Evaluation of vaccination against infectious laryngotracheitis (ILT) with recombinant herpesvirus of turkey (rHVT-LT) and chicken embryo origin (CEO) vaccines applied alone or in combination.

The chicken embryo origin (CEO) infectious laryngotracheitis (ILT) live attenuated vaccines, although capable of protecting against disease and reducing challenge virus replication, can regain virulence. Recombinant ILT vaccines do not regain virulence but are partially successful at blocking challenge virus replication. The objective of this study was to evaluate the effect of rHVT-LT vaccination on CEO replication and how this vaccination strategy enhances protection and limits challenge virus transmission to naïve contact chickens. The rHVT-LT vaccine was administered at 1 day of age subcutaneously and the CEO vaccine was administered at 6 weeks of age via eye-drop or drinking water. CEO vaccine replication post vaccination, challenge virus replication and transmission post challenge were evaluated. After vaccination, only the group that received the CEO via eye-drop developed transient conjunctivitis. A significant decrease in CEO replication was detected for the rHVT-LT + CEO groups as compared to groups that received CEO alone. After challenge, reduction in clinical signs and challenge virus replication were observed in all vaccinated groups. However, among the vaccinated groups, the rHVT-LT group presented higher clinical signs and challenge virus replication. Transmission of the challenge virus to naïve contact chickens was only observed in the rHVT-LT vaccinated group of chickens. Overall, this study found that priming with rHVT-LT reduced CEO virus replication and the addition of a CEO vaccination provided a more robust protection than rHVT alone. Therefore, rHVT-LT + CEO vaccination strategy constitutes an alternative approach to gain better control of the disease.

Early infection with Marek's disease virus can jeopardize protection conferred by laryngotracheitis vaccines: a method to study MDV-induced immunosuppression.

Marek's disease virus (MDV) is a herpesvirus that induces lymphomas and immunosuppression in chickens. MDV-induced immunosuppression (MDV-IS) is divided into two phases: early-MDV-IS occurring mainly in chickens lacking maternal antibodies (MAb) against MDV and associated with lymphoid organ atrophy; and late-MDV-IS occurring once MDV enters latency and during tumour development. Our objectives were to document the impact of late-MDV-IS on commercial poultry (meat-type chickens bearing MAb against MDV and that were vaccinated or unvaccinated against MD) and to optimize a model to study late-MDV-IS under laboratory conditions. The impact of late-MDV-IS was evaluated by assessing the effect of early infection (day of age) with a very virulent plus MDV (vv+MDV) on the efficacy of chicken-embryo-origin (CEO) infectious laryngotracheitis (ILT) virus vaccine against ILT challenge. The CEO ILT vaccine was administered in water at 14 days of age and ILT virus (ILTV) challenge was done intratracheally at 30 days of age. Development of ILT was monitored by daily evaluation of clinical signs, development of gross and histological lesions in trachea, and quantification of ILTV transcripts in trachea. Infection with vv+MDV strain 648A resulted in total abrogation of protection conferred by the CEO vaccine against ILTV challenge even in chickens vaccinated at 1 day of age with either HVT, HVT+SB-1, or CVI988. Chickens exposed to vv+MDV prior to vaccination with CEO ILTV vaccine had similar (P < 0.05) clinical scores, gross lesions, histopathologic lesion scores, and load of ILTV transcripts in trachea after ILTV challenge, as chickens that were not vaccinated with CEO ILTV vaccine.

Does positioning affect tracheal aspiration of gastric content in ventilated infants?

OBJECTIVES: Gastroesophageal reflux and aspiration can occur in premature infants who are supported with mechanical ventilation. The relation between physical positioning and gastric aspiration in ventilated infants has not been studied. Pepsin measured in tracheal aspirate (TA) emerged as a specific marker for aspiration. The objective of our study was to assess pepsin in TA of ventilated infants at 2 different positions: supine and right lateral. METHODS: We conducted a randomized controlled trial on premature infants who were enterally fed and supported with mechanical ventilation. Patients were randomized into intervention and control groups. In the intervention group, infants were placed supine for 6 hours before a sample of TA was obtained. A second sample was collected 6 hours later while lying in the right lateral position. In the control group, the 2 samples of TA were obtained while infants remained in the supine position during the entire study time. Pepsin in TA was measured while blinded to the group assignment. RESULTS: A total of 34 patients were enrolled and randomized to intervention (n = 17) and control (n = 17) groups. Gestational age was 32.7 ± 2.7 weeks, and birth weight was 1617 ± 526 g; both groups had similar demographic and clinical characteristics. Pepsin concentration did not differ between groups at baseline. In the intervention group, pepsin concentration significantly declined from 13 ng/mL (interquartile range [IQR] 11.9-38.7) to 10 ng/mL (IQR 7-12; P < 0.001), whereas it did not change in the control group (P = 0.42). CONCLUSIONS: The right lateral positioning is associated with decreased TA pepsin. The implications of the present study on hospital practice and clinical outcomes need further investigations.

Multidisciplinary quality improvement initiative to reduce ventilator-associated tracheobronchitis in the PICU.

OBJECTIVE: To test the hypothesis that successful implementation of a care bundle designed to prevent nosocomial airway infection will be associated with decreased incidence of ventilator-associated tracheobronchitis. DESIGN: Prospective pre- and post interventional. SETTING: PICU at an academic medical center PATIENTS: : All patients admitted to the PICU who received invasive mechanical ventilation for greater than or equal to 48 hours between March 1, 2009, and December 31, 2011. INTERVENTION: Multidisciplinary, unit wide implementation of an evidence-based care bundle to prevent ventilator-associated airway infection. MEASUREMENTS AND MAIN RESULTS: There were 725 patients included in the analysis (338 patients preintervention and 387 patients postintervention). Baseline ventilator-associated tracheobronchitis rate in the preintervention period was 3.9 cases per 1,000 ventilator days compared with 1.8 cases per 1,000 ventilator days postintervention (p = 0.04, Fisher exact test). Compared with patients without ventilator-associated tracheobronchitis or ventilator-associated pneumonia, patients with ventilator-associated tracheobronchitis had fewer ventilator-free days in 28 days (4.9 vs 22; p < 0.0001, Mann-Whitney U test) and fewer ICU-free days in 28 days (0.5 vs 19; p < 0.0001, Mann-Whitney U test). These relationships remained significant after adjusting for covariates by multivariable linear regression. CONCLUSIONS: Successful implementation of a care bundle to prevent ventilator-associated infection was associated with decreased incidence of ventilator-associated tracheobronchitis. Development of ventilator-associated tracheobronchitis was independently associated with adverse outcomes in our cohort of pediatric ICU patients.

[The potential of prophylaxis and optimization of the treatment of rhinosinusitis in the children presenting with stenosing laryngotracheitis].

The objective of the present work was to estimate the clinical, prophylactic, and microbiological effectiveness of fusafungine applied for the treatment of acute rhinosinusitis (ARS) in the children that develops as a consequence of acute stenosing laryngotracheitis. The study included 61 children presenting with ARS and concomitant acute stenosing laryngotracheitis (ASLT) that were treated with fusafungine (Bioparox). Both tolerance and safety of this preparation were evaluated. Fusaferine was prescribed after reduction of pharyngeal stenosis. The children were divided into two groups. Group 1 was comprised of the patients with the respiratory symptoms and rhinosinusitis (n = 36), group 2 consisted of the children with the respiratory symptoms in the absence of rhinosinusitis (n = 25). Subgroups of the children treated with fusafungine and without it were distinguished to estimate the clinical, prophylactic, and microbiological effectiveness of fusafungide. Within the first days after hospitalization, 59% of the children with diagnosis ASLT developed bilateral rhinosinusitis, in all probability of viral etiology. Fusafungine produced the clinically apparent effect in the patients with ASLT regardless of the presence of ARS. Specifically, this preparation decreased the degree of hypertrophy of pharyngeal tonsils three times faster than standard therapy; moreover, it reduced the requirement for systemic antibiotics by 1.9 times. The treatment with fusaferine prevented the development of acute bilateral rhinosinusitis in the children with ASLT and promoted compete decontamination of the nasopharynx from M. catarrhalis, Str. pneumonia, Str. pyogenes, H. influenza, Cor. s the nasopharynx pecies, E. faecalis, and C. albicans. The frequency of adverse reactions of organoleptic character was estimated at 16.6%.

Commercial Vaccines and Vaccination Strategies Against Infectious Laryngotracheitis: What We Have Learned and Knowledge Gaps That Remain.

Infectious laryngotracheitis (ILT) is an upper respiratory disease of chickens, pheasants, and peafowl caused by the alphaherpesvirus Gallid alpha herpesvirus 1 (GaHV-1), commonly known as infectious laryngotracheitis virus. ILT is an acute respiratory disease characterized by clinical signs of conjunctivitis, nasal discharge, dyspnea, and lethargy. In severe forms of the disease, hemorrhagic tracheitis together with gasping, coughing, and expectoration of bloody mucus are common. The morbidity and mortality rates of the disease vary depending on the virulence of the strain circulating, the level of virus circulating in the field, and the presence of other respiratory infections. Since the identification of the disease in the 1920s, ILT continues to affect the poultry industry negatively across the globe. The disease is primarily controlled by a combination of biosecurity and vaccination. The first commercial vaccines, introduced in the late 1950s and early 1960s, were the chicken embryo origin live attenuated vaccines. The tissue culture origin vaccine was introduced in late 1970s. Recombinant viral vector ILT vaccines were first introduced in the United States in the 2000s, and now they are being used worldwide, alone or in combination with live attenuated vaccines. This review article provides a synopsis of what we have learned about vaccines and vaccination strategies used around the world and addresses knowledge gaps about the virus and host interactions that remain unknown.

Estudio recapitulativo. Vacunas comerciales y estrategias de vacunación contra la laringotraqueitis infecciosa: lo que se ha aprendido y los vacíos de conocimiento que persisten La laringotraqueítis infecciosa (ILT, por sus siglas en inglés) es una enfermedad del tracto respiratorio superior de pollos, faisanes y pavos reales, causada por el alfaherpesvirus herpesvirus del pollo 1 (GaHV-1), conocido comúnmente como virus de la laringotraqueitis infecciosa. La laringotraqueitis infecciosa es una enfermedad respiratoria aguda caracterizada por signos clínicos de conjuntivitis, secreción nasal, disnea y letargo. En las formas severas de la enfermedad, son comunes la traqueítis hemorrágica junto con jadeo, tos y expectoración de moco con sangre. Las tasas de morbilidad y mortalidad de la enfermedad varían según la virulencia de la cepa que está circulando, el nivel de virus que circula en el campo y la presencia de otras infecciones respiratorias. Desde la identificación de la enfermedad en la década de los 1920's, la laringotraqueitis infecciosa continúa afectando negativamente a la industria avícola en todo el mundo. La enfermedad se controla principalmente mediante una combinación de bioseguridad y vacunación. Las primeras vacunas comerciales introducidas a fines de los años cincuenta y principios de los sesenta, fueron las vacunas atenuadas vivas con origen en embrión de pollo. La vacuna con origen en cultivo de células se introdujo a fines de los años 70 en los Estados Unidos. Las vacunas contra la laringotraqueitis infecciosa desarrolladas con vectores virales recombinantes se introdujeron por primera vez en los Estados Unidos en la década de 2000's y ahora se están utilizando en todo el mundo, solas o en combinación con vacunas atenuadas vivas. Este artículo recapitulativo proporciona una sinopsis de lo que se ha aprendido sobre las vacunas contra la laringotraqueitis infecciosa, las estrategias de vacunación utilizadas en todo el mundo y aborda los vacíos en el conocimiento sobre el virus y las interacciones con el huésped que siguen siendo desconocidas.

[Suppression effect of different stage antigens of Schistosoma japonicum on airway inflammation in a murine model of asthma].

OBJECTIVE: To investigate the effect of antigens of different stage Schistosoma japonicum on airway inflammation in a murine model of asthma. METHODS: 48 female BALB/c mice were randomly divided into eight groups. Mice in group A were given normal saline of equal volume as control. Group B was asthma model which was established by intraperitoneal and intranasal challenge with OVA. Mice in groups C, D and E were immunized with soluble egg antigen (SEA), soluble male worm antigen (SWA), and schistosomulum antigen (SSA) respectively 4 times in a week interval, followed by OVA sensitization as in group B 1 week after the final immunization. Mice in groups F, G, and H were immunized with SEA, SWA, and SSA respectively but sensitized and challenged with saline instead of OVA. 48 hours after asthma was induced, the mice were sacrificed. Leukocytes and eosinophils were counted in bronchoalveolar lavage fluid (BALF). The level of IL-5, IL-10 and IFN-gamma in BALF was detected. Pathologic changes in lung tissues were observed. RESULTS: Inflammation cells, especially eosinophils, appeared in airways of mice in groups B, C, D and E, but with much less number in groups C, D and E. No inflammation cells were seen in airways of group A mice. The number of leukocytes, eosinophils and level of IL-5 in BALF of group B [(98.4 +/- 16.1) x 10(4)/ml, (17.6 +/- 4.3) x 10(4)/ml, (197.9 +/- 36.5) pg/ml respectively] were significantly higher than those of group A [(8.2 +/- 1.1) x 10(4)/ml, (0.02 +/- 0.01) x 10(4)/ ml, (12.3 +/- 7.4) pg/ml], however the levels of IL-10 and IFN-gamma were significantly lower than that of group A (P < 0.05). The number of leukocytes, especially eosinophils, in BALF of groups C, D and E was significantly lower than that of group B. The level of IL-5 in BALF of groups C, D and E was significantly reduced, while that of IL-10 and IFN-gamma in BALF of the 3 groups was significantly higher than group B (P < 0.05). CONCLUSIONS: The immunization with S. japonicum antigens can effectively modulate the level of cytokines and inhibit the eosinophil infiltration and airway inflammation in asthmatic mice.

Enhanced infection of avian influenza virus H9N2 with infectious laryngeotracheitis vaccination in chickens.

Avian influenza and infectious laryngeotracheitis viruses are common causes of respiratory diseases in chickens with economical importance worldwide. In this study, we investigated the effect of experimental co-infection of avian influenza virus-H9N2 (AIV-H9N2) with infectious laryngeotracheitis virus (ILTV) live-attenuated vaccine (LAR-VAC®) on chickens. Four experimental groups were included in this study: negative control group, AIV-H9N2 group, AIV-H9N2+LAR-VAC® group, and LAR-VAC® group. AIV-H9N2 was inoculated intranasally to challenged groups at 35 days of age. On the same day, LAR-VAC® was ocularly administered to vaccinated groups. Chickens were observed for clinical signs, changes in body weight and mortality rates. Tissue samples, sera, tracheal and cloacal swabs, and blood were also collected at 3, 6, 9 and 12 days post-infection (PI). A significant increase in clinical signs and mortality rates were observed in the AIV-H9N2 + LAR-VAC® group. Moreover, chickens coinfected with AIV-H9N2 and LAR-VAC® showed a significant decrease in body weight and lymphoid organs indices. The tracheal gross and histopathological lesions and the shedding titer and period of AIV-H9N2 were significantly higher in AIV-H9N2 + LAR-VAC® group when compared to other groups. Furthermore, AIV-H9N2 infection leads to humoral and cellular immunosuppression as shown by a significant decrease in the CD4+/CD8+ ratio and antibody responses to ILTV and a significant increase in H/L ratio. In conclusion, this is the first report of co-infection of AIV-H9N2 and ILTV vaccine in chickens, which leads to increased pathogenicity, pathological lesions, and AIV-H9N2 shedding titer and period, which can lead to severe economic losses due to poor weight gain and mortality.

Continuous versus intermittent endotracheal cuff pressure control for the prevention of ventilator-associated respiratory infections in Vietnam: study protocol for a randomised controlled trial.

BACKGROUND: Ventilator-associated respiratory infection (VARI) comprises ventilator-associated pneumonia (VAP) and ventilator-associated tracheobronchitis (VAT). Although their diagnostic criteria vary, together these are the most common hospital-acquired infections in intensive care units (ICUs) worldwide, responsible for a large proportion of antibiotic use within ICUs. Evidence-based strategies for the prevention of VARI in resource-limited settings are lacking. Preventing the leakage of oropharyngeal secretions into the lung using continuous endotracheal cuff pressure control is a promising strategy. The aim of this study is to investigate the efficacy of automated, continuous endotracheal cuff pressure control in preventing the development of VARI and reducing antibiotic use in ICUs in Vietnam. METHODS/DESIGN: This is an open-label randomised controlled multicentre trial. We will enrol 600 adult patients intubated for ≤ 24 h at the time of enrolment. Eligible patients will be stratified according to admission diagnosis (180 tetanus, 420 non-tetanus) and site and will be randomised in a 1:1 ratio to receive either (1) automated, continuous control of endotracheal cuff pressure or (2) intermittent measurement and control of endotracheal cuff pressure using a manual cuff pressure meter. The primary outcome is the occurrence of VARI, defined as either VAP or VAT during the ICU admission up to a maximum of 90 days after randomisation. Patients in both groups who are at risk for VARI will receive a standardised battery of investigations if their treating physician feels a new infection has occurred, the results of which will be used by an endpoint review committee, blinded to the allocated arm and independent of patient care, to determine the primary outcome. All enrolled patients will be followed for mortality and endotracheal tube cuff-related complications at 28 days and 90 days after randomisation. Other secondary outcomes include antibiotic use; days ventilated, in ICU and in hospital; inpatient mortality; costs of antibiotics in ICU; duration of ICU stay; and duration of hospital stay. DISCUSSION: This study will provide high-quality evidence concerning the use of continuous endotracheal cuff pressure control as a method to reduce VARI, antibiotic use and hospitalisation costs and to shorten stay. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02966392 . Registered on November 9, 2016. Protocol version: 2.0; issue date March 3, 2017.

[Role of closed aspiration systems in the prevention of lower respiratory tract infections during artificial ventilation].

Two large intensive care centers performed a prospective controlled, randomized study evaluating the efficiency of closed aspiration systems in the prevention of lower respiratory tract infections during sustained artificial ventilation. Analysis of the results of the study has ascertained that the closed aspiration systems make it possible to attenuate a colonization process and further lower respiratory tract infection, by statistically significantly reducing the risk of tracheobronchitis and pneumonia.

Preventive Effect of Cow's Milk Fermented with Lactobacillus paracasei CBA L74 on Common Infectious Diseases in Children: A Multicenter Randomized Controlled Trial.

Background: Fermented foods have been proposed to prevent common infectious diseases (CIDs) in children attending day care or preschool. OBJECTIVES: To investigate the efficacy of dietary supplementation with cow's skim milk fermented with the probiotic Lactobacillus paracasei CBA L74 in reducing CIDs in children attending day care or preschool. Methods: Multicenter, randomized, double-blind, placebo-controlled trial on healthy children (aged 12-48 months) consuming daily 7 grams of cow's skim milk fermented with L. paracasei CBA L74 (group A), or placebo (maltodextrins group B) attending day care or preschool during the winter season. The main outcome was the proportion of children who experienced ≥1 episode of CID during a 3-month follow-up. Fecal biomarkers of innate (α- and ß-defensins, cathelicidin) and acquired immunity (secretory IgA) were also monitored. Results: A total of 126 children (71 males, 56%) with a mean (SD) age of 33 (9) months completed the study, 66 in group A and 60 in group B. At intention to treat analysis, the proportion of children presenting ≥1 CID was 60% in group A vs. 83% in group B, corresponding to an absolute risk difference (ARD) of -23% (95% CI: -37% to -9%, p < 0.01). At per-protocol-analysis (PPA), the proportion of children presenting ≥1 CID was 18% in group A vs. 40% in group B, corresponding to an absolute risk difference (ARD) of -22% (95% CI: -37% to -6%, p < 0.01). PPA showed that the proportion of children presenting ≥1 acute gastroenteritis (AGE) was significantly lower in group A (18% vs. 40%, p < 0.05). The ARD for the occurrence of ≥1 AGE was -22% (95% CI: -37% to -6%, p < 0.01) in group A. Similar findings were obtained at PPA regarding the proportion of children presenting ≥1 upper respiratory tract infection (URTI), which was significantly lower in group A (51% vs. 74%, p < 0.05), corresponding to an ARD of -23% (95% CI: -40% to -7%, p < 0.01). Significant changes in innate and acquired immunity biomarkers were observed only in subjects in group A. Conclusions: Dietary supplementation with cow's skim milk fermented with L. paracasei CBA L74 is an efficient strategy in preventing CIDs in children.

[Investigation of the risk factors and prevention of nosocomial tracheobronchitis in elderly patients on mechanical ventilation in surgical intensive care unit].

OBJECTIVE: To investigate the incidence, the risk factors and the outcome of nosocomial tracheobronchitis (NTB) in patients age over 65 years of age receiving mechanical ventilation (MV). METHODS: Using prospective cohort study to collect and analyse the clinical information of elderly patients who received mechanical ventilation in surgical intensive care unit (ICU) of Zhongshan Hospital, from November 2002 to July 2004. Patients with first episodes of NTB were compared with those without NTB by univariate analysis and logistic regression. RESULTS: There were 35 elderly patients diagnosed as having NTB (53.0%). The differences in serum albumin, nasal feeding, the length of ICU stay, the duration of MV days, the acute physiology and chronic health evaluation II (APACHE II) score and the kinds of the antibiotic used between patients with NTB and without NTB were significant. The results of the univariate analysis showed that nasal feeding, low serum albumin, the duration of the MV>4 days, the length of ICU stay >9 days, the kinds of antibiotics used and the APACHE II score higher than 9 were the risk factors of NTB. However the logistic regression suggested that nasal feeding, MV days >4 days, nasal feeding and the kinds of the antibiotics used >2 are the independent risk factors of NTB. CONCLUSION: There is high incidence of NTB in ventilated patients in surgical ICU. Low albumin level, nasal feeding, prolonged MV and ICU stay days, high APACH II score and administration of too much antibiotics are the important risk factors of NTB.

Comparison of open dilatational tracheostomy with conventional pediatric tracheostomy in a growing animal model.

OBJECTIVES: To compare the tracheal changes after applying a new open dilatational tracheostomy (ODT) technique with those from a conventional open tracheostomy (COT) with vertical cartilage incision in a growing animal model. STUDY DESIGN: Prospective, experimental investigation in a rabbit model. MATERIALS AND METHODS: Thirteen New Zealand white rabbits as a pediatric model were divided into three groups: six rabbits had COT (n = 6), another six underwent an ODT (n = 6), and one rabbit acted as a control. Each rabbit underwent tracheostomy by assigned procedures on the first day. On day 8, they were decannulated. On day 15, their tracheas were harvested. We examined the gross findings and histologic changes of each tracheal segment at the stomal level. In addition, we analyzed three parameters: the quotient of the stomal and nonstomal segment in sagittal diameter, coronal diameter, and cross-sectional area. RESULTS: The framework of cartilages at the stomal level were more distorted in the COT group. Histologic examination also showed buckling of the anterior tracheal wall, loss of cartilage, infiltration by many polymorphonuclear neutrophils, and the marked ingrowth of fibrous tissue in the COT group. Sagittal and coronal diameters and cross-sectional areas were significantly affected more severely after a COT than after an ODT. CONCLUSION: Our new modification of percutaneous dilatational tracheostomy, named "open dilatational tracheostomy," was successfully applied to a small, growing animal model and showed more favorable and consistent healing of trachea compared with COT. Therefore, the authors' new tracheostomy procedure could be applied to children who require short-term tracheostomy at any age in clinical settings.

Control of turkey Alcaligenes rhinotracheitis in Utah with a live vaccine.

During the 1980 growing season in the Sanpete Valley of Utah, about half of the 250 to 300 flocks of turkeys were vaccinated with an oral vaccine against alcaligenes rhinotracheitis (ART). The vaccine consisted of a temperature-sensitive mutant of Alcaligenes faecalis. Most vaccinated birds developed serum antibodies. No outbreaks of ART occurred in vaccinated flocks, although some outbreaks occurred in unvaccinated flocks. During 1979, when on flocks were vaccinated, over 90% of the flocks experienced outbreaks of ART during late summer.

Effect of route of vaccination on the prevention of infectious laryngotracheitis in commercial egg-laying chickens.

Commercial egg-laying chickens were vaccinated for infectious laryngotracheitis (ILT) with one of five commercially available vaccines (designated A, B, C, D, and E) on five separate farms by either eyedrop (e), spray (s), or double dose in the water (w) method. Groups were identified by the vaccine designation and the method of vaccination. Birds from the test groups were transferred to an isolation facility and challenged intratracheally 3 wk after vaccination. The remaining birds were given a second vaccination with the original chicken embryo origin vaccine by spray or a chicken embryo origin vaccine if the first vaccine was of tissue culture origin. After challenge, birds were monitored for clinical signs. Those surviving were euthanatized on day 6 postchallenge, and tissues and blood were collected for histopathology, virus isolation, and serology. On the basis of histopathology and enzyme-linked immunosorbent assay (ELISA) results, after one vaccination, all chickens given vaccines by eyedrop were provided better protection than nonvaccinated controls (CTLs). Birds in groups Bs and Ds had lower microscopic lesion scores whereas only birds given Bs had higher ELISA titers than CTLs. Birds in groups As and Cs and groups Bw birds taken from the rear of the barn (r) had microscopic lesion scores that were no different from those of CTLs. These same birds in addition to vaccine Ds had ELISA titers no different from those of CTLs. Of all vaccines, only A given by eyedrop or spray produced higher virus isolation titers than those of CTLs. The remainder of the vaccines produced virus isolation titers that were no different from those of CTLs. After two vaccinations, all groups had lower microscopic lesion scores than CTLs. Only Bw birds from the middle of the barn Bs, EeDs, and AsAs had virus isolation results that were higher than those of CTLs. Only groups BwrBs, CsCs, and DsDs had ELISA titers no different from those of controls. These results suggest that a priming vaccination followed by a booster dose offers better protection against ILT than a single vaccination alone. Vaccine application by eyedrop provides more uniform protection if only one vaccination is given, whereas spray vaccination may serve as an alternative method of vaccination for birds receiving two doses of vaccine.

Intranasal vaccination of dogs with liver avirulent Bordetella bronchiseptica: correlation of serum agglutination titer and the formation of secretory IgA with protection against experimentally induced infectious tracheobronchitis.

Dogs inoculated intranasally with a live avirulent Bordetella bronchiseptica vaccine were monitored for the development of resistance to experimentally induced infectious tracheobronchitis (canine cough). Dogs were challenge exposed with a virulent strains of B bronchiseptica at various times after they were vaccinated. Clinical protection was detectable as early as 48 hours. At postvaccination days 4, 5, and 14, 56%, 83%, and 95% protection was observed. Humoral immunoglobulin (Ig) titers ranged from 1:8.6 on day 0 to 1:147 on postvaccination day 21. In the monitoring of B bronchiseptica-specific secretory IgA by indirect immunofluorescence, titers appeared as early as day 4 after vaccination. The IgA titers ranged from 1:16 on day 4 to 1: 1,024 on day 21. The appearance of IgA titers correlated with the development of resistance to clinical infection.

Antibody response to an inactivated vaccine for rhinotracheitis, caliciviral disease, and panleukopenia in nondomestic felids.

The efficacy of an inactivated vaccine for the prevention of feline viral rhinotracheitis (FVR), feline caliciviral disease (FCVD), and feline panleukopenia (FPL) was tested in 27 nondomestic adult felids from 7 species. The vaccine was given IM at the standard domestic cat dose in 19 animals and double this dose in 8 others. The animals were vaccinated either 1, 2, or 3 times. Serum-neutralization (SN) antibodies to FVR (mean SN titer, 23) developed in all 15 animals that were previously seronegative, and SN antibodies to FCVD (mean SN titer, 11) developed in 19 of 21 animals that were previously seronegative. There was no significant increase of SN antibody titers by doubling the vaccine dose or by administering a 3rd vaccination. The optimal response could be obtained by using the domestic cat vaccination protocol of a single dose given twice, 4 weeks apart. The critical evaluation of the SN antibody titer for FPL was complicated by preexisting titers to FPL from previous vaccinations, but in 23 animals the titers became higher, whereas they remained unchanged in only 4 animals. The persistence of the SN titers was evaluated 7 to 9 months later and found to be satisfactory for FVR (mean SN titer, 18) FCVD (mean SN titers, 43) and FPL (mean SN titer, 517). Enhanced persistence of titer could not be demonstrated by doubling the dose or administering a 3rd vaccination.

Immunogenicity and safety of an inactivated vaccine for the prevention of rhinotracheitis, caliciviral disease, and panleukopenia in cats.

An inactivated vaccine for the prevention of feline viral rhinotracheitis (FVR), caliciviral disease, and panleukopenia has been developed. The efficacy of this vaccine for protection against FVR and caliciviral disease was assessed by vaccination of 41 cats and challenge of immunity with rrither FVR virus or feline calicivirus (FCV), strain 225. All vaccinates cats developed serum neutralizing (SN) antibody (mean SN50 1:45.5) to FVR virus, and 95% developed antibody (mean SN50 1:8.1) to FCV, strain 255. Following FVR challenge, the mean cumulative score of clinical signs was 1.1 for vaccinated cats versus 22.2 for controls. Following FCV challenge, the mean scores were 2.7 for vaccinated and 17.5 for controls. Immunogenicity of the panleukopenia fraction was demonstrated by the development of neutralizing antibody titers > 1:8 in all 21 vaccinates that were tested.