Evaluation of different chemical adjuvants on an avian influenza H6 DNA vaccine in chickens

This study assessed the ability of three adjuvants (aluminium hydroxide, Essai (microparticle) and Phema (nanoparticle)) to enhance the immune response of chickens to an H6N2 avian influenza DNA vaccine. No haemagglutination inhibition antibody was detected following two intramuscular immunizations with the adjuvanted and non-adjuvanted pCAG-HAk vaccine, which has previously been shown to induce moderate H6 haemagglutinin antibody response in SPF chickens. Following virus challenge, neither the vaccinated group without adjuvant nor the Essai-adjuvanted group showed a statistically significant reduction in virus shedding in oropharyngeal and cloacal swabs compared with the naive control group. However, the aluminium hydroxide and Phema-adjuvanted groups significantly reduced the frequency of virus shedding in oropharyngeal swabs, indicating that these adjuvants appeared to further enhance the vaccine potency. Aluminium hydroxide holds promise as an adjuvant for enhancing DNA-induced immune response in chickens owing to its low price and safety record.     

Salmonella enterica Serovar Enteritidis,England and Wales, 1945–2011

In England and Wales, the emergence of Salmonella enterica serovar Enteritidis resulted in the largest and most persistent epidemic of foodborne infection attributable to a single subtype of any pathogen since systematic national microbiological surveillance was established. We reviewed 67 years of surveillance data to examine the features, underlying causes, and overall effects of S. enterica ser. Enteritidis. The epidemic was associated with the consumption of contaminated chicken meat and eggs, and a decline in the number of infections began after the adoption of vaccination and other measures in production and distribution of chicken meat and eggs. We estimate that >525,000 persons became ill during the course of the epidemic, which caused a total of 6,750,000 days of illness, 27,000 hospitalizations, and 2,000 deaths. Measures undertaken to control the epidemic have resulted in a major reduction in foodborne disease in England and Wales.     

Avian influenza and ban on overnight poultry storage in live poultry markets, Hong Kong

We analyzed ≈12 years of surveillance data on avian influenza in Hong Kong live poultry markets. A ban on keeping live poultry overnight in these markets reduced virus isolation rates by 84% in chickens (p = 0.006) and 100% (p = 0.01) in minor poultry.     

Campylobacter jejuni in broiler chickens: colonization and humoral immunity following oral vaccination and experimental infection

A formalin inactivated, Campylobacter jejuni whole cell vaccine, either with or without Escherichia coli heat labile toxin (LT) as a mucosal adjuvant, was administered orally to broiler chickens. Three vaccine trials were performed, differing in the number of vaccinations, and time of administration, as well as the inclusion and dose of LT. The overall reductions of C. jejuni colonization in the vaccinated chickens ranged from 16 to 93% compared with non-vaccinated controls. Enhanced levels of anti-C. jejuni secretory IgA antibodies were demonstrated in vaccinated chickens. Vaccination also appeared to induce an anamnestic response to C. jejuni antigens in the 14–33 kDa range, as demonstrated by Western immunoblots. Interestingly, the inclusion of LT in the vaccine regimen did not appear to boost the immunogenicity of the vaccine. These results are encouraging and suggest that future development of successful oral vaccines for the control of enteropathogenic Campylobacter in poultry is feasible.     

Effect of short-term intraocular pressure increase on cat retinal ganglion cell activity

By means of microelectrode recordings receptive field properties and flicker responses of cat retinal ganglion cells were studied during elevated intraocular pressure (IOP). At moderate IOP elevation (perfusion pressure, PP, approx. 50 mm Hg), a slight increase in the maintained activity and the neuronal activation obtained from the receptive field (RF)-center or RF-periphery occurred in some of the neurons. At critical perfusion pressure (PP 30-10 mm Hg), the RF-periphery mechanisms were less sensitive to ischemia than the RF-center mechanisms. The spontaneous activity was completely suppressed at an average PP of 36.6 +/- 9.0 mm Hg, the flicker-evoked responses at 17.7 +/- 9.6 mm Hg. At critical perfusion pressures, the stimulus-response latency increased by 20 ms at stimulation frequencies of 10-20 Hz. The critical flicker frequency was already slightly reduced at a PP of 50 mm Hg and decreased further with a further decrease in PP. The threshold values of the intensity function shifted to higher luminance levels when PP was reduced to less than 40 mm Hg, but the slope remained constant. A close interneuronal correlation was found in simultaneous recordings of pairs of ganglion cells during different levels of increased IOP. This finding indicates that the interneuronal response variability to IOP increase appearing in successively recorded neurons was predominantly caused by experimental factors. The main impairment in retinal neuronal function during increased IOP seems to occur proximal to the receptors but distal to the retinal ganglion cell somata.     

Evidence against gamma-crystallin DNA or RNA sequences in the chicken

A cloned cDNA (pM gamma 1 Crl) encoding about two-thirds of a gamma-crystallin polypeptide from the murine lens was used as a hybridization probe to search for the presence of gamma-crystallin-like RNA or DNA sequences in the chicken. The 15-day-old chicken lens did not contain any RNA sequences homologous to the murine gamma-crystallin cDNA, as judged by Northern blot hybridization. An approximate 2.3 Kbp (kilobase pair) Bam HI fragment from the chicken genome hybridized to the murine gamma-crystallin cDNA in Southern blots. Cloning and sequencing of this genomic fragment, however, did not reveal any homology with gamma- or beta-crystallin sequences. A stretch of 22 dG: dC nucleotides was present in the cloned DNA fragment and possibly this hybridized to the cloned gamma-crystallin cDNA via its dG:dC nucleotide tails introduced during the cloning procedure. These data support those of McDevitt and Croft (1977) indicating that the chicken lens lacks gamma-crystallin and provide evidence against gamma-crystallin mRNA or a gamma-crystallin gene or pseudogene in the chicken. The absence of gamma-crystallin mRNA in the embryonic chicken lens cells makes them potentially useful recipients for investigating the expression of cloned gamma-crystallin genes.     

Biochemical actions of sympathomimetic drugs which overcome cycloheximide-induced amnesia.

Earlier investigations of sympathomimetic drugs overcoming the amnesic action of cycloheximide (CXM) in day-old chickens were extended to biochemical studies in vitro. The effects of amphetamine, norepinephrine, alpha and beta noradrenergic stimulants and receptor blockers on Na+/K+ ATP'ase activity in total homogenate of chicken forebrain were investigated. Norepinephrine and the beta stimulant, isoprenaline significantly stimulated the activity of this enzyme, while the beta blocker, propranolol inhibited activity. Amphetamine, the alpha stimulant, methoxamine and the alpha receptor blocker, piperoxane had no effect on Na/K+ ATP'ase activity in total homogenate. In a purified synaptosomal preparation, both amphetamine (5 X 10(-5) M) and norepinephrine (1 X 10(-4) M) produced a slight stimulation of Na+/K+ ATP'ase activity. A similar concentration of amphetamine (1.12 X 10(-4) M) did not inhibit 14C-leucine uptake or incorporation into protein in the synaptosomal fraction. Nor was it able to alleviate CXM inhibition of 14C-leucine incorporation into synaptosomal protein. The results are interpreted in terms of amphetamine (via release of norepinephrine) norepinephrine and isoprenaline stimulating and maintaining the labile, sodium pump-dependent, phase of memory formation for a sufficient length of time until protein synthesis inhibition by CXM wears off.     

Granuloma disease in flocks of productive layers caused by Tetratrichomonas gallinarum

In 2013, seven outbreaks of granuloma disease occurred in Dutch flocks of productive layers housed on different farms. These outbreaks were characterized by increased mortality and high incidence of granulomas, mainly in caeca (340/408 hens?=?83%) and livers (69/408 hens?=?17%). Mortality started to increase between 21 and 35 weeks of age and reached 3.7% to 11.0% exceeding the breeder's norm in periods ranging from 9 to 48 weeks. Some flocks also showed decreased egg production and/or loss of mean egg weight. All affected flocks were linked to one rearing farm, which therefore seemed to be the source of the disease. However, no signs of disease had been observed at this rearing farm. Sentinel hens placed in one of the affected flocks to determine whether the disease had an infectious nature developed granulomas identical to those seen in the outbreaks. Next, by fulfilling Koch’s postulates it was shown that Tetratrichomonas gallinarum was the aetiological agent of the granuloma disease. The condition was reproduced in mature specified pathogen free White Leghorn hens (GD – Animal Health, Deventer, the Netherlands) by inoculation via both an artificial and a natural route with a well-defined axenic T. gallinarum isolate obtained from one of the affected flocks. Other causes of granuloma disease were excluded.     

Host specificity of avian metapneumoviruses

To date, four subgroups of avian metapneumoviruses have been defined (AMPV-A, B, C and D) based on genetic and antigenic differences. The extent of infection in the three principal species (turkeys, chickens and ducks) by these subgroups is, however, not well defined. Here, a series of controlled and ethically approved experimental infections were performed in specific pathogen-free turkeys, chickens and ducks with each of the four AMPV subgroups. For subgroup C, one strain isolated from turkeys in the USA (turkey AMPV-C) and one isolated from ducks in France (duck AMPV-C) were compared. Globally, these extensive experimental trials demonstrated that AMPV-A, B, turkey C and D were well adapted to Galliformes, especially turkeys; however, chickens showed limited clinical signs and differences in seroconversion and transmission. Notably, chickens did not transmit AMPV-A to contacts and were shown for the first time to be susceptible to AMPV-D. The duck AMPV-C was well adapted to ducks; however, chickens and turkeys seroconverted and were positive by virus isolation. In addition, seroconversion of contact turkeys to duck AMPV-C demonstrated horizontal transmission of this virus in a non-palmiped species under our experimental conditions. Interestingly, in chickens and turkeys, duck AMPV-C isolation was possible despite a lack of detection of viral RNA. Likewise, the turkey AMPV-C virus was well adapted to turkeys yet was also isolated from chickens despite a lack of detection of viral RNA. These results would suggest a selection for viral genetic sequences that differ from the original strain upon adaptation to a ‘non-conventional host’.