Experimental and Field Results Regarding Immunity Induced by a Recombinant Turkey Herpesvirus H5 Vector Vaccine Against H5N1 and Other H5 Highly Pathogenic Avian Influenza Virus Challenges

Vaccination against H5N1 highly pathogenic avian influenza (AI) virus (HPAIV) is one of the possible complementary means available for affected countries to control AI when the disease has become, or with a high risk of becoming, endemic. Efficacy of the vaccination against AI relies essentially, but not exclusively, on the capacity of the vaccine to induce immunity against the targeted virus (which is prone to undergo antigenic variations), as well as its capacity to overcome interference with maternal immunity transmitted by immunized breeding hens to their progeny. This property of the vaccine is a prerequisite for its administration at the hatchery, which assures higher and more reliable vaccine coverage of the populations than vaccination at the farm. A recombinant vector vaccine (Vectormune® AI), based on turkey herpesvirus expressing the hemagglutinin gene of an H5N1 HPAIV as an insert, has been used in several experiments conducted in different research laboratories, as well as in controlled field trials. The results have demonstrated a high degree of homologous and cross protection against different genetic clades of the H5N1 HPAIV. Furthermore, vaccine-induced immunity was not impaired by the presence of passive immunity, but on the contrary, cumulated with it for improved early protection. The demonstrated levels of protection against the different challenge viruses exhibited variations in terms of postchallenge mortality, as well as challenge virus shedding. The data presented here highlight the advantages of this vaccine as a useful and reliable tool to complement biosecurity and sanitary policies for better controlling the disease due to HPAIV of H5 subtypes, when the vaccination is applied as a control measure.

Histopathological and immunohistochemical study of exocrine and endocrine pancreatic lesions in avian influenza A experimentally infected turkeys showing evidence of pancreatic regeneration

In order to investigate the pancreatic lesions caused by the infection with either H7N1 or H7N3 low-pathogenicity avian influenza viruses, 28 experimentally infected turkeys were submitted for histopathology, immunohistochemistry, haematobiochemistry and real-time reverse transcriptase polymerase chain reaction after different days post-infection (DPI). The localization of viral antigen and the measurement of insulin and glucagon expression in the pancreas were assessed to verify the progression from pancreatitis to metabolic disorders, such as diabetes. At the early infection phase (4-7 DPI), a severe acute necrotizing pancreatitis was recognized. During the intermediate phase (8-17 DPI), a mixed acute/chronic change associated with regenerative ductular proliferation was observed. A loss of pancreatic islets was detected in most severe cases and viral antigen was found in the pancreas of 11/28 turkeys (4-10 DPI) with the most severe histological damage. In turkeys euthanized at 39 DPI (late phase), a chronic fibrosing pancreatitis was observed with the reestablishment of both the exocrine and the endocrine pancreas. Insulin and glucagon expression manifested a progressive decrease with subsequent ductular positivity. Haematobiochemistry revealed increased lipasemia in the first week post-infection and hyperglycaemia in the second, with a progressive normalization within 21 DPI. This study allowed the identification of progressive virus-associated exocrine and endocrine pancreatic damage, suggesting that influenza virus might be responsible for metabolic derangements. Moreover, it highlighted a remarkable post-damage hyperplastic and reparative process from a presumptive common exocrine/endocrine precursor. This potential regeneration deserves further investigation for its relevance in a therapeutic perspective to replace lost and non-functional cells in diabetes mellitus.

Spillback transmission of European H1N1 avian-like swine influenza viruses to turkeys: A strain-dependent possibility?

In 1979, an avian influenza virus of the H1N1 subtype began to circulate in European swine herds, rapidly replacing classical swine H1N1 viruses. Spill-back transmissions to turkeys were recorded occasionally, but they might have been underreported due to the asymptomatic nature of the infection and the lack of specific surveillance. In our study, we evaluated the infectivity and transmissibility in turkeys of seven strains of H1N1 avian-like swine viruses isolated from 1979 to 2006, and compared them with their closest progenitor A/duck/Bavaria/1/77 (H1N1), to establish whether the adaptation to pigs has gradually decreased their fitness in turkeys. Our data indicate that the circulation of European H1N1 in pigs might have impaired the possibility of infecting turkeys. Nevertheless, the two swine-origin strains, which showed the ability to replicate and transmit in turkeys, possess typical swine-like genetic traits, not different from the rest of the tested isolates, suggesting replication of avian-like swine H1N1 viruses in turkeys as a strain-dependent polygenic feature.

Phylogenetically distinct equine influenza viruses show different tropism for the swine respiratory tract

Influenza A viruses circulate in a wide range of animals. H3N8 equine influenza virus (EIV) is an avian-origin virus that has established in dogs as canine influenza virus (CIV) and has also been isolated from camels and pigs. Previous work suggests that mutations acquired during EIV evolution might have played a role in CIV emergence. Given the potential role of pigs as a source of human infections, we determined the ability of H3N8 EIVs to replicate in pig cell lines and in respiratory explants. We show that phylogenetically distinct EIVs display different infection phenotypes along the pig respiratory tract, but not in cell lines. Our results suggest that EIV displays a dynamic host range along its evolutionary history, supporting the view that evolutionary processes play important roles in host range and tropism and also underscoring the utility of using explant cultures to study influenza pathogenesis.

Reassortant avian influenza A(H5N1) viruses with H9N2-PB1 gene in poultry, Bangladesh

Bangladesh has reported a high number of outbreaks of highly pathogenic avian influenza (HPAI) (H5N1) in poultry. We identified a natural reassortant HPAI (H5N1) virus containing a H9N2-PB1 gene in poultry in Bangladesh. Our findings highlight the risks for prolonged co-circulation of avian influenza viruses and the need to monitor their evolution.

Susceptibility and intra-species transmission of the H9N2 G1 prototype lineage virus in Japanese quail and turkeys

Avian influenza viruses of the H9N2 subtype have circulated in the poultry population in Asia, Far and Middle East since the mid-1990 s. One of the most widespread lineages established in poultry is the G1 lineage. This lineage has undergone further evolution and reassortment since its first detection in 1997 and G1-like H9N2 viruses still circulate. In this study we have investigated the susceptibility of quail and turkeys to the H9N2 G1-lineage prototype strain (A/quail/Hong Kong/G1/97). Contact transmission experiments were carried out in both avian species. Animals were infected oro-nasally with increasing doses of the virus (10(3)-10(6) EID 50/0.1 ml) and sentinel birds were introduced 4 days post infection (pi) in each experimental group. Quail were more susceptible than turkeys, as they were readily infected with lower challenge doses. Interestingly, infection of turkeys was associated with worse clinical condition. Transmission was detected in both species. Quail infected with a dose less than or equal to 10(4) EID50 transmitted the virus to the sentinels without showing any signs of disease. These findings reinforce the hypothesis that quail may ensure the perpetuation of H9N2 viruses in poultry, acting as a silent reservoir.

Survival rate and prognostic factors in patients with intestinal failure

BACKGROUND

Intestinal failure impairs nutritional status and survival expectance. Though intestinal adaptation and enteral independence may be achieved, artificial nutrition is needed in about half of the patients.

AIMS

This study is aimed at assessing the causes of death, survival rate, enteral independence in time, and factors affecting the clinical outcome in a group of patients with intestinal insufficiency.

PATIENTS

Sixty-eight patients with intestinal insufficiency, due to major intestinal resection in 60 cases (short bowel syndrome) (remnant intestine length 101-150 cm in 31 cases, 50-100 cm in 23 cases, <50 cm in 6 cases), and due to chronic idiopathic pseudo-obstruction in 8 cases, were enrolled and followed-up for (median) 36 months (25th and 75th percentile in 12 and 60 months, respectively). In 60 short bowel syndrome patients, the main conditions that led to intestinal failure were ischemic bowel (28), major surgery complications or severe adhesions (17), radiation enteritis (10), Chron's disease, intestinal tuberculosis, small bowel lymphoma and trauma (others).

METHODS

Seventeen variables age, underlying disorders, length of remnant bowel, type of surgery, hospital stay, type of nutrition (hospital and home) and its variations in time, causes of death, survival rate and time were considered. Statistical analysis was carried out by Mann-Whitney U-test, Pearson chi2, Spearman correlation test, Kaplan-Meyer method and Cox's proportion hazards regression model.

RESULTS

At the time of admission to the hospital, none of the patients had nutritional independence, 54 (79.4%) were on parenteral nutrition and 14 (20.6%) were on enteral nutrition. At the time of discharge, 23 (33.8%) patients showed enteral independence, 39 were on home parenteral nutrition, 3 on enteral nutrition + i.v. feeding, 1 on enteral nutrition, and 2 needed oral supplementation with hydroelectrolyte solutions only. After a median value of 36 months, 30 and 2 patients were on home parenteral nutrition and enteral nutrition + i.v. feeding, respectively, 2 on enteral nutrition, 2 on oral supplementation with hydroelectrolyte solutions, and 26 cases reached enteral independence. A significant relationship was detected between the length of remnant bowel and types of nutrition at both admission (r = 0.38; P = 0.001) and discharge (r = 0.48; P = 0.001), parenteral nutrition being more frequent in patients with very short bowel. Twenty-two patients (32.4%) died (4 from newly occurring malignancies), 40 (58.8%) survived, and 6 (8.8%) were lost to the follow-up. Eleven of 22 patients died from conditions related to intestinal failure (8 cases) and/or home parenteral nutrition complications (3 cases). At 12, 24, 36, 48, 60 and 72 months, survival rates were 95.4, 93.3, 88.1, 78.6, 78.6 and 65.5%, respectively, but it was significantly lower for patients with <50 cm of remnant bowel than those with longer residual intestine (P < 0.05), and in patients who started home parenteral nutrition above the age of 45 years (P < 0.02). Survival rate was higher in patients with enteral independence than those with enteral dependence (P < 0.05). Better survival rates were registered in patients with chronic obstructive intestinal pseudo-obstruction and major surgery complications, whereas ischemic bowel and even more radiation enteritis were associated with a lower survival expectance.

CONCLUSIONS

Actuarial survival rate of patients with intestinal failure quotes 88 and 78% at 3 and 5 years, respectively. It is influenced by the length of remnant intestine, age at the start of home parenteral nutrition, enteral independence and, to some extent at least, by the primary disorder. Enteral independence can be achieved in time by about 40% of the patients with intestinal insufficiency, but for home parenteral nutrition-dependent cases, intravenous feeding can be stopped in less than one out of five patients during a median 3-year period.

Gastric emptying of realistic meals with and without gluten in patients with coeliac disease. Effect of jejunal mucosal recovery

BACKGROUND

Few data are available on disturbed gastric emptying in patients with coeliac disease. The aims of the study were to investigate (a) the presence of delayed gastric emptying: (b) the acute effect on gastric emptying of gliadin; and (c) the effect of jejunal recovery on gastric emptying of meals with or without gluten in such patients.

METHODS

We measured gastric emptying of two meals in 16 patients with coeliac disease; one meal contained gliadin. Results were compared with those obtained in 24 controls. In 12 patients, both measurements were repeated after mucosal recovery. Statistical analysis was performed using the analysis of variance for repeated measurements and Student's t test. Mean +/- 1 s(mean) (standard error of the mean) are shown.

RESULTS

No difference was found in fasting and in maximal antral sections after the two meals. On entry, gastric emptying was significantly (P < 0.001) delayed compared to controls both after the meal containing gluten (326.9 +/- 12.4 min versus controls 213.5 +/- 11.5) and after the gluten-free meal (315.3 +/- 16.7 min). After jejunal recovery, emptying of the meal containing gluten remained unchanged (337 +/- 18.9 min), whereas emptying of the gluten-free meal was significantly shortened (280.6 +/- 10.5 min; P < 0.001).

CONCLUSIONS

In coeliac disease there is an impairment of gastric emptying which is at least partially reversible. This suggests either an immunological disorder or that unabsorbed meal constituents are responsible for an ileal-brake effect.

Liquid stool incontinence with severe urgency: anorectal function and effective biofeedback treatment

The motor and sensory function of the anorectum is well characterised in patients with solid stool incontinence. Fewer data are available in the case of liquid stool incontinence. Anorectal sensorimotor function was studied in 16 patients with liquid stool incontinence and severe urgency (10 with diarrhoea) unresponsive to conventional medical treatment, and in 16 healthy volunteers. The only significant difference found between incontinent patients and controls was a reduction in squeeze duration (p < 0.0001). Fourteen patients were selected to receive biofeedback treatment. Treatment was associated with a substantial improvement in continence in 12 patients and with a significant decrease in urgency (p < 0.05). Bowel frequency was not significantly influenced. Most patients showed a persistent improvement in anal motor function. Functional parameters were not predictive of outcome of treatment; the poor responders showed major psychological problems. In conclusion, an anal motor deficit is often present in disabling liquid stool incontinence. Biofeedback may improve anal continence in 75% of patients.

Pancreatic extracts are necessary for the absorption of elemental and polymeric enteral diets in severe pancreatic insufficiency

Tube feeding nutrition, either elemental or polymeric, is increasingly used in patients with digestive problems. Pancreatic insufficiency is a widely accepted indication for the use of an elemental formula, which requires less residual digestive capacity. To confirm this assumption, we have compared the absorption of elemental and polymeric diets and the effect of exogenous pancreatic enzymes in a patient on long-term total enteral feeding after total pancreatectomy. Malabsorption of both formulas was observed without enzyme supplementation. A marked improvement of fat and nitrogen absorption was obtained when pancreatic enzymes were added to both enteral diets. It is concluded that pancreatic enzymes should always be added to liquid diets in pancreatic insufficiency. No clear advantage is to be anticipated by the use of elemental as compared with polymeric diets.

Impaired colonic motor response to cholinergic stimulation in patients with severe chronic idiopathic (slow transit type) constipation

Chronic idiopathic constipation, especially the slow transit type, is a troubling problem often afflicting young women. The pathophysiological basis for this entity is unknown, although a defective cholinergic innervation has been postulated. We tested the hypothesis that cholinergic colonic innervation is deranged in this condition by studying colonic motor activity after strong cholinergic stimulation with edrophonium chloride in 14 women complaining of slow transit constipation. Unlike healthy subjects, constipated patients showed minimal or no response to edrophonium injection. It is concluded that in slow transit constipation there is an important alteration of colonic cholinergic activity and that edrophonium chloride may represent a useful test drug for colonic pathophysiological investigations.

Effect of nifedipine on mouth-to-cecum transit of liquid meal in normal subjects

Nifedipine has been shown to inhibit small bowel motility and to increase ileal water and electrolyte absorption in animals, but few reports are available in human subjects. The drug has been reported to influence esophageal and colon motility in man, without affecting gastric emptying. We performed a double-blind, controlled, crossover, randomized study to investigate the effect of oral nifedipine 30 mg vs placebo on the orocecal transit time of a lactulose-labeled, liquid caloric meal in nine healthy volunteers, and its correlation with plasma nifedipine concentration. The transit time was measured using the breath hydrogen test. The drug study was preceded by a reproducibility study, which showed a mean variation in transit time of 8.3% (+/- 1%, SE). Nifedipine significantly increased orocecal transit time compared to placebo (nifedipine 131 +/- 16; placebo 104 +/- 14.5 min; P < 0.05). This effect correlated well with plasma nifedipine concentration expressed as area under the curve (r = 0.92, P < 0.004). Nifedipine 30 mg significantly delays orocecal transit of a liquid caloric meal. The small bowel is likely to be the site of action. These findings may afford a rational basis for investigating a possible antidiarrheal role of nifedipine.

[In vitro study of a new pancreatic enzyme with high lipase content in enteric coated microtablets]

In vitro behaviour of the enteric-coating of a new pancreatic enzyme containing preparation in enteric-coated microtablets was evaluated, by incubating at 37 degrees C, under gentle agitation, the preparation under study in buffered gastric (pH 2, 3, 4, 5, 6) and in buffered duodenal juice (pH 3, 4, 5, 6, 7, 8) for 30, 60, 90, 120 minutes. Lipase and chymotripsin activities were measured at each time and pH in the solution and in the undissolved microtablets. The drug under study showed a good enteric-coating, preserving about 100% of the enzyme content, when incubated in buffered gastric juice, up to pH 6, and releasing in the solution, during incubation in buffered duodenal juice, 75% of its enzyme content at pH 7 and 8. Therefore, the pancreatic enzymes contained in this new enteric-coated microtablet preparation are well protected against inactivation from acid and are bioavailable for digestion of alimentary substrates at optimal or near optimal pH in duodenal juice.

Near infrared reflectance measurement of nitrogen faecal losses

Chemical methods of measuring nitrogen in stools are complex, unpleasant, and therefore rarely performed. Recently, near infrared reflectance (NIRA) has been suggested for stool analysis. The aim of this study was to evaluate the possible application of this method in routine faecal nitrogen measurement. Nitrogen concentration and daily output were measured in the stools of 83 patients using NIRA and, for comparison, the Kjeldahl method. Nitrogen concentration and output ranged between 0.4-2.72 g% and 0.45-8.96 g/day respectively. Correlation coefficients (r), of 0.89 and 0.97 were found between the two methods for concentration and output respectively, and similar values were found in patients on enteral nutrition. Repeated measurements from the same stool collection, requiring only a few minutes, allowed homogenisation to be avoided. NIRA seems to be an easy, fast, and reliable alternative to chemical assays of nitrogen measurement in the management of patients with digestive disorders.

Fecal fat concentration in the screening of steatorrhea

We studied if the fecal fat concentration as measured by the near infrared reflectance analysis in a spot sample is an acceptable screening test for malabsorption. This measurement was compared with the more complex fat balance in 120 patients with a suspected malabsorption [53 with chronic pancreatic disorders (CP), 67 with other digestive disorders (nCP)]. The fecal fat concentration proved to be well correlated with steatorrhea in CP (r = 0.86) but not in nCP (r = 0.35). A fat concentration of 9 g% had a sensitivity and a specificity for steatorrhea of 88.8% and of 97.1% in CP, but only of 53.8% and of 94.4% respectively in nCP. The fecal fat concentration was significantly higher in CP than in nCP, even considering patients with steatorrhea only; however, the overlap between the two groups was too high to suggest a clinical usefulness of this test in the differential diagnosis of steatorrheas. It is concluded that the fat concentration in a small sample, easily obtained also in outpatients, is useful in the selection of patients with chronic pancreatitis to submit to a proper fat balance study.