Safety and efficacy of colchicine for the prevention of post-operative atrial fibrillation in patients undergoing cardiac surgery: a meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

Colchicine is an anti-inflammatory drug that may prevent post-operative atrial fibrillation (POAF). The effect of this drug has been inconsistently shown in previous clinical trials. We aimed to compare the efficacy and safety of colchicine vs. placebo to prevent POAF in patients undergoing cardiac surgery.

METHODS AND RESULTS

A systematic search of EMBASE, MEDLINE, SCOPUS, ClinicalTrials.gov, and the Cochrane Library for randomized controlled trials (RCTs) was conducted from inception till April 2023. The primary outcome was the incidence of POAF after any cardiac surgery. The secondary outcome was the rate of drug discontinuation due to adverse events and adverse gastrointestinal events. Risk ratios (RR) were reported using the Mantel Haenszel method. A total of eight RCTs comprising 1885 patients were included. There was a statistically significant lower risk of developing POAF with colchicine vs. placebo (RR: 0.70; 95% CI: 0.59-0.82; P < 0.01, I2 = 0%), and this effect persisted across different subgroups. There was a significantly higher risk of adverse gastrointestinal events (RR: 2.20; 95% CI: 1.38-3.51; P < 0.01, I2 = 55%) with no difference in the risk of drug discontinuation in patients receiving colchicine vs. placebo (RR: 1.33; 95% CI: 0.93-1.89; P = 0.11, I2 = 0%).

CONCLUSION

This meta-analysis of eight RCTs shows that colchicine is effective at preventing POAF, with a significantly higher risk of adverse gastrointestinal events but no difference in the rate of drug discontinuation. Future studies are required to define the optimal duration and dose of colchicine for the prevention of POAF.

Efficacy of vaccines in chickens against highly pathogenic Hong Kong H5N1 avian influenza

In 1997, highly pathogenic (HP) H5N1 avian influenza virus (AIV) caused infections in poultry in Hong Kong and crossed into humans, resulting in a limited number of infections including 18 hospitalized cases and six associated deaths. The unique ability of this, AIV to infect both poultry and people raised a concern for the potential of humans to be biological as well as mechanical vectors of this AIV to poultry. The current study was undertaken to determine if existing vaccines and their technologies could be used during an outbreak to protect poultry. Commercial and experimental inactivated whole H5 AIV and baculovirus-expressed AIV H5 hemagglurinin protein vaccines provided protection from clinical signs and death in chickens after lethal challenge by human-origin HP H5N1 Hong Kong strains 156/97 and 483/97. The commercial and experimental inactivated vaccines had mean protective doses ranging from 0.25 to 0.89, which represents the milligrams of viral protein in the vaccines that provided protection from death in half of the birds. Furthermore, the vaccines reduced the ability of the challenge AIV to replicate in chickens and decreased the recovery of challenge AIV from the enteric and respiratory tracts, but the use of a vaccine will nor totally prevent AI virus replication and shedding. Existing vaccines will protect poultry from mortality and reduce virus replication from the new HP AIV strain that can infect both poultry and humans.

Genetic determinants of altered virulence of Taiwanese foot-and-mouth disease virus

In 1997, a devastating outbreak of foot-and-mouth disease (FMD) in Taiwan was caused by a serotype O virus (referred to here as OTai) with atypical virulence. It produced high morbidity and mortality in swine but did not affect cattle. We have defined the genetic basis of the species specificity of OTai by evaluating the properties of genetically engineered chimeric viruses created from OTai and a bovine-virulent FMD virus. These studies have shown that an altered nonstructural protein, 3A, is a primary determinant of restricted growth on bovine cells in vitro and significantly contributes to bovine attenuation of OTai in vivo.

Effective poultry programming in the next century. Poultry research: basic versus applied

The debate over the relative merit of basic vs applied research has been going on for as long as there has been research. This debate could be resolved in many instances by better communication so that those who question the need for basic studies can see how basic findings can contribute directly and indirectly to the resolution of real problems. Applied research directed at problem-solving is usually dependent upon those facts that have been revealed by basic researchers. This is a debate that should be set aside. The poultry industry must have contributions from both the basic and applied researchers to remain competitive and produce those products society depends upon.

Out on the farm with DNA vaccines

DNA vaccination is a rapidly developing technology that offers new approaches for the prevention of disease. This technology may permit the production of new vaccines against diseases that have no current vaccine, as well as allowing the development of improved vaccines to replace existing products. We describe how DNA vaccination is being developed for use in commercial animal production, with an emphasis on viral diseases, and discuss the existing hurdles to its development and use.

Interaction of mouse adenovirus type 1 early region 1A protein with cellular proteins pRb and p107

We demonstrated functional associations between mouse adenovirus type 1 (MAV-1) early region 1A (E1A) protein and both the mouse retinoblastoma protein (pRb) and the mouse pRb-related protein, p107. Interactions between MAV-1 E1A and mouse pRb or mouse p107 proteins were examined in infected cell lysates using a mouse embryonic fibroblast cell line infected with wild-type and mutant MAV-1 viruses. Using a polyclonal antibody to MAV-1 E1A, exogenously added mouse pRb or mouse p107 was coimmunoprecipitated from wild-type, dIE105 (CR1 delta)-, and dIE106 (CR3 delta)-infected cell lysates. No coimmunoprecipitation was seen with cell lysates from dIE102 (CR2 delta) or pmE109, a mutant virus that produces no detectable E1A protein due to an ATG to TTG point mutation in the initiator methionine. Introduction of mouse pRb into SAOS-2 cells resulted in a flat and enlarged cell phenotype, whereas cotransfection of mouse pRb and MAV-1 E1A resulted in a significant reduction of flat cells, presumably due to E1A binding pRb. CR1 delta and CR2 delta E1A proteins were less effective at reducing the number of flat, enlarged cells induced by pRb expression than were the CR3 delta or wild-type E1A proteins. The reduced ability of these mutants to inactivate pRb relative to wild-type E1A correlated with their reduced ability to bind pRb in the in vitro coimmunoprecipitation experiments. As a measure of p107/MAV-1 E1A complex formation in MAV-1-infected cells, we used mobility shift assays to examine cell extracts for the presence of p107-containing E2F protein-DNA complexes. Mock-, dIE102-, and pmE109-infected cell extracts formed a p107-containing complex, whereas wild-type-infected cell extracts did not. Thus the formation of a p107-E2F complex in wild-type- or these mutant-infected extracts inversely correlated with the presence of E1A-p107 complexes identified in the vitro coimmunoprecipitation experiments. This is consistent with E1A-p107 complexes forming in wild-type MAV-1-infected cells.

Analysis of early region 3 mutants of mouse adenovirus type 1

Early region 3 (E3) of mouse adenovirus type 1 has the potential to produce three proteins which have identical amino termini but unique carboxy-terminal sequences. Three recombinant deletion viruses were constructed so that each could produce only one of the three E3 proteins. A fourth mutant that should produce no E3 proteins was also constructed. These recombinants were able to grow in mouse 3T6 cells and produced wild-type levels of viral mRNAs and proteins except for those specifically deleted by the mutations. Early mRNA production from the mutant viruses was analyzed by reverse transcriptase PCR and confirmed that each deletion mutant would be able to produce only one of the three E3 proteins. Late mRNA production was analyzed by Northern (RNA) blotting and found to be similar in wild-type and mutant viruses. Capsid morphology was unaltered in the mutant viruses as seen by electron microscopy. Immunoprecipitation of E3 proteins from infections of mouse 3T6 cells using an antiserum specific for all three E3 proteins was used to examine the effect of the introduced mutations on protein expression. Two mutants produced only one class of E3 protein as predicted from their specific mutations and mRNA expression profiles. One mutant virus failed to produce any detectable E3 proteins. The predicted E3-null mutant was found to be leaky and could produce low levels of E3 proteins. Outbred Swiss mice were infected with the E3 mutant viruses to determine if the E3 proteins have an effect on the pathogenicity of the virus in mice. All of the mutants showed decreased pathogenicity as determined by increased 50% lethal doses, indicating that the proteins of the E3 region are important determinants of the pathogenesis of mouse adenovirus in its natural host.

Characterization of an 11K protein produced by early region 3 of mouse adenovirus type 1

Early region 3 (E3) of mouse adenovirus type 1 produces three mRNAs that can encode three proteins with unique carboxy-terminal exons. A bacterial fusion protein encoding the unique terminus of one the three predicted proteins was used to generate antiserum in rabbits. This antiserum detected a 14K protein on a Western blot of infected cell lysates. Immunoprecipitation and endoglycosidase H digestion revealed that the 14K protein was a glycoprotein with a core molecular weight of 11K, and we are designating this protein E3 gp 11K. Through in vitro translation experiments we determined that the previously predicted signal sequence of gp11K was cleaved when the protein was expressed during an infection. Biochemical and immunofluorescence microscopy data indicated that E3 gp11K was localized to the endoplasmic reticulum of infected cells. Biochemical experiments further indicated that gp11K is a peripheral membrane protein.

Research to understand and control Salmonella enteritidis in chickens and eggs

When it became evident that the association of human Salmonella enteritidis (SE) outbreaks with the consumption of contaminated Grade A eggs posed a threat to public health and to the economic viability of the egg industry, research programs were rapidly initiated to investigate the many unanswered questions about SE in eggs and chickens. Research efforts have focused on the dynamics of deposition, survival, and growth of SE in eggs, the pathogenesis of SE in chickens, strategies for detecting SE-infected flocks, opportunities for intervening to prevent infection, the sources of SE in laying flocks, options for effectively cleaning poultry houses, and the epidemiology of SE infections of humans and chickens. This research has provided a substantially better understanding of the SE problem in poultry, but many further questions about the basis for and the prevention of eggborne transmission of SE remain to be answered.

Comparative efficacy of the B-1 and VG/GA vaccine strains against velogenic viscerotropic Newcastle disease virus in chickens

Groups of eight 1-day-old white rock chickens were vaccinated with either B-1 or VG/GA strain of Newcastle disease virus (NDV) by eyedrop instillation. Some of the chickens were vaccinated a second time at 17 days of age. Eight groups of chickens vaccinated either once or twice were challenged with the California 1083 strain of velogenic viscerotropic Newcastle disease virus (VVNDV) at 30 days of age by either intramuscular injection or eyedrop instillation. One group of unvaccinated control chickens was challenged by eyedrop instillation. All eight unvaccinated controls, two of the 16 B-1 vaccinates, and none of the 16 VG/GA vaccinates died following challenge. There were no obvious differences in pre-challenge serum antibody levels among the vaccinates. Only the twice-vaccinated chickens that were challenged by eyedrop and the unchallenged vaccinates failed to show a marked rise in serum antibody titers. The VG/GA strain of NDV provided protection against the mortality associated with VVNDV challenge similar to that provided by the B-1 strain within the conditions of this experiment.

Effect of route of administration on the efficacy of a recombinant fowlpox virus against H5N2 avian influenza

A recombinant fowlpox vaccine virus containing the H5 hemagglutinin gene of avian influenza virus was administered to susceptible chickens via wing-web puncture, eye drop, instillation into the nares, and drinking water. Even though there was a negligible hemagglutination-inhibition (HI) serologic response, all 10 chickens vaccinated by wing-web puncture remained without obvious signs of disease and survived challenge with a highly pathogenic strain of H5N2 avian influenza virus. All unvaccinated chickens and those vaccinated by nasal and drinking-water routes died following challenge. Eight of 10 chickens vaccinated with the recombinant by eyedrop died. All vaccinates were negative on the agar gel precipitin (AGP) test, and only one chicken had a positive HI titer before challenge. All chickens that survived challenge had high levels of HI antibody and were positive on the AGP test, indicating that they were infected by the challenge virus.

Evaluation of the efficacy of an oil-emulsion bacterin for protecting chickens against Salmonella enteritidis

To assess the potential protective efficacy of a Salmonella enteritidis bacterin, an acetone-killed oil-emulsion vaccine was prepared from a phage type 13a S. enteritidis strain and administered subcutaneously to hens in two experiments. Hens were housed individually, and every other hen was vaccinated (at 23 weeks of age in one experiment and at 45 weeks in the other). A second (booster) bacterin injection was administered 6 weeks later in both experiments. Three weeks after the second vaccination, all hens were challenged with an oral dose of approximately 10(9) cells of a heterologous (phage type 14b) S. enteritidis strain. In both trials, S. enteritidis was isolated from fewer internal organs (spleens, ovaries, and oviducts) and pools of egg contents from vaccinated hens than from unvaccinated control hens. Vaccination did not, however, affect the percentage of hens that shed S. enteritidis in feces in either experiment.

A feather-trap system for the removal of chicken feathers from laboratory sewage

A simple feather-trap system is described for use on the drain lines of buildings housing poultry for research or other purposes where floors are frequently washed. The trap uses disposable plastic-mesh bags that can efficiently remove almost all feathers from the water, preventing sewer lines from being blocked by compacted feathers. Critical measurements and operational procedures are described.

Detection and Enumeration of Salmonella enteritidis in Fresh and Stored Eggs Laid by Experimentally Infected Hens

Laying hens were orally inoculated with a phage type 13a strain of Salmonella enteritidis (SE). Eggs laid by the infected hens were collected daily between the 4th and 14th d postinoculation and randomly allocated into three groups. One group of eggs was sampled on the day of collection, one group was held for 7 d at 7.2°C before sampling, and one group was held for 7 d at 25°C before sampling. The frequency and level of detectable contamination of egg contents by SE were determined for each group. Only 3% of the freshly laid eggs and 4% of the eggs held for 7 d at refrigerator temperature were identified as having SE-contaminated contents, whereas SE was isolated from the contents of 16% of eggs held for 7 d at room temperature. Enumeration of SE in contaminated eggs indicated greater numbers of SE in eggs held for 7 d at 25°C than in eggs from the other two groups, although most contaminated eggs in all three groups contained relatively small numbers of SE (generally less than 10/ml and rarely exceeding 100/ml).

Evaluation of a chick mortality model for predicting the consequences of Salmonella enteritidis infections in laying hens

The effects of four domestic Salmonella enteritidis (SE) isolates were compared in experimentally infected chicks and laying hens. The pathogenicity of each strain for 1-day-old chicks was determined by recording postinoculation mortality. The effects of the SE strains on adult hens were measured in terms of changes in total egg production, the frequency of production of SE-contaminated eggs, the dissemination of SE to internal organs, and the elicitation of a specific antibody response. Significant differences in the consequences of infection with different SE strains were observed in mortality rates among chicks and in total egg production, the frequency of production of contaminated eggs, and the serum antibody response among laying hens. The usefulness of a chick mortality model for predicting the probable frequency of production of contaminated eggs by laying hens infected with particular SE strains was then further evaluated by infecting chicks and laying hens with four other field isolates of SE. Although significant differences between SE strains were observed in both chick mortality and the frequency of production of contaminated eggs by hens, a strong correlation between these two parameters was not evident.

Detection of Salmonella serogroup D-specific antibodies in the yolks of eggs laid by hens infected with Salmonella enteritidis

Eggs laid by hens experimentally infected with Salmonella enteritidis were assayed for the presence of Serogroup D-specific yolk antibodies. Yolk antibodies were detected with S. enteritidis and Salmonella pullorum antigens in the microantiglobulin test as early as 9 days after inoculation of hens with S. enteritidis. Yolk antibody titers reached peak levels at 3 to 5 wk postinoculation and remained at detectable levels for at least 7 wk postinoculation in eggs from both orally inoculated and horizontally contact-exposed hens. Eggs laid by hens from commercial flocks implicated in epidemiological investigations of human S. enteritidis outbreaks were also tested. Serogroup D-specific yolk antibodies were detected in 5 to 22% of eggs from hens in houses identified as infected by bacteriological culturing of internal organs of hens for S. enteritidis.

Protection of chickens against highly pathogenic avian influenza virus (H5N2) by recombinant fowlpox viruses

Two recombinant fowlpox viruses containing the avian influenza H5 hemaglutinin (HA) gene were evaluated for their ability to protect chickens against challenge with a highly pathogenic isolate of avian influenza virus (H5N2). Susceptible chickens were vaccinated with the parent fowlpox vaccine virus or recombinant viruses either by wing-web puncture or comb scarification. Following challenge 4 weeks later with highly pathogenic avian influenza virus, all birds vaccinated by the wing-web method were protected by both recombinants, while 50% and 70% mortality occurred in the two groups of birds vaccinated by comb scarification. Birds vaccinated with the unaltered parent fowlpox vaccine virus or unvaccinated controls experienced 90% and 100% mortality, respectively, following challenge. Hemagglutination-inhibition (HI) antibody levels were low, and agar-gel precipitin results were negative before challenge. Very high HI titers and positive precipitating antibody responses were observed in all survivors following challenge.

Amantadine resistance among hemagglutinin subtype 5 strains of avian influenza virus

Several avian influenza virus strains of hemagglutinin subtype 5 were assayed for sensitivity to the antiviral drug amantadine. Most strains exhibited little sensitivity to the drug as measured by plaque reduction. The A/Chicken/Scotland/59 (CS59), however, was highly sensitive, making it easily distinguishable from the other H5 strains. Drug sensitivity of the viruses was also assayed in chicken embryos. The in ovo patterns of amantadine sensitivity differed from those detected in cell culture. The CS59 isolate could not be distinguished from all the other strains on the basis of its response to amantadine in ovo. Although amantadine protected chickens inoculated with CS59 from morbidity and mortality, drug-resistant viruses were readily isolated from the infected birds. As found with other amantadine-resistant variants, the structure of the matrix gene was altered in the resistant isolates. These results demonstrate that amantadine resistance is widespread among avian influenza viruses of the H5 subtype, that drug sensitivity in cell culture does not necessarily reflect responses to amantadine in ovo and in vivo, and, as previously found, amantadine-resistant derivatives of H5 strains may be isolated from birds protected by the drug.

Early region 4 sequence and biological comparison of two isolates of mouse adenovirus type 1

The DNA sequence of 88-100 map units of mouse adenovirus type 1 (MAV-1) was determined. One translational open reading frame showed 48% sequence similarity to a human adenovirus type 2 early region 4 protein. Based on the protein similarity, genome location, and transcriptional polarity, we concluded that this region of MAV-1 corresponds to early region 4. A 241-bp sequence consisting of 10 imperfect direct repeats with sequence similarity to minisatellite DNA was found in this region. Two virus isolates with different passage histories were examined and were found to have a sequence polymorphism within this region. The two viruses were compared for growth in cell culture and mice and small quantitative differences were observed only in vivo.

Isolation of Salmonella enteritidis from internal organs of experimentally infected hens

Tissues from experimentally infected hens were examined for the presence of Salmonella enteritidis (SE). SE was recovered from internal organs of both orally inoculated hens and hens infected by horizontal contact transmission. SE was isolated from 58% of the ceca, 51% of the livers, 47% of the spleens, 17% of the ovaries, and 17% of the oviducts of hens sampled during the first 5 weeks after exposure. SE was recovered at a low frequency from all internal organs sampled for as long as 22 weeks after exposure.

Serological detection of experimental Salmonella enteritidis infections in laying hens

The antibody response of laying hens to experimental Salmonella enteritidis infection was evaluated in microagglutination, tube agglutination, and rapid whole-blood plate agglutination assays. Hens of three different ages were infected by either oral inoculation or horizontal contact transmission. Blood was collected at weekly intervals, and the presence of specific antibodies was assessed by reaction with antigens prepared from strains of S. enteritidis and S. pullorum. The sensitivity of detection of infected hens did not vary significantly between the assays, as all three tests effectively identified most exposed hens as seropositive. Within each test, however, variation was observed in the detection sensitivity when different antigens were used. The microagglutination titers of serum samples were determined by serial dilution. Antibody titers peaked at 1 to 2 weeks postinoculation and declined steadily, although most birds were still identified as seropositive at 10 weeks postinoculation. The mean microtest titers obtained with S. enteritidis antigens were higher than with an S. pullorum antigen, indicating greater test sensitivity. However, use of the S. pullorum antigen resulted in fewer false positives when sera from uninfected control hens were tested. The titers of contact-exposed hens peaked later and at lower values than did those of inoculated hens, but these two groups of hens had similar antibody titers after the third week postinoculation.

Production of Salmonella enteritidis-contaminated eggs by experimentally infected hens

Laying hens of three different ages were experimentally infected with a strain of Salmonella enteritidis by either oral inoculation or contact transmission. Total egg production was depressed in exposed hens of all three age groups. Persistent intestinal shedding was observed in a small number of hens. Eggs with contents contaminated by S. enteritidis were produced by exposed hens at a high frequency, but only during a fairly short period of time that extended through approximately 1 week postinoculation for older hens and through 2 weeks for younger hens. S. enteritidis was recovered from whole yolks and albumen of these eggs at similar frequencies, but not from the content of yolks. Eggs with contaminated shells were also produced, but at a lower frequency. Contaminated eggs were produced by orally inoculated and contact-exposed hens at similar frequencies. S. enteritidis was not isolated from the contents of eggs laid by hens infected with other S. enteritidis strains.

Transcription mapping of mouse adenovirus type 1 early region 3

Early region 3 (E3) of mouse adenovirus type 1 was analyzed using S1 nuclease protection and primer extension assays, cDNA sequencing, and genomic sequencing. We present the genomic sequence from 79 to 83 map units of the viral genome, the precise ends and splice sites of the E3 mRNAs, and the predicted protein sequence encoded by the mRNAs. Three major classes of early mRNAs were identified; all were approximately 1 kb long, consisted of three exons, and shared 5' and 3' ends. The three classes had alternative splicing at the junction between the second and third exon. The three proteins predicted by the three mRNAs were slightly similar to the E3 19K glycoprotein of human adenovirus type 3; the longest of the three was the most similar. Open reading frames corresponding to late proteins were also identified in the translated mouse adenovirus type 1 DNA sequence. In mouse adenovirus, as in the human adenoviruses, L4 overlaps E3, and L5 starts just downstream of the E3 region.

Age-related changes in the persistence and pathogenicity of Salmonella typhimurium in chicks

Effects of age at exposure on the persistence of Salmonella in various tissues of chicks were assessed in two experiments. Broiler chicks, housed on wire floors in isolation cabinets, were orally inoculated with S. typhimurium at various ages (1 to 8 days after hatching). The postinoculation mortality of chicks declined significantly (P less than .05) as the age at inoculation increased. One experiment investigated the effect of age at inoculation on the persistence of S. typhimurium in the cecum. Salmonella persisted for 7 wk after inoculation in 81.3% of the chicks inoculated at 1 day of age and in 62.5% of the chicks inoculated at 8 days of age. The mean number of cecal Salmonella at 7 wk postinoculation was also greater for chicks inoculated on Day 1 than for those inoculated on Day 8. The second experiment examined the effect of age at inoculation on the adherence of S. typhimurium to and penetration through the cecal epithelium. The ceca of chicks inoculated at 1 day of age were colonized by significantly more adhering Salmonella at 2 days postinoculation (1.4 x 10(8)/g) than were those of chicks inoculated at 3, 5, or 7 days of age (8.0 x 16(6)/g or less), but age did not affect the recovery of S. typhimurium from livers or spleens.

Pathogenicity of Escherichia coli in aerosols for young chickens

The relative pathogenicity of Esherichia coli isolates from poultry was determined by aerosol exposure of young chickens. Evidence of colisepticemia with airsacculitis and/or pericarditis and perihepatitis was evaluated. A system was devised that included the intratracheal (IT) inoculation of strain SE-17 infectious bronchitis virus (IBV) of chicks at 7 days of age followed by their aerosol exposure to E. coli culture suspensions 2 days later. Each experiment was terminated 6 days later. For comparative purposes in some studies, chicks were housed at 17 C and others at 27 C. The IBV-E. coli challenge procedure proved to be an effective way to determine the relative ability of E. coli isolates to cause death and/or gross lesions in young chickens. With some E. coli isolates, there were minimal or no obvious adverse effects from exposure except when chickens were previously inoculated with IBV. When chicks were housed at 17 C instead of 27 C, slight increases in mortality and decreases in gross lesions were generally observed, probably because the earlier deaths did not allow time for the lesions to become as evident. The E. coli isolate #18344 (Congo Red-positive) was consistently more pathogenic than the Congo Red-negative version of that isolate. Cultures of E. coli previously demonstrated to be pathogenic (VA O1:K1 and DL #29) were among the most pathogenic isolates evaluated in these experiments and were similar to the Congo Red-positive #18344 isolate.(ABSTRACT TRUNCATED AT 250 WORDS)

Recent advances in filtered-air positive-pressure (FAPP) housing for the production of disease-free chickens

Design and performance information on a filtered-air positive-pressure (FAPP) housing system for disease-free poultry flocks is presented. The system includes many special features that result in excellent biological security, easy cleanup and maintenance, efficient control of environment, and a centralized alarm in the event of problems. The system has now housed eight flocks without any major problems. Based on its performance thus far, it should be useful as a reliable housing system for disease-free poultry.

Genome organization of mouse adenovirus type 1 early region 1: a novel transcription map

Mouse adenovirus type 1 (MAV-1) genomic DNA from 8.9 to 13.7 map units was sequenced and the early region 1 (E1) transcription map was determined by S1 nuclease, primer extension, and Northern analyses, and cDNA sequencing. The E1 transcription map of MAV-1 had marked dissimilarities from the conserved transcription maps of primate adenovirus E1s. One major E1A and two E1B mRNAs were identified in overlapping transcription units. The single E1A mRNA was composed of three exons; the last exon was coincident with the last exon of the E1B mRNAs. While human adenovirus type 2 (Ad2) utilizes alternate splice donors for the first E1A mRNA exon, MAV-1 does not. Thus, no protein is predicted that would correspond to the Ad2 243 amino acid protein, although MAV-1 can encode a protein similar to the Ad2 289 amino acid protein (A. O. Ball, M. E. Williams, and K. R. Spindler, 1988, J. Virol. 62, 3947-3957). Two spliced E1B mRNAs differed from each other in an intron near the 5' end of the smaller E1B mRNA. This smaller mRNA could encode only the 55K E1B protein, while the larger mRNA could encode both the 21K and 55K E1B proteins.

Emergence of amantadine-resistant H5N2 avian influenza virus during a simulated layer flock treatment program

An experiment was designed to simulate field conditions in which preventive treatment is not initiated until after some chickens in a flock are infected with avian influenza (AI). Twelve hens began to receive amantadine hydrochloride on the day they were inoculated (day 0) with highly pathogenic AI virus, A/chicken/Pa/1370/83. These hens remained clinically normal through 8 days postinoculation (PI), but five died after day 9; mean death time (MDT) was 18 days. Three of 12 hens given amantadine beginning 1 day PI died (MDT 5.4 days), seven of 12 hens given amantadine beginning 3 days PI died (MDT 3.7 days), and all 12 inoculated hens not given amantadine died (MDT 4.9 days). The delayed mortality in the day 0 treatment group was likely due not to the original inoculum but to the emergence of a drug-resistant virus population. Virus isolated from a dead hen from that group was resistant to the actions of amantadine in both in ovo and in vivo tests. The lack of late mortality due to the drug-resistant virus in the day 1 and day 3 treatment groups, which were in close contact with the day 0 treatment group, was attributed to their becoming infected before treatment with the drug and to the development of protective immunity.

Influence of environmental temperatures on the serologic responses of broiler chickens to inactivated and viable Newcastle disease vaccines

Commercial and specific-pathogen-free (SPF) nonselected broilers were held at environmental temperatures that simulated the cyclic diurnal extremes for either hot (26.6 C-40.7 C) or moderate (18.3 C-32.3 C) summer temperatures. The chicks received either inactivated or viable La Sota Newcastle vaccines at various times after the initiation of the temperature extremes. When held at moderate temperatures for 7 days and then injected with inactivated vaccine, commercial chicks developed slightly higher but not statistically different levels of antibody compared with chicks held in the hot environment. In one experiment, the geometric mean serologic hemagglutination-inhibition responses of SPF chickens housed at extremely high temperatures for 4 days before being injected with inactivated vaccine were significantly greater (P less than or equal to 0.05) than those held at moderate temperatures. The reverse was apparent for chickens that received live vaccine virus after being in the hot environment for any of several lengths of time before vaccination.

Influence of dietary calcium stress on lethality of avian influenza viruses for laying chickens

The effect of calcium stress was studied in an attempt to reproduce lethal infections in laying chickens with A/Chicken/Alabama/75 (H4N8) influenza virus and with two nonpathogenic H5N2 influenza viruses from the 1983-84 outbreak in the eastern United States. Hens were fed calcium-deficient or standard diets for 7 to 14 days; then the calcium-deficient feed was replaced with standard feed supplemented with ad libitum oyster shell, and both groups of hens were inoculated with virus. When hens were infected with the H4N8 virus, respective mortalities of those on the calcium-deficient and standard diets were 19% (27/141) and 5% (7/143). The H5N2 viruses did not kill hens fed either diet. In standard pathogenicity tests, Alabama H4N8 viruses reisolated from the hens that died generally were more lethal for 4-week-old chickens than the stock virus. These results argue for characterization of the Alabama H4N8 virus as pathogenic rather than nonpathogenic as originally determined.

A comparison of Newcastle disease hemagglutination-inhibition test results from diagnostic laboratories in the southeastern United States

A two-phase comparison was conducted using the Newcastle disease hemagglutination-inhibition (HI) test to determine the variation of serologic results from poultry diagnostic laboratories in the southeastern United States. In the first phase of the comparison, most of the 17 participating laboratories in 10 states found the coded negative sera to be negative, and most found the potent sera to have the highest titers. However, there was a wide range of geometric mean titers (GMT's), from 2 to greater than or equal to 113 for the same serum samples. Each laboratory was strikingly consistent at reporting unknown but identical triplicate serum samples to have the same titer, even though the titers were frequently quite different from those of other laboratories. This observation indicated that currently used procedures yielded good reproducibility within individual laboratories but not necessarily between laboratories. In the second phase of the comparison, participants were furnished another set of coded sera, antigen, and a suggested incubation time. The implementation of the recommended incubation period reduced the extent of the lab-to-lab differences, but GMT's between labs still ranged from 11 to 95 on identical serum samples. When all laboratories used the same antigen, the average of the GMT results increased from 38 to 48, but the GMT's from the different laboratories ranged from 7 to more than 2048. Although the comparison exercise resulted in some improvement in uniformity, it was obvious that a continuing voluntary program should be initiated to certify laboratories and promote uniform test methods for specific serologic procedures using coded sera.

Chemotherapy and vaccination: a possible strategy for the control of highly virulent influenza virus

The influenza A virus [A/Chicken/Pennsylvania/1370/83 (H5N2)] that caused up to 80% mortality among chickens provided a model system for testing the efficacy of chemotherapeutic agents against highly virulent influenza virus. Amantadine and rimantadine administered in drinking water were efficacious both prophylactically and therapeutically. However, under conditions simulating natural transmission of virus, amantadine- and rimantadine-resistant viruses arose and were transmitted to other birds in contact with the infected chickens, causing mortality. Simultaneous administration of inactivated H5N2 vaccine and amantadine provided protection. Thus, chemotherapy may be useful in the treatment of a highly pathogenic influenza virus outbreak in humans or other animals when used in combination with vaccine.

The susceptibility of chicks to Salmonella montevideo in artificially contaminated poultry feed

Feed artificially contaminated with various levels of nalidixic-acid-resistant Salmonella montevideo was fed to newly hatched chicks for 7 days. Cloacal and cecal swabs were obtained from the chicks at 7, 14, and 21 days of age to monitor Salmonella colonization relative to the feed contamination level. In one of three trials, less than one Salmonella montevideo per gram of feed was sufficient to establish colonization in 1-to-7-day-old chicks.

Atypical disease produced in chickens by Newcastle disease virus isolated from exotic birds

Chickens were infected with a Newcastle disease virus (NDV) recovered from exotic birds with severe clinical disease and with lesions characteristic of viscerotropic velogenic Newcastle disease (VVND). The infection in chickens was inconsistently lethal, some infected chickens were not clinically affected, and gastrointestinal involvement was only marginally evident. Pathogenicity of the virus for chickens was not detectably altered by laboratory passage in chickens or by limit dilution passage in chicken embryos. The results suggest that the difference between velogenic NDV pathotypes may not always be distinct and that clinical manifestations of VVND in chickens may not always be predictable based on signs and lesions observed in exotic birds.

Experimental infection of laying chickens with adenovirus 127 and with a related virus isolated from ducks

Infection of commercially reared white leghorn and white rock hens with adenovirus 127 was associated with decreases in total egg production, external egg quality, egg weight (P less than 0.01), and eggshell thickness (P less than 0.01). The egg-production and egg-quality disturbances were transient, and production returned to normal approximately 4 weeks postinfection. Infection of white leghorns with a hemagglutinating adenovirus isolated from Missouri ducks did not adversely affect egg production, external egg quality, or eggshell thickness, but it was associated with decreased egg weight (P less than 0.01). Prior infection with the duck adenovirus prevented the adverse egg-production effects of adenovirus 127 infection. Mean hemagglutination-inhibition antibody titers of chickens infected with adenovirus 127 or with duck adenovirus ranged from 1:588 to 1:10809, and mean titers of uninfected chickens did not exceed 1:2.

Influence of formulation on the efficacy of experimental oil-emulsion Newcastle disease vaccines

Twenty-one experimental oil-emulsion vaccines with different emulsifier contents, aqueous-to-oil ratios, and antigen concentrations were compared by immunization of 4-week-old chickens. Vaccines that contained oil-phase (Arlacel 80) and aqueous-phase (Tween 80) emulsifiers induced 2-to-4-fold higher hemagglutination-inhibition titers than vaccines with only the oil-phase emulsifier. The emulsion vaccines containing both emulsifiers were also more stable at 37 C and less viscous than those containing only the oil-phase emulsifier. Vaccines that had different aqueous-to-oil ratios and contained different quantities of allantoic-fluid antigen (1.2% to 50% of the vaccine volume) induced similar protection against challenge, but hemagglutination-inhibition titers were proportional to the amount of antigen added. Vaccines that had different aqueous-to-oil ratios but contained equal amounts of antigen induced similar hemagglutination-inhibition titers and similar protection against challenge.

Comparison of three experimental inactivated oil-emulsion Newcastle disease vaccines

White Leghorn pullets vaccinated previously with live Newcastle disease virus (NDV) were revaccinated at point-of-lay with 3 experimental oil-emulsion (OE) Newcastle disease vaccines to determine whether immunogenicity of OE vaccines is influenced by emulsion composition differences. The vaccines used were formulated differently but contained equal amounts of inactivated NDV in stable, low-viscosity, water-in-oil emulsions. Serological responses to the vaccines differed (P less than 0.01), but 55 of 56 OE vaccinates remained clinically normal following challenge exposure with viscerotropic velogenic NDV 28 or 44 weeks after revaccination; 4 of 21 nonrevaccinated controls and all of 20 nonvaccinated challenge controls were clinically affected or died.

Collection and processing of blood samples dried on paper for microassay of Newcastle disease virus and avian influenza virus antibodies

A practical method for collection and processing of dried whole blood samples on filter paper was developed to facilitate large-scale testing programs for Newcastle disease virus and avian influenza virus antibodies. A modified paper punch was used to cut and place dried blood samples simultaneously in a standard 96-well microlate for elution of antibody. Twelve eluted samples were simultaneously transferred to another microplate for the hemagglutination-inhibition (HI) microtest. Similar HI titers were obtained with simultaneously collected serum and dried blood samples. Minor differences were not considered of practical importance in diagnostic serologic studies. Dried blood titers were not markedly affected by method of drying (37 C for 2 hours or 26 C for 4 hours), by storage for 24 hours before drying, or by storage of dried samples at 4 C for 28 days or 30 C for 14 days. Blood dried on paper was a satisfactory sample for assay of HI antibodies to Newcastle disease virus and avian influenza virus.

Embryonated eggs compared with fragments of chorioallantois attached to egg shell for isolation of Newcastle disease virus

The feasibility of using fragments of chorioallantois attached to egg shell (C-S) as an alternative to embryonated eggs for isolating Newcastle disease virus (NDV) was assessed. In paired titrations of 6 strains of virus, embryonated eggs detected an average of 6-to-7-fold greater amounts of virus than did C-S fragments. The efficiency of isolation of viscerotropic velogenic NDV from 240 swab samples was 97% in embryonated eggs and 84% in C-S fragments. Sensitivity differences between the 2 host systems were revealed only in tests of samples expected to contain small amounts of virus. These results suggest that C-S fragments can be reliably used in some but not all instances, thereby relieving logistic constraints sometimes associated with the use of embryonated eggs.

Immunization of chickens and turkeys against avian influenza with monovalent and polyvalent oil emulsion vaccines

Chickens and turkeys vaccinated with inactivated virus oil-emulsion vaccines containing different concentrations of either 1 (monovalent) or 4 (polyvalent) strains of avian influenza virus (AIV) were challenged-exposed with virulent AIV A/chicken/Scotland/59 or A/turkey/Ontario/7732/66. Four of 6 vaccines protected completely against postexposure mortality. Vaccine valency did not alter the serologic and challenge-exposure responses of chickens vaccinated with AIV A/turkey/Wisconsin/68, which was the virus component common to both monovalent and polyvalent vaccines. The magnitude of the serologic responses and protection against challenge-exposure were dependent on the concentration of virus in the vaccines. These data indicate that control of virulent AIV in chickens and turkeys by vaccination with inactivated vaccines may be feasible.

Preparation of inactivated oil-emulsion vaccines with avian viral or Mycoplasma antigens

The influence of the composition of water-in-oil emulsions on their physical characteristics was determined by preparing experimental emulsions with various water-to-oil ratios and various emulsifiers. Emulsions containing Tween 80 in the aqueous phase and Arlacel A or Arlacel 80 in the oil phase were lower in viscosity than emulsions containing only an oil-phase emulsifier. Viscosity decreased as the concentration of oil increased. Oil-emulsion vaccines prepared with aqueous- and oil-phase emulsifiers had low viscosity, were stable for more than 12 weeks at 37 C, and induced a marked primary antibody response in chickens.

The influence of test conditions on Newcastle disease hemagglutination-inhibition titers

Replicate samples of serum from chickens immune to Newcastle disease were titrated to determine the influence of certain test conditions on hemagglutination-inhibition (hi) titers. The test conditions studied were those most likely to vary in normal laboratory operations. The most marked effect on magnitude of HI titers was incubation time of twofold serum dilutions in antigen-saline; the average titer increase after incubation of the serum-antigen mixture for 1 hr at 37 C was log2 2.3 (fivefold). Twofold increases in virus concentration of the antigen-saline diluent caused an average titer reduction of log2 0.8. Shifts in HI titers were only minor with twofold changes in erythrocyte concentration (log2 0.3), with variations of test reading times from 0.5 to 2.0 hr (log2 0.1), and with variations in the period between preparation of the initial 1:10 serum dilution in antigen-saline and the subsequent serum dilutions (log2 0.3).

Use of the Nobuto blood-sampling paper strip for Newcastle disease serology

Dried whole blood collected by the paper-strip method of Dr. Kenzo Nobuto was evaluated for use in the Newcastle disease hemagglutination-inhibition (HI) test. When dried blood on the Nobuto strip was eluted in 1.0 ml of diluent, the resulting HI titers were similar to titers obtained with sera diluted 1:10. Both storage time and temperature influenced the stability of HI activity in dried blood, though the influence was minimal and is considered to have little significance in diagnostic serology, The advantages of this method of blood collection for Newcastle disease HI tests are discussed.

Electrocardiographic and respiratory responses to viscerotropic and neurotropic strains of Newcastle disease virus measured by radio telemetry

Two groups each of White Rock chickens from 6 to 23 weeks old were monitored by radio telemetry to determine their electrocardiogram and respiration response after they were infected with either a velogenic viscerotropic isolate of Newcastle disease virus (VVND) or the neurotropic GB strain of Newcastle disease virus (NGB). Significant changes were found in the heart rate, R wave amplitude, ST segment elevation, T wave amplitude, RS complex interval, ST segment duration T wave interval, TP segment duration, PR segment duration and TP interval of the birds infected with VVND, but no significant ECG changes were found in the birds infected with NGB. There were no significant changes in respiration rate in any birds.

Preparation of Newcastle disease virus hemagglutination-inhibition test antigen

A method of preparing antigen for Newcastle hemagglutination-inhibition (HI) tests is described; polyethylene glycol precipitation is used for the virus concentration. The virus was inactivated with either formalin or beta-propiolactone. Glycerin was used to stabilize the hemagglutinin activity of the antigen. The stability, uninfectivity, and slow eluting features of the antigen should aid in obtaining accurate HI results without the risks inherent in the use of live virus.