular products (ECP) and whole bacterial cells. The histopathology damages provoked on redbanded seabream by the ECP was also studied. METHODS AND RESULTS: The highest exoenzymatic activities of the ECP were alkaline- and acid-phosphatase, phosphohydrolase and lipase. The ECP were strongly lethal for fish at 4-96 h post-inoculation (p.i). Histological changes were evident at 96 hpi of ECP, affecting head kidney, splenic parenchyma and heart. Cytotoxicity assays, on three fish lines and one human cell line, were conducted using whole bacterial cells and their ECP. The new species tested were cytotoxic only for fish cell lines using whole bacterial cells. Bacterial adherence showed an adherence index moderate on CHSE-214 cell line. All strains showed variable haemolytic activity, and were able to grow under iron-limiting conditions, although the CAS reactivitiy was very low. However, all strains produced high amounts of extracelullar citrate that could be used as iron carrier, and use haem as iron source, except the P. toruni strains because a deletion in the genomic region encoding this ability in all Vibrionaceae members. CONCLUSIONS: The toxic activity of the bacterial ECPs was thermolabile, and not associated with their thermoresistant lipopolysaccharide content. The virulence of the strains tested could not be related to the haemolytic activity. Iron uptake could be based on the use of endogenous citrate as iron carrier and P. toruni lacks the ability to use haem as iron source. SIGNIFICANCE AND IMPACT OF THE STUDY: The study analyses for the first time the virulence properties of three new species of Photobacterium pathogenic for fish.

Delimitation of the upstream region of NFKBIA gene associated with HTLV-1-associated myelopathy/tropical spastic paraparesis using candidate Tag-SNPs in Peruvian HTLV-1 infected individuals.

In Peru, it is estimated that about 150 000-400 000 people carry the Human T-lymphotropic virus 1 (HTLV-1). Only 10% of HTLV-1 carries develop complications related to HTLV-1. HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic disabling inflammatory disease affecting the spinal cord. HAM/TSP produces principally weakness in the lower limbs and bladder disturbances, among other complications. In a previous study, our group identified three SNPs (rs3138053, rs2233406, and rs3138045) located in the promoter region of the NFKBIA gene associated with HAM/TSP. This study aimed to analyze the association between four Tag-SNPs (rs10148482, rs17103274, rs17103282, and rs762009) located in the upstream region of the NFKBIA gene and HAM/TSP, and to delimit the linkage disequilibrium zone in the upstream region of the NFBKIA gene associated with HAM/TSP. The tetra-primers ARMS-PCR technique was used to genotype 4 Tag-SNPs on 140 HAM/TSP patients and 258 asymptomatic carriers. The SNP rs17103282 showed a deviation from Hardy-Weinberg equilibrium (p < .0001). Neither of three Tag-SNPs showed an association with HAM/TSP (P > .05). No linkage disequilibrium between four Tag-SNPs evaluated in this study and previous ones was observed. Here we show the region located in the upstream region of the NFKBIA gene highly associated with HAM/TSP disease in patients infected with HTLV-1 from Lima, Peru.