Modulary effects of temperature on antibody response and specific resistance to challenge of channel catfish, Ictalurus punctatus, immunized against Edwardsiella ictaluri

The effects of various temperature treatments on the level of the humoral antibody response in channel catfish immunized with formalin killed Edwardsiella ictaluri was determined in laboratory controlled experiments. Immunized fish that were held at 25 degrees C for 30 days and 12 degrees C for an additional 30 days had higher antibody titers, and were more protected upon challenge, than immunized fish held at 25 degrees C for 60 days. Also immunized catfish held at 25 degrees C for 5 or 10 days followed by 12 degrees C water had higher antibody titers than immunized fish held at 12 degrees C or 25 degrees C for 60 days. In a field experiment carried out during winter and spring (February-May) fingerling channel catfish were vaccinated with E. ictaluri using intraperitoneal injection or immersion with either sonicated or whole cell preparations. Following challenge, the fish vaccinated by immersion in the sonicated preparation had 11.8% mortality whereas the groups immersed in whole cell bacterin, injected with the whole cell bacterin in adjuvant, or injected with sonicate showed 24.6, 57.9 and 41.7% mortality, respectively. Although the fish vaccinated by immersion with the sonicated bacteria had lower antibody titers than those vaccinated by the other methods the immersion vaccinates were more protected against challenge with the pathogen.     

Enhanced susceptibility of channel catfish to the bacterium Edwardsiella ictaluri after parasitism by Ichthyophthirius multifiliis

Bacterium Edwardsiella ictaluri and parasite Ichthyophthirius multifiliis (Ich) are two common pathogens of cultured fish. The objective of this study was to evaluate the susceptibility of channel catfish Ictalurus punctatus to E. ictaluri and determine bacterial loads in different fish organs after parasitism by Ich. Fish received the following treatments: (1) infected by I. multifiliis at 5000 theronts/fish and exposed to E. ictaluri; (2) infected by I. multifiliis alone; (3) exposed to E. ictaluri alone; and (4) non-infected control. E. ictaluri in fish organs were quantified by quantitative real-time polymerase chain reaction and reported as genome equivalents per mg of tissue (GEs/mg). The results demonstrated that the Ich-parasitized catfish showed significantly (P<0.05) higher mortality (91.7%) when exposed to E. ictaluri than non-parasitized fish (10%). The bacterial loads in fish infected by 5000 theronts/fish ranged from 6497 to 163,898 GEs/mg which was between 40 and 2000 fold higher than non-parasitized fish (49-141 GEs/mg). Ich infection enhanced the susceptibility of channel catfish to bacterial invasion and increased fish mortality.     

Effects of variable periods of food deprivation on the development of enteric septicemia in channel catfish

Enteric septicemia of catfish (ESC), caused by the bacterium Edwardsiella ictaluri, is the most significant bacterial disease affecting channel catfish Ictalurus punctatus. Withholding feed during outbreaks of ESC is a widely accepted industry practice used to control losses from the disease. Scientific evidence concerning the validity of the practice is contradictory. Two studies were conducted to further evaluate the survival of channel catfish fingerlings following variable periods of feed deprivation before and after exposure to E. ictaluri in controlled aquarium experiments. In the first study, feed was withheld for varying time periods before bacterial challenge. After bacterial challenge, feed was either withheld or fish were fed daily. The second study utilized fish fed daily or fish deprived of feed 7 d before bacterial challenge. Daily feeding was resumed 4, 48, and 96 h after fish were exposed to E. ictaluri. In both experiments, the prechallenge feed treatments did not affect mortality. In contrast, withholding feed after bacterial challenge reduced mortalities by 52% in experiment 1 and by 45% in experiment 2. The highest mortality was observed when fish were fed immediately after immersion exposure and the lowest when fish were completely denied feed or fed daily starting 96 h after challenge. This reduction in mortality occurred when the concentration of E. ictaluri in aquarium water was negligible. These data suggest that when E. ictaluri is present in the water, feeding fish increases mortality by enhancing oral exposure to the pathogen.     

Spleen index and mannose-binding lectin levels in four channel catfish families exhibiting different susceptibilities to Flavobacterium columnare and Edwardsiella ictaluri

Edwardsiella ictaluri and Flavobacterium columnare are two bacterial pathogens that affect channel catfish Ictalurus punctatus aquaculture. At the Catfish Genetics Research Unit (U.S. Department of Agriculture, Agricultural Research Service), some progress has been made in selectively breeding for resistance to E. ictaluri; however, the susceptibility of these families to F. columnare is not known. Our objectives were to obtain baseline information on the susceptibility of channel catfish families (maintained as part of the selective breeding program) to E. ictaluri and F. columnare and to determine whether the spleen index and plasma levels of mannose-binding lectin (MBL) are predictive indicators of susceptibility to these pathogens. Four channel catfish families were used: family A was randomly chosen from spawns of fish that were not selectively bred for resistance; families B, C, and D were obtained after selection for resistance to E. ictaluri. All four families were immersion challenged with both bacterial pathogens; the spleen index and plasma MBL levels of unchallenged fish from each family were determined. Mean cumulative percent mortality (CPM) after E. ictaluri challenge ranged from 4% to 33% among families. Families A and B were more susceptible to F. columnare (mean CPM of three independent challenges = 95% and 93%) than families C and D (45% and 48%), demonstrating that there is genetic variation in resistance to F. columnare. Spleen index values and MBL levels were not significantly different, indicating that these metrics are not predictive indicators of F. columnare or E. ictaluri susceptibility in the four tested families. Interestingly, the two families that exhibited the highest CPM after F. columnare challenges had the lowest CPM after E. ictaluri challenge. Further research on larger numbers of families is needed to determine whether there is any genetic correlation between resistance to E. ictaluri and resistance to F. columnare.     

Specific serum antibody responses in channel catfish (Ictalurus punctatus) provide limited protection against Streptococcus ictaluri challenge

Passive immunization studies were conducted to determine the role of specific antibodies in immunity to Streptococcus ictaluri. Adult channel catfish (Ictalurus punctatus) were injected i.p. with tryptic soy broth as control or with 1.5 × 10(7)colony-forming units (cfu) S. ictaluri/fish at 0, 30, and 60 d, and serum was collected 90 d after the original challenge. Fish were passively immunized by i.p. injection with serum from the tryptic soy broth (TSB) control group, anti-S. ictaluri serum from fish immunized three times and sampled at 90 d (SSI), or heat-inactivated anti-S. ictaluri serum from fish immunized three times and sampled at 90 d (HISSI). These passively immunized fish were then challenged 72 h later with 1.5 × 10(8)cfu S. ictaluri/fish. Over 21 d, the mean cumulative percent survival was 43.3 (TSB), 63.3 (SSI), and 50.0 (HISSI). A significant difference in cumulative percent survival was noted between the TSB and the HISSI groups, and significant differences were noted between these groups and the SSI group. Serum obtained from immunized fish 72 h after passive immunization exhibited increased anti-S. ictaluri antibody levels. Twenty-one days after the challenge, the HISSI and SSI group antibody levels significantly increased above their corresponding pre-challenge levels. No significant (r(2)=0.0806; P<0.5985) correlation between increased pre-challenge specific serum antibody levels and survival after challenge was demonstrated when analyzing the control and passive immunization groups. The results indicate that both specific anti-S. ictaluri antibodies and non-specific immune responses are important for protection against S. ictaluri.     

In vitro evaluation of the susceptibility of Edwardsiella ictaluri, etiological agent of enteric septicemia in channel catfish, Ictalurus punctatus (Rafinesque), to florfenicol.

In vitro studies were conducted to assess the sensitivity of Edwardsiella ictaluri, the etiological agent of enteric septicemia of catfish (ESC), to the antibacterial drug florfenicol (FFC). Twelve different E. ictaluri isolates from cases submitted between 1994 and 1997 to the Thad Cochran National Warmwater Aquaculture Center fish diagnostic laboratory (Stoneville, MS) were used for testing. These isolates originated from channel catfish (Ictalurus punctatus) infected with E. ictaluri through natural outbreaks of ESC in the commercial catfish ponds in Mississippi. Seven hundred sixty-seven additional cultures of E. ictaluri were obtained from channel catfish infected experimentally with E. ictaluri. In some of these experimental infections, FFC was used for treatment. These cultures of E. ictaluri were identified by morphological and biochemical tests. Kirby-Bauer zones of inhibition (in mm) for FFC against E. ictaluri were determined using standard methods. The minimum inhibitory concentration (MIC) of FFC was determined for the natural outbreak E. ictaluri isolates and arbitrarily selected experimental cultures. The zones of inhibition for FFC tested with E. ictaluri ranged from 31 to 51 mm. The MIC for FFC tested with E. ictaluri was consistently 0.25 microg/ml. Edwardsiella ictaluri tested in these studies were highly sensitive to FFC in vitro.     

Outer membrane protein profiles of Edwardsiella ictaluri from fish.

Outer membrane proteins (OMP) prepared with sodium N-lauroyl sarcocinate (SLS) from 33 Edwardsiella ictaluri isolates from fish were examined by electrophoresis. Twenty-eight isolates from channel catfish (Ictalurus punctatus) had similar OMP profiles. Ten bands (71 kilodaltons [kD] to 19.5 kD) were identified in all isolates from channel catfish. One major 35-kD protein comprised most of the protein content of the outer membrane of isolates from channel catfish. Differences existed among isolates in the amount of protein within minor OMP bands. Edwardsiella ictaluri ATCC 33202 contained larger quantities of the 38.5- and 37-kD proteins than did the other isolates. Outer membrane protein profiles of E ictaluri derived from Bengal danio (Danio devario) and walking catfish (Clarias batrachus) were identical to OMP profiles of isolates from channel catfish. In contrast, OMP profiles from single isolates from green knife fish (Eigemannia virescens) and white catfish (Ictalurus catus) were different. Variations in incubation time, SLS extraction time, SLS extraction number, and in vivo and in vitro passage had no effect on the OMP profile of E ictaluri ATCC 33202. An increase in duration of sample solubilization did affect the OMP profile of E ictaluri ATCC 33202 by decreasing the amount of protein in 52-, 46-, and 43.5-kD bands. Accompanying the decrease were increased staining intensity in the 31.5- and 28.5-kD bands and the appearance of 4 new bands (34, 33, 25.5, and 22.5 kD). Edwardsiella ictaluri, a gram-negative bacterium in the family Enterobacteriaceae, is the cause of enteric septicemia of catfish.(ABSTRACT TRUNCATED AT 250 WORDS)     

Identification and expression profile of multiple genes in Nile tilapia in response to formalin killed Streptococcus iniae vaccination

Twenty-eight expressed sequence tags (ESTs) were isolated from a Nile tilapia (Oreochromis niloticus) vaccinated vs non-vaccinated subtractive library at 12-h post injection of a formalin killed Streptococcus iniae ARS-98-60 vaccine. The 28 ESTs were classified in terms of their putative functions. Half of the ESTs identified were unknown proteins. Of the remaining half ESTs, 17% have putative functions in protein biosynthesis and 11% have putative functions in immunity, energy production, and signal transduction, respectively. Immunity-related ESTs identified included high density lipoprotein-binding protein vigilin, immunoglobulin heavy chain, and QM-like protein. Quantitative PCR revealed that one EST (cytochrome c oxidase subunit II) was highly upregulated (1825 ± 336 fold) in vaccinated fish compared to that in non-vaccinated fish. Of the remaining 27 ESTs, nine were significantly (P<0.05) upregulated (<20 fold) in vaccinated fish. The nine significantly upregulated genes included five unknown or hypothetical proteins and four known proteins (high density lipoprotein-binding protein vigilin, QM-like protein, ribosomal protein S13, and ribosomal protein L5). The upregulation of these genes induced by killed S. iniae vaccines suggest that they might play important role in Nile tilapia defense against S. iniae infection.     

Evaluation of zebrafish Danio rerio as a model for enteric septicemia of catfish (ESC)

Zebrafish (also known as zebra danio) Danio rerio were injected intramuscularly with Edwardsiella ictaluri at doses of 6 x 10(3), 6 x 10(4), or 6 x 10(5) colony-forming units per gram (CFU/g) or sterile phosphate-buffered saline (sham) or were not injected. Mortality occurred from 2 to 5 d postinjection (dpi) at rates of 0, 76.6, and 81.3% for the low, medium, and high doses, respectively, and E. ictaluri was isolated from dead fish. Survivors were sampled at 10 dpi and E. ictaluri was not isolated. Sham-injected and noninjected controls did not suffer mortality. Histopathology trials were performed in which zebrafish were injected with 1 x 10(4) CFU/g or sham-injected and sampled at 12, 24, 48, 72, and 96 h postinjection for histological interpretation. Collectively, these zebrafish demonstrated increasing severity of splenic, hepatic, cardiac, and renal interstitial necrosis over time. To evaluate the progression of chronic infection, zebrafish were injected with 1 x 10(2) CFU/g and held for 1 month postinjection. Beginning at 12 dpi and continuing for an additional 2 weeks, zebrafish demonstrated abnormal spiraling and circling swimming behaviors. Histopathology demonstrated necrotizing encephalitis. In immersion trials, zebrafish were exposed to low, medium, and high doses (averaging 1.16 x 10(5), 1.16 x 10(6), and 1.16 x 10(7) CFU/mL of tank water) of E. ictaluri for 2 h. Mortality occurred from 5 to 9 d postexposure at rates of 0, 3.3, and 13.3% for the low, medium, and high doses, respectively; E. ictaluri was isolated from dead fish. Channel catfish Ictalurus punctatus exposed to the medium doses suffered 100% mortality, and E. ictaluri was isolated from these fish. This study demonstrates the potential use of zebrafish as a model for E. ictaluri pathogenesis.     

Early interactions of Edwardsiella ictaluri, with Pangasianodon catfish and its invasive ability in cell lines

Commercial Pangasianodon catfish production is heavily impacted by Bacillary Necrosis of Pangasius (BNP) caused by Edwardsiella ictaluri. This study aimed to investigate the early bacterium-host interactions following immersion challenge and to compare the retrieved data with the invasion ability of the used isolates in fish cell lines. Firstly, Pangasianodon hypophthalmus fingerlings were challenged via immersion using E. ictaluri isolate HO2 or 223. At different times post inoculation, fish were sacrificed and gill and internal organ samples were taken for bacteriological, histological and immunohistochemical evaluation. The bacterial load was higher for fish inoculated with isolate HO2 compared with 223. Histological and immunohistochemical analysis revealed multifocal necrotic areas in kidney, spleen and liver of HO2 inoculated fish at 72 h post inoculation with short rod-shaped immunoperoxidase positive bacteria clustered inside cells respectively. Bacteria especially were present in the gills and intestinal tract of HO2 inoculated fish, suggesting the gastrointestinal tract and gills act as portals of entry. Following, the ability of HO2, 223 and four additional isolates to invade a Chinook salmon embryo cell line, a fat head minnow cell line and a rainbow trout liver cell line was tested. All E. ictaluri isolates were invasive in all cell lines albeit at different degrees. Isolate HO2 was highly invasive in all cell lines with a significantly higher invasion capacity than isolate 223 in the Chinook salmon embryo cell line. A correlation between in vivo virulence and in vitro invasiveness hence is suggested although further studies are needed to confirm this hypothesis.     

新肝宝对鲶爱德华氏菌感染黄颡鱼的保护作用研究

为了考察新肝宝对鲶爱德华氏菌感染黄颡鱼的保护作用,采用不同粉碎粒度的新肝宝拌饲投喂7 d,随后用鲶爱德华氏菌腹腔注射感染,观察死亡率、酶学指标及组织病理变化。结果显示,新肝宝组死亡率(48.57%和44.28%)低于阴性对照组(54.29%),溶菌酶及超氧化物歧化酶活性显著高于对照组(P<0.05),肝脏、肾脏、脾脏损伤情况均小于阴性对照组,其中600目作用效果优于200目。结果表明,新肝宝能够提高黄颡鱼非特异性免疫力,增强黄颡鱼对鲶爱德华氏菌的抵抗能力,在一定程度上减轻鲶爱德华氏菌感染导致的肝、脾、肾损伤,其中600目作用效果优于200目。     

Survival and Antibody Response of Channel Catfish,Blue Catfish,and Channel Catfish Female × Blue Catfish Male Hybrids after Exposure to Edwardsiella ictaluri

Abstract

Juvenile Norris strain channel catfish Ictalurus punctatus, blue catfish I. furcatus, and Norris strain channel catfish female × blue catfish male hybrids were challenged with Edwardsiella ictaluri by bath immersion or intraperitoneal injection (high or low dose) in aquaria. Survival (%) after bath immersion was highest for blue catfish (89.5 ± 2.8), intermediate for hybrids (73.8 ± 6.7), and lowest for channel catfish (62.0 ± 4.2). Prechallenge antibody levels to E. ictaluri, measured by enzyme-linked immunosorbent assay, were negative (mean ± SE optical density [OD] = 0.010 ± 0.003). Postchallenge antibody response for blue catfish (OD = 0.132 ± 0.045) was significantly lower than that of channel catfish (OD = 0.350 ± 0.045), whereas the response of the channel × blue catfish F₁ hybrids (OD = 0.263 ± 0.051) was intermediate and not significantly different from either parental species. Intraperitoneal injections of E. ictaluri resulted in significant mortality only in channel catfish (88.3 ± 2.6% survival) and were sublethal to hybrid catfish and blue catfish with 100.0% and 99.3 ± 0.4% survival, respectively. Antibody responses after the injection challenge were significantly different among catfish groups and injection dose with no group × dose interaction. Antibody responses after the injection challenge were consistent with the immersion challenge, and means of high and low challenge doses were lowest in blue catfish (OD = 0.061 ± 0.014), intermediate in hybrids (OD = 0.187 ± 0.014), and highest in channel catfish (OD = 0.272 ± 0.014). For all fish groups combined, the high injection challenge dose resulted in higher antibody levels (OD = 0.206 ± 0.011) than low injection challenge dose (OD = 0.140 ± 0.012). Overall results indicate greater resistance to E. ictaluri and lower antibody response in blue catfish, and show the potential to identify molecular markers linked with disease resistance and introgression of resistance genes from blue catfish into channel catfish.     

Effect of water temperature on the clinical outcome of infection with Edwardsiella ictaluri in channel catfish

Channel catfish fingerlings (mean body weight, 19 +/- 3 g each) were given intraperitoneal inoculations of Edwardsiella ictaluri suspensions of 10(4), 10(5), or 10(6) bacteria. Control fish were inoculated intraperitoneally with sterile 0.85% NaCl solution. Ten-day trials were conducted at water temperatures of 17, 21, 23, 25, 28, and 32 C. Differences in mortality between E ictaluri-infected fish and fish used as controls were observed at water temperatures of 23, 25, and 28 C, but not at temperatures of 17, 21, and 32 C. Clinical signs and lesions induced by intraperitoneal inoculation of E ictaluri were comparable with those found with the intestinal form of the natural disease. The characteristic erosion of skin and muscle overlying the skull, known as the "hole-in-the-head" lesion, was not observed. A given fish may be susceptible to infection at any water temperature, but a population is at risk when water temperatures are in the 22 to 28 C range.     

Use of vaccination against enteric septicemia of catfish and columnaris disease by the U.S. catfish industry

Vaccination is an effective strategy used for the protection of food animals against infectious diseases. A 2010 U.S. Department of Agriculture questionnaire examined U.S. catfish industry use (in 2009) of two commercial vaccines that provide protection against enteric septicemia of catfish (ESC) and columnaris disease, catfish producers' opinions regarding the percentage of vaccinated fish they expect to be protected, and producers' general expectations regarding survival of vaccinated fish compared with unvaccinated fish. During 2009, 9.7% of the total fingerling operations used one or both vaccines; 12.3% of the total industry fry production was vaccinated against ESC, and 17.0% was vaccinated against columnaris disease. Of the producers who grew food-sized catfish to harvest, 6.7% used vaccinated catfish. The farms that did not use vaccinated fish for grow out had a mean size of 63.4 water surface hectares (156.6 water surface acres). The operations that used vaccinated fish were larger (mean size = 206.6 water surface hectares, or 510.6 water surface acres). The producers that stocked ESC-vaccinated fish for grow out represented 19.0% of the total water surface area of food fish production; producers that stocked columnaris-vaccinated fish represented 16.6% of the total area. Of the producers that stocked ESC-vaccinated catfish, 41.9% thought that survival was better in vaccinated fish than in unvaccinated fish; of the producers that stocked columnaris-vaccinated catfish, 46.2% thought that vaccinated fish displayed better survival. However, 37.5% of producers that used the ESC vaccine and 39.7% of producers that used the columnaris vaccine did not know whether vaccination improved survival rates. When all producers were asked about their expectations regarding the percentage of vaccinated fish that would be protected from disease, 52.4% responded that they expected 100% of their fish to be protected. More producer information about reasonable expectations regarding vaccine efficacy, the conditions under which immunosuppression and vaccine failure can occur, and assessment of vaccine performance may result in increased use of vaccination as a tool for the catfish industry.     

Immersion booster vaccination effect on sea bass (Dicentrarchus labrax L.) juveniles

In each challenge 30 sea bass juveniles (mean weight 3.3 +/- 0.2 g SD) were used. During the whole experiment (water T: 18 +/- 1 degrees C) the fish were held in four 50l seawater independent recirculation systems (one fish group per 50l system). The protection to the pathogen Vibrio anguillarum was tested on booster vaccinated sea bass (Dicentrarchus labrax L.) juveniles. The vaccination was performed by immersion for 60 s in a commercial anti-V. anguillarum vaccine suspension. Booster vaccination took place 60 days after the initial immunization. Thirty days after the booster vaccination all the fish received intraperitoneally (IP) 3.0 x 10(6) cfu/fish (colony forming units) virulent V. anguillarum bacteria. The booster vaccination showed a strong protection effect on the challenged sea bass. In the next 20 days after the challenge the mortality was 0% among the booster vaccinated sea bass, 10% among the once vaccinated fish and 50% in the control group (unvaccinated fish). No mortality was observed among the unvaccinated sea bass injected IP with sterile normal saline by the challenge.     

Oral Vaccination of Channel Catfish against Enteric Septicemia of Catfish Using a Live Attenuated Edwardsiella ictaluri Isolate

Enteric septicemia of catfish (ESC), caused by Edwardsiella ictaluri, is the most problematic bacterial disease affecting catfish aquaculture in the southeastern United States. Efforts to develop an effective ESC vaccine have had limited industrial success. In commercial settings, ESC vaccines are typically administered by immersion when fry are transferred from the hatchery to rearing ponds. While this approach is a practical method of mass delivery, this strategy administers vaccines to very young fish, which lack a fully developed immune system. To circumvent this limitation, an oral vaccination strategy was evaluated as a means of immunizing catfish at the fingerling stage of production, when fish possess a more complete immune arsenal. A virulent E. ictaluri isolate (S97-773) was attenuated by successive passage on media containing increasing concentrations of rifamycin. In laboratory trials, cultured vaccine was diluted and mixed with feed (100 mL diluted vaccine/454 g feed). This mixture was then fed to Channel Catfish Ictalurus punctatus fingerlings. Two separate dilutions of cultured vaccine (1:10 and 1:100) were used to create the vaccine–feed mixture, equating to estimated doses of 5 × 10⁷ and 5 × 10⁶ CFU/g of feed, respectively. After 30 d, catfish were exposed by immersion (1 × 10⁶ CFU/mL) to the virulent parental strain of E. ictaluri. The target dose (1:100 dilution, ～5 × 10⁶ CFU/g of feed) offered exceptional protection (relative percent survival = 82.6–100%). In addition, negligible deaths occurred in fish vaccinated at 10 times the target dose (1:10 dilution, ～5 × 10⁷ CFU/g of feed). In pond trials, antibody production increased 18-fold in orally vaccinated fish. When compared with nonvaccinated controls, vaccination significantly improved survival, feed fed, feed conversion, biomass produced, and total harvest. This research demonstrates Channel Catfish can be successfully immunized in a commercial setting against E. ictaluri with a single dose of an orally delivered, live attenuated, E. ictaluri vaccine.

Received July 31, 2014; accepted March 2, 2015     

Effect of common aquaculture chemicals against Edwardsiella ictaluri and E. tarda

Edwardsiellosis is an important bacterial infection of freshwater and marine fishes. Edwardsiella ictaluri causes enteric septicemia of catfish, and E. tarda causes emphysematous putrefactive disease of catfish and fish gangrene in various species; these diseases have considerable economic effects on the aquaculture industry. In addition, E. tarda is an important zoonotic pathogen. Thus, the reduction or elimination of these pathogens from an aquarium or aquaculture facility is imperative. This study examined a variety of commercially available chemicals for their ability to reduce or eliminate E. ictaluri and E. tarda from the aquatic environment. The various concentrations of chemicals were tested in vitro in microcentrifuge tubes with a known concentration of bacteria at room temperature. In this study, ethyl alcohol (30, 50, or 70%), benzyl-4-chlorophenol/phenylphenol (1%), sodium hypochlorite (50, 100, 200, or 50,000 mg/L), n-alkyl dimethyl benzyl ammonium chloride (1:256), povidone iodine (50 or 100 mg/L), glutaraldehyde (2%), and potassium peroxymonosulfate/sodium chloride (1%) were effective disinfectants, as each reduced or eliminated the number of detectable organisms within 1 min of contact time. However, neither Chloramine-T (15 mg/L) nor formalin (250 mg/L) substantially reduced bacterial counts even after 60 min of contact time.     

Measles vaccine in dogs: efficacy against aerosol challenge with virulent canine distemper virus.

Fifty young Beagle pups were used in studies on the efficacy of measles virus vaccine in providing protection against virulent canine distemper (CD) virus given intranasally. Among 29 dogs vaccinated with measles virus vaccine and subsequently exposed to virulent CD virus, 1 died, 7 developed relatively severe signs of CD, 15 had mild signs of distemper, and 6 remained clinically normal. Of 15 unvaccinated dogs similarly exposed to virulent CD virus, 11 succumbed to distemper. Six pups vaccinated with modified live-virus (MLV) CD virus vaccine remained clinically normal following immunity challenge.