Ammocoetes of Pacific Lamprey are not susceptible to common fish rhabdoviruses of the U.S. Pacific northwest.

Pacific Lampreys Entosphenus tridentatus have experienced severe population declines in recent years and efforts to develop captive rearing programs are under consideration. However, there is limited knowledge of their life history, ecology, and potential to harbor or transmit pathogens that may cause infectious disease. As a measure of the possible risks associated with introducing wild lampreys into existing fish culture facilities, larval lampreys (ammocoetes) were tested for susceptibility to infection and mortality caused by experimental exposures to the fish rhabdovirus pathogens: infectious hematopoietic necrosis virus (IHNV) and viral haemorrhagic septicaemia virus (VHSV). Two IHNV isolates, representing the U and M genogroups, and one VHSV isolate from the IVa genotype were each delivered to groups of ammocoetes by immersion at moderate and high viral doses, and by intraperitoneal injection. Ammocoetes were then held in triplicate tanks with no substrate or sediment. During 41 d of observation postchallenge there was low or no mortality in all groups, and no virus was detected in the small number of fish that died. Ammocoetes sampled for incidence of infection at 6 and 12 d after immersion challenges also had no detectable virus, and no virus was detected in surviving fish from any group. A small number of ammocoetes sampled 6 d after the injection challenge had detectable virus, but at levels below the original quantity of virus injected. Overall there was no evidence of infection, replication, or persistence of any of the viruses in any of the treatment groups. Our results suggest that Pacific Lampreys are highly unlikely to serve as hosts that maintain or transmit these viruses.

Immunoglobulin and circulating immune complex kinetics during immunoadsorption onto protein A sepharose.

Immunoadsorption onto protein A sepharose can be applied to eliminate immunoglobulins, autoantibodies and circulating immune complexes from the circulation. In vivo kinetic studies showed that all IgG subclasses are removed from the patient's plasma although IgG3 elimination is variable and dependent on the presence of other immunoglobulins. IgG elimination half time was 4.8 days during intermittent and 2.9 days for daily therapy in the absence of immunosuppression. Autoantibodies and immune complexes can be cleared effectively but administration of intravenous immunoglobulins should be avoided because of competition for protein A binding sites. Redistribution/ denovo synthesis (half time 2.1-8.8 d for IgG 1-4) occurred in the absence of immunosuppression.

A phylogenetic comparison of the 16S rRNA sequence of the fish pathogen, Renibacterium salmoninarum, to gram-positive bacteria.

The 16S rRNA of Renibacterium salmoninarum, the causative agent of bacterial kidney disease in salmonids, was sequenced by reverse transcriptase to produce a nearly complete sequence (97%) of 1475 nucleotides. Phylogenetic comparisons to seventeen genera and signature sequence analysis indicated that R. salmoninarum was a member of the high G + C Gram-positive eubacterial subdivision although the reported G + C value is only 53%. A phylogenetic tree details the relationship of R. salmoninarum to ten actinomycetes from diverse environments.

Sympathoadrenal and adrenal hormonal responses of newborn calves to hypothermia.

Seventeen newborn Holstein-Friesian bull calves were cold-stressed by total body immersion in water at 15 to 17 degrees C until the core body temperature was lowered by 10 degrees C. Nine additional calves (noncold-stressed) were immersed in water at 35 to 37 degrees C. Eight of the cold-stressed calves were euthanatized soon after removal from the water while the others (n=9) were allowed to recover in a cold room at 4 degrees C for 72 hours. Noncold-stressed calves were kept at 25 degrees C for 72 hours. Sympathoadrenal an adrenal hormonal responses of calves were determined by analysis of plasma for glucose, corticosteroids, and catecholamines. Plasma concentration of glucose and corticosteroids rapidly increased in cold-stressed calves soon after immersion and remained higher (P less than of equal to 0.05) than concentrations in noncold-stressed calves during immersion and most of recovery. There was a threefold increase (P less than or equal to 0.05) in concentration of catecholamines in plasma of cold-stressed calves and only a slight increase in noncold-stressed calves during immersion. Catecholamine concentrations remained elevated in cold-stressed calves during most of recovery. Results provide direct evidence that sympathoadrenal and adrenal hormonal responses to cold are well developed in newborn calves and that changes in concentrations of glucose, corticosteroids, and catecholamines in plasma of these animals are sensitive indicators of their ability to respond to cold stress.