Cumulative Percent Mortality Research Articles

Vaccination against Furunculosis in Arctic Char: Efficacy of a Commercial Vaccine.

Arctic char Salvelinus alpinus are susceptible to furunculosis, a serious bacterial disease that affects the productivity of salmonid farms around the world. The objective of this laboratory study was to evaluate the efficacy of a commercially available vaccine against furunculosis in two strains of Arctic char. Labrador and Nauyuk char were injected with Aqua Health Furogen 2 or 0.9% NaCl. At 87 and 108 d postvaccination, fish were challenged with Aeromonas salmonicida by immersion. In both challenges, the Aqua Health vaccine provided significant protection against furunculosis; percent cumulative mortality was significantly (P = 0.005) greater for the fish vaccinated with 0.9% NaCl than for those vaccinated with Furogen 2. Strain (P = 0.30), days since vaccination (P = 0.38), and the interaction between vaccine and strain (P = 0.40) were not significant. The point estimate for the preventive fraction (PF) was greater than 0.90 for the Labrador fish vaccinated with Furogen 2; for the Nauyuk fish, the PF was 0.89 and 0.38 at 87 and 108 d, respectively. Relative proportion survival values were also estimated and were usually similar to, but always lower than, the PF estimates.

Pathogens and insects in a pristine forest ecosystem: the Sierra San Pedro Martir, Baja, Mexico

We determined the incidence of pathogens and insects across mixed-conifer stands in the Sierra San Pedro Martir (SSPM) of northern Baja, Mexico, to assess the role of pests in a pristine forest ecosystem. We also determined the spatial distribution of the two most common pests, mistletoe, Phoradendron pauciflorum Torrey, and the fir engraver, Scolytus ventralis LeConte, of white fir (Abies concolor (Gord. & Glend.) Lindl.) across a 25-ha grid to assess spread and what host and pest variables were related. In these open parklike stands the mean tree density was 160 trees/ha, of which 58% were trees >20 cm diameter at breast height (DBH). In these low-density, mixed-aged stands we found that mixed-conifer species were well represented with no one species being completely dominant. Percent cumulative mortality for the SSPM was 12.7%, ranging from 2 to 24%, with the greatest amount of mortality occurring in the larger size classes, trees [Formula: see text]50 cm DBH. Multiple linear regression analysis showed that 78% of the mortality we observed was explained by pathogens and bark beetles (r2 = 0.78, P = 0.0001, F = 84). Mean pest incidence for Jeffrey pine (Pinus jeffreyi Grev. & Balf. in A. Murray), white fir, and sugar pine (Pinus lambertiana Dougl.) was 21, 88, and 2%, respectively. We found a number of relationships among host and pest variables, as well as a pathogen– insect interaction, and across the SSPM we found that nonhost species may be interfering in certain host–pest interactions. Spatial patterns from the 25-ha grid survey revealed that both P. pauciflorum and S. ventralis incidence were widespread. Phoradendron pauciflorum showed no spatial structure across the 25 ha but S. ventralis showed some degree of spatial structuring across the survey area. We also found that mistletoe severity was negatively correlated with regeneration of white fir. In pristine forests, pathogens and insects influence mortality and regeneration success, affecting stand structure and composition.

Increased Susceptibility of Juvenile Chinook Salmon to Vibriosis after Exposure to Chlorinated and Aromatic Compounds Found in Contaminated Urban Estuaries

Abstract Saltwater-adapted juvenile chinook salmon Oncorhynchus tshawytscha exposed to aromatic and chlorinated compounds, representative of contaminants found in urban estuaries in Puget Sound, have a higher susceptibility to vibriosis than do fish exposed only to the solvent vehicle. Susceptibility to vibriosis was assessed by examining the percent cumulative mortality of the salmon after exposure to the bacterial pathogen Vibrio anguillarum. The aromatic and chlorinated compounds examined consisted of a sediment extract from the Hylebos Waterway that was enriched in butadienelike compounds (chlorinated-enriched Hylebos Waterway sediment extract (CHWSE)), a model mixture of polycyclic aromatic hydrocarbons (PAHs), a polychlorinated biphenyl mixture (Aroclor 1254), hexachlorobutadiene (HCBD), and 7,12-dimethylbenz(a)anthracene (DMBA). Two trials were conducted. In trial l, the percent cumulative mortality of juvenile chinook salmon exposed to V. anguillarum after receiving either CHWSE, HCBD, or the mode...

Post-spacing mortality of lodgepole pine from armillaria root disease

To evaluate the threat of armillaria root disease in precommercially thinned lodgepole pine (Pinus contorta var. latifolia), a total of 66 15 × 15-m plots were established in dense lodgepole pine regeneration, 18 to 21 years after harvest, on three infested sites near Hinton, Alberta. Three treatments (2.5-m spacing, 1.5-m spacing and an unspaced control) were randomly applied to plots having similar densities and levels of mortality. After 11 years there was no significant difference among the treatments in cumulative percent mortality. Based on observed levels of mortality, it would appear that spacing need not be avoided in infested stands, although it likely would be prudent to space more closely than 2.5 m in younger stands and in parts of stands having more than 5–10% mortality. Key words: precommercial thinning, spacing, armillaria root disease, Armillaria ostoyae

Increased susceptibility of juvenile chinook salmon to infectious disease after exposure to chlorinated and aromatic compounds found in contaminated urban estuaries

Saltwater-adapted juvenile chinook salmon ( Oncorhynchus tshawytscha) exposed in the laboratory to various aromatic and chlorinated hydrocarbons representative of those found in urban estuaries in Puget Sound have a higher susceptibility to infectious disease relative to carrier-exposed juveniles. Disease susceptibility was assessed by examining the temporal percent cumulative mortality in juvenile chinook salmon after exposure to the marine pathogen, Vibrio anguillarum. Aromatic and chlorinated compounds tested included a sediment extract from the Hylebos Waterway predominantly composed of butadiene-like compounds (CHWSE), a model mixture of polycyclic aromatic hydrocarbons (PAHs), hexachlorobutadiene (HCBD), a PCB mixture (Aroclor 1254), and a single PAH, dimethylbenz[a]anthracene (DMBA). The effect of these compounds on disease susceptibility was tested in two separate trials. In Trial I, the percent cumulative mortality in salmon exposed to bacteria after exposure to either CHWSE, HCBD, or the model mixture of PAHs ranged from 28 to 31%, as compared to 16% in the acetone:emulphor control group at 7 days after challenge. In Trial II, the cumulative mortality in salmon ranged from 46 to 49% after exposure to either DMBA or the PCB mixture compared to 25% in the acetone:emulphor control group at 9 days after challenge. These results suggest that juvenile chinook salmon migrating to the ocean through a contaminated estuary experience immunodysfunction, characterized by lowered resistance to disease, which potentially could affect survival of populations that are particularly threatened.

Use of Hydrogen Peroxide to Treat Experimentally Induced Bacterial Gill Disease in Rainbow Trout

Bacterial gill disease, experimentally produced in rainbow trout Oncorhynchus mykiss exposed to Flavobacterium branchiophilum, was effectively treated by using 1-h static baths containing hydrogen peroxide as an alternative to treatment with chloramine-T. The optimal concentration of hydrogen peroxide depended on the number of treatments, the time intervals between them, and the stage of the disease. When administered as two treatments at 48-h intervals, 250 mg hydrogen peroxide/L was more effective than 10 mg chloramine-T/L. The effectiveness of 100 mg hydrogen peroxide/L was more variable, but treatment consistently and significantly reduced percent cumulative mortality (PCM) compared with untreated control groups; treatment with 25 mg/L was less effective. Clearance of gill-associated F. branchiophilum antigen was greatest with chloramine-T or 250 mg hydrogen peroxide/L; 100 mg hydrogen peroxide/L was again more variable. Three 1-h static baths at 24-h intervals reduced the concentration of hydrogen peroxide required for effective treatment. Whereas replicate groups treated with chloramine-T at 10 mg/L had the lowest PCM, those treated with concentrations of hydrogen peroxide as low as 25 mg/L also had very low PCM. Although levels of gill-associated F. branchiophilum antigen were lowest in those groups treated with hydrogen peroxide at 125 and 175 mg/L, higher PCM occurred with increasing concentrations of hydrogen peroxide. Chloramine-T treatment, however, resulted in low levels of gill-associated F. branchiophilum antigen as well as low PCM. Treatment of healthy and F. branchiophilum-infected groups of fish with a single 1-h exposure to 300 or 450 mg hydrogen peroxide/L did not cause any deaths in the week following exposure.

Screen Barriers To Repel Slugs From Foraging On To Greenhouse Benches, Hawaii, 1995

Abstract Screen Barriers To Repel Slugs From Foraging On To Greenhouse Benches, Hawaii, 1995 Efficacy studies were conducted from 2 Oct through 20 Dec at the University of Hawaii at Manoa, Waiakea Agricultural Research Station in Hilo, Hawaii. Greenhouse bench legs were simulated by placing a 6 X 8 X 16 inch concrete hollow tile block vertically (common bench leg used in Hawaii) in the center of a 1.5 X 2 ft plastic arena. A 1 -inch thick layer of moistened pest covered the bottom of the arena; and a 1-inch barrier of NaCl on the perimeter of the arena prevented slugs from escaping. The test screen (1.0 ft2) rested on the bench end of the block. Treatments included: 0.011 gauge, 16 mesh copper screen; 0.011 gauge, 18X16 mesh aluminum screen; 18X16 mesh fiberglass screen and a 12 X 12 X 0.13 inch paper board control. A 7.75-inch dia saucer containing moist-ened Slug and Snail AG Pelleted Bait (Hacco Inc., Madison, WI) was placed on the screen barrier as an attractant and to evaluate efficacy (slugs crossing the barrier would feed and die). One hundred field collected slugs were placed in each arena. Tests were conducted in a dark ventilated room and replicated three times with 100 slugs per replicate for both species. Efficacy was determined daily by counting the number of dead slugs in the saucer. The cumulative percentage mortality over 7 days was recorded.

Strain differences in non-specific immunity of tilapia Oreochromis niloticus following challenge with Vibrio parahaemolyticus

DAO Diseases of Aquatic Organisms Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials DAO 30:77-80 (1997) - doi:10.3354/dao030077 Strain differences in non-specific immunity of tilapia Oreochromis niloticus following challenge with Vibrio parahaemolyticus Balfry SK, Shariff M, Iwama GK Red and black strains of tilapia Oreochromis niloticus were compared for differences in non-specific immunity. Communally reared, naive fish were challenged with the bacterium Vibrio parahaemolyticus. Serum lysozyme, phagocyte activity and differential leucocyte numbers were examined in pre-challenge and post-challenge fish. The percent cumulative mortality in the 2 strains were not significantly different. There was a significant effect of strain on serum lysozyme activity and phagocyte activity. Phagocyte activity increased significantly following the disease challenge. Lymphocyte numbers decreased significantly in the post-challenge sample, while thrombocytes, neutrophils, and monocytes remained unchanged. This study provides the first report of strain differences in non-specific immunity in tilapia. Tilapia · Disease resistance · Non-specific immunity · Vibrio parahaemolyticus · Lysozyme · Phagocytic activity · Leucocyte counts Full text in pdf format PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in DAO Vol. 30, No. 1. Publication date: July 24, 1997 Print ISSN:0177-5103; Online ISSN:1616-1580 Copyright © 1997 Inter-Research.

The relationships between hydrodynamics, the concentration of hydrogen sulphide produced by polluted sediments and fish health at several marine cage farms in Scotland and Ireland

Waste products from marine cage salmon farming can cause organic enrichment of the benthos in the immediate area of the farm with potentially deleterious consequences to fish health. The relationships between benthic enrichment and hydro-dynamic parameters - mean current speed, maximum current speed and incidence of low currents - were examined. Benthic impact was assessed on the basis of SCUBA diver observation and measurements of hydrogen sulphide in the water immediately (within 30 cm) overlying the sediment at slack water. Other factors such as maximum site biomass and the age of the site were also considered. At 7 of the 8 salmon farms studied there was a good correlation between mean current speed (r=−0.877) and incidence of low currents (r= 0.943) with log mean hydrogen sulphide concentration. The lack of correlation for the remaining site was thought to be due to a combination of high levels of terrigenous organic input to the site and overfeeding. The relationship between fish growth and mortality with hydrogen sulphide concentration was also examined. Good correlation between both fish growth (r=−0.819) and cumulative percentage mortality (r= 0.941), and log mean hydrogen sulphide concentration were found when the data from one exceptional site were excluded.

The effect of early exposure of Coho salmon ( Oncorhynchus kisutch) eggs to the p57 protein of Renibacterium salmoninarumon the development of immunity to the pathogen

Bacterial kidney disease (BKD) in salmonids is caused by Renibacterium salmoninarum(Rs) which is transmitted vertically through salmonid eggs. This study investigated the effect of vertical transmission of one protein of Rs, p57, on the development of the immune system of coho salmon ( Oncorhynchus kisutch) and on the susceptibility of the fish to subsequent challenge with Rs. It was shown that exposure of coho salmon at the egg stage to the p57 protein of Rs induces at least partial immunosuppression. Coho salmon eggs were injected with varying amounts of p57. The eggs were fertilized, the progeny were vaccinated against Rs, and then challenged with live, virulent Rs. Fish that had been injected as eggs with 100 ng of p57 demonstrated a significantly higher cumulative percent mortality (50 %) than those from the saline-injected eggs (controls) (14 %). The same fish also produced significantly lower levels of antibodies against p57, although not against whole Rs cells, than those derived from saline-injected eggs. It appeared, therefore, that there was some specificity to the immune suppression. A decreased proportion of phagocytic cells isolated from fish exposed as eggs to 100 ng p57, showed respiratory burst activity (0 ·4 %) compared with the proportion of cells isolated from the saline-injected (control) group (16 ·5 %). These data suggest that early (egg stage) exposure of coho salmon to p57 results in long-term immunosuppression and a decreased ability in the animal to resist subsequent challenges with Rs.

Acute effects of chlorinated resin acid exposure on juvenile rainbow trout,Oncorhynchus mykiss

AbstractThe effects of an acute exposure to either 14–monochlorodehydroabietic acid (MCDHAA) or 12,14–dichlorodehydro‐abietic acid (DCDHAA) were examined in juvenile rainbow trout,Oncorhynchus mykiss.The experimentally determined 96–h LC50 values (and their 95% confidence limits) were 1.03 (0.72, 1.48) and 0.91 (0.70, 1.21) mg/L, for MCDHAA and DCDHAA, respectively. To measure effects on several biochemical parameters, swimming performance, and disease resistance, juvenile trout were exposed for 24 h to sublethal concentrations of one or the other resin acid in an intermittent‐flow respirometer. Hematocrit, plasma lactate, and liver protein were significantly affected by exposure to the highest dose (80% of the 96‐h LC50 value) of either of the resin acids. Plasma cortisol levels were 14‐and 3‐fold higher than were controls. Resistance to infection byAeromonas salmonicidawas significantly reduced; the cumulative percent mortalities due to furunculosis in fish exposed to MCDHAA or DCDHAA reached 20 and 26%, respectively. Swimming performance, measured as critical swimming speed (mean values 6.32 ± 0.20 and 5.93 ± 0.15 body lengths per second for MCDHAA and DCDHAA, respectively), was not significantly affected by resin acid exposure.

Production of gill-associated and serum antibody byrainbow trout ( Oncorhynchus mykiss) following immersion immunization with acetone-killed Flavobacterium branchiophilum and the relationship to protection from experimental challenge

Rainbow trout ( Oncorhynchus mykiss) were either injected twice intraperitoneallywith 0·1 ml of a 1:10 dilution from broth culture of acetone-killed Flavobacterium branchiophilum, immersed twice for 1 h in a 1:10, 1:100 or 1:1000 dilution from a broth culture of acetone-killed F. branchiophilum, or utilized as unexposed controls. After bath challenge with live F. branchiophilum the percent cumulative mortality of each group was as follows; controls, 45·3%, i.p.-injected, 32·1%; immersed in a 1:1000 dilution, 38·0%; immersion in a 1:100, 40·9%; and immersion in a 1:10 dilution, 11·7%. There was no relationship between the group treatment and the levels of F. branchiophilum antigen detected by enzyme immunoassay following challenge. The amount of gill-associated and serum antibody to F. branchiophilum detected in the immersion immunized groups before challenge increased with increasing concentration of antigen in the bath. The i.p.-injected group had the highest serum antibody of any group while gill-associated antibody was comparable to those groups which were bath exposed with the lower concentrations of F. branchiophilum antigen. A similar pattern of antibody response was seen with five groups of rainbow trout treated exactly as the five groups above, in which antibody was monitored over time, but which were not challenged. Gill-associated and serum antibody were detectable following primary antigen exposure regardless of route. The serum and gill-associated antibody responses were present for longer following a second antigen exposure by the same route, and the gill-associated but not the serum antibody was increased over those following primary antigen exposure. The greatest increase in gill-associated antibody response was seen in the group which received the highest concentration of antigen via bath.

Protection of Rainbow Trout from Experimentally Induced Bacterial Gill Disease Caused byFlavobacterium branchiophilum

Rainbow trout Oncorhynchus mykiss from the same genetic pool and varying in size from 10 to 400 g (a) were challenged with broth cultures of Flavobacterium branchiophilum and the survivors were held for approximately 2 months, (b) were injected intravenously with rainbow trout anti-F. branchiophilum or rainbow trout anti-sheep red blood cell hyperimmune serum, (c) were vaccinated by bath or the intraperitoneal route two or three times with acetone-killed F. branchiophilum, or (d) were used as unprotected challenge controls. These groups of fish were then challenged with various doses of broth cultures of F. branchiophilum. Those challenged with large doses (8 × 1010 colony-forming units, cfu) of bacteria displayed mortality rates similar to that of unprotected controls. As the challenge dose decreased (from 2 × 1010 to 2 × 109 cfu), the cumulative percent mortality of controls decreased. The cumulative percent mortality of groups that had been previously exposed to live F. branchiophilum, had received F. branchiophilum-specific serum intravenously, or had been bath-vaccinated declined to a proportionately greater extent than unprotected controls. Fish that were bath-vaccinated three times were almost completely protected from experimental challenge. A quantitative enzyme immunoassay for F. branchiophilum antigen revealed significantly (P < 0.05) decreased antigen loads on the gills of fish that had been vaccinated-compared with loads on untreated fish-only during the first 3 d following challenge. No significant (P > 0.05) differences in antigen load were seen in fish that had been previously exposed nor in those that had received intravenous rainbow trout anti-F. branchiophilum antiserum.

Efficacy of Sarafloxacin Hydrochloride in Treating Naturally-InducedEdwardsiella ictaluriInfections in Channel Catfish,Ictalurus punctatus

Sarafin (sarafloxacin hydrochloride), a new antibacterial, was evaluated in the field on a naturally induced infection of Edwardsiella ictaluri in channel catfish, -Ictalurus punctatus. Healthy channel catfish (mean weight = 50 g) were stocked into nine cages at 200 fish per cage in a pond with an undergoing E. ictaluri infection. Seven days after stocking, dead fish were observed in the cages with clinical signs of enteric septicemia of channel catfish (ESC). After E. ictaluri was confirmed through isolative biochemical tests, medicated feed was applied for five consecutive days. During this period, fish in three control cages received a commercial 32% protein floating feed, three other cages of fish served as positive controls and were fed Romet, and three cages received the test feed with Sarafin. Both medicated feeds reduced the increase in cumulative percent mortality. In the control cages, cumulative percent mortalities continued to increase throughout the study period. Average daily mortality rates...

Laboratory Evaluation of Steinernematid Nematodes Against Grasshoppers, 1992

Abstract Laboratory tests were conducted to determine the effectiveness of a commercial preparation of steinernematid nematodes, BioSafe, on 5 species of grasshoppers. The nematode suspension was prepared according to label directions. Clipped barley (2 wk old) was spread out on toweling and sprayed with the nematode suspension. Three microscope slides were placed on the toweling at regular intervals to determine the concentration of nematodes sprayed. A small hand sprayer was used for application. The number of nematodes was counted in each of 5 randomly selected microscope fields on each slide. The concentration of nematodes sprayed averaged 2.9 ± 0.34 per mm2. After spraying, the barley was divided equally and placed in clear plastic containers (10 cm diam, 6 cm high) with screened tops. Twelve adult grasshoppers of each species were placed in each container. The test was replicated twice. As a check, untreated barley was placed in one container for each species. The containers were checked daily for 20 d and dead grasshoppers were removed and stored at 4°C for later dissection. Cumulative percent mortality was calculated for each container. Dead grasshoppers were dissected to confirm the presence of nematodes in grasshoppers from treated containers.

Impact of Transesophageal Echocardiography on the Treatment of Patients with Aortic Dissection

To determine the impact of transesophageal echocardiography (TE) on the treatment of patients with aortic dissection, the clinical course and outcome of 18 patients with TE diagnosis of dissection were analyzed. Ascending aortic dissection was present in nine patients, of whom six had surgery with confirmation of TE findings. Angiography was performed in only two of these patients and was falsely negative in one patient. Angiography was not performed in the three patients who were not surgical candidates. In the nine patients who had descending aortic dissection, angiography was performed in seven patients, of whom two underwent surgery. Information provided by angiography did not change the treatment of these patients. Thus, TE provides a prompt and accurate diagnosis in aortic dissection obviating the need for angiography in most patients.

Subacute toxicity of Fenthion to New Zealand white rabbits (Orcyctalagus cunticulus)

The subacute toxicity of the insecticide f enthion was studied using New Zealand White Rabbits as test animals. Toxicity was noted within 24 hours in animals dosed at levels as low as 3% of the LD50 value with mortality occurring 20 days following daily feeding of this lowest dose. Cumulative percent mortality was a function of both dose and exposure tine. The LD50 values resulting from daily feeding of the fenthion at 5, 10 and 20 mg kg‐1 were 30, 12 and 9 mg kg‐1, for 5, 10 and 15 day respectively.

Effects of temperature and dosage on Vairimorpha sp. 696 spore morphometrics, spore yield, and tissue specificity in Heliothis virescens

The effects of temperature and dosage on a new microsporidian species, Vairimorpha sp. 696, were examined in H. virescens. The pathogen was evaluated for tissue specificity, spore size, cumulative percentage mortality, and spore production. All tissues examined bore infection at 32°C. Spore length was significantly longer at 19°C (5.9 μm) than at 32°C (4.7 μm). Spore widths at these two temperatures did not differ significantly. Octospores were not found at either temperature at 8 or 12 days postinoculation. One hundred percent mortality was attained in all dosages administered, but the initial rate of mortaily was more rapid in the higher dosages. Finally, spore yield was greater in larvae administered lower dosages. Maximum spore yield at 27°C was 4.87 × 10 9 spores/larva.

Prevention of clindamycin-induced mortality in hamsters by Saccharomyces boulardii.

Saccharomyces boulardii, a yeast used in a number of countries for general and antibiotic-associated gastrointestinal illnesses, was examined for possible application in the prevention of clindamycin-induced mortality in the hamster colitis model. Hamsters were given free access to an aqueous 5% suspension of lyophilized yeast for 3 days before and 10 days after administration of a single oral clindamycin dose of from 0.2 to 0.8 mg/kg. Mortality was recorded in groups of 7 to 20 animals every 24 h for 10 to 30 days. Mean cecal concentrations of S. boulardii were greater than 10(6) CFU/ml throughout the yeast administration period. Yeast treatment significantly decreased cumulative percent mortality by an average of 29%. Death onset was not affected by yeast treatment. Cecitis was present in 86% of moribund animals (N = 95) and was absent in all surviving animals examined (N = 27). Toxigenic Clostridium difficile was isolated from 13 of 14 moribund hamsters examined. No adverse effects of the yeast treatment were observed in animals receiving S. boulardii without clindamycin. The results suggest that S. boulardii warrants further evaluation for the prevention of antibiotic-associated colitis.

Influence of diabetes mellitus heredity on susceptibility to coxsackievirus B4.

Using the criteria of virus susceptibility as defined by the 50 percent lethal dose response and the percent cumulative mortality response it was shown that the diabetic mutation db, located on chromosome 4, exerted a particular influence on the host response to CB4 challenge. Neither the yellow obese mutation Ay on chromosome 2 nor the misty coat color mutation located one centimorgan from the db mutation had the same effect on CB4 response. The obese diabetic mutation ob located on chromosome 6 appeared to enhance susceptibility to CB4. However, the high susceptibility of the inbred C57BL/6J line on which the ob mutation is found was apparently a significant contributing factor to the ob mutant high virus susceptibility. The response to CB4 was also a useful criteria to discern differences in the genetic background of closely related inbred lines. Based on the CB4 LD50 values the C57BL/6J inbred line was the most susceptible while the C57BL/Ks inbred line was the most resistant. However, using the percent cumulative mortality response as an index of host resistance, the C57BL/KsJ was the most susceptible and the C57BL/Ks the least. These findings further support the thesis that genetic predisposition to diabetes mellitus, as characterized by the mutation db on chromosome 4 is associated with a particular susceptibility and host response to coxsackie-virus B4. It also illustrates that under specific conditions, comparison of the response to virus challenge can be used as an indicator of genetic differences between closely related inbred lines.