The anamnestic serologic response to vaccination with a canarypox virus-vectored recombinant West Nile virus (WNV) vaccine in horses previously vaccinated with an inactivated WNV vaccine.

A new recombinant West Nile virus (WNV) vaccine has been licensed for use in horses. Prior to the availability of the recombinant vaccine in 2004, the only equine WNV vaccine available on the market had been an inactivated vaccine. Since the recombinant vaccine only expresses selected viral genes, the question could be posed as to whether a single dose of the recombinant vaccine would be effective in producing an anamnestic serologic response in horses previously vaccinated with an inactivated WNV vaccine. In this study we demonstrate that vaccination of horses with a canarypox-vectored recombinant vaccine, under field conditions, results in a marked anamnestic response in horses previously vaccinated with an inactivated WNV vaccine.

Flow cytometric analysis of B cell and T cell subpopulations in specific-pathogen-free chickens infected with infectious bursal disease virus.

Lymphocytes obtained from the blood, spleen, and bursa of normal chickens and of chickens infected with infectious bursal disease virus (IBDV) were analyzed for phenotypic expression of CT4, CT8, and immunoglobulin cell surface markers. Single-cell suspensions were stained with monoclonal antibodies by an indirect immunofluorescent assay, and percent staining was quantitated by flow cytometry. Although an appreciable decline from control levels in the percentage of lymphocytes expressing IgM was detected in the spleen and bursa of infected chickens, the relative proportions of lymphocytes expressing CT4 and CT8 in peripheral blood and spleen remained unchanged following infection. These results suggest that whereas humoral immune depression by IBDV may be associated with lysis of antibody-producing B cells, cellular immune depression is not associated with a detectable change in the proportion of helper or cytotoxic/suppressor subpopulations of T lymphocytes.

Determination of the detection limit of the polymerase chain reaction for chicken infectious anemia virus.

Chicken infectious anemia virus (CIAV) DNA in infected cell cultures and chicken tissues was detected using a polymerase chain reaction (PCR) assay. The complete CIAV genome of several strains was amplified in two segments with two sets of primer pairs. The DNA segments of four CIAV strains and full-length Cux-1 strain DNA were cloned. After amplification, 100 original genome equivalents were detected by Southern hybridization. The sensitivity of the assay was enhanced considerably by performing a reamplification with nested primers. This modification permitted the detection of one molecule of CIAV DNA. Some problems of the assay and its possible application are discussed.

Comparisons of packed cell volumes (PCVs) from so-called chicken anemia agent (CAA; a virus)-free broilers to PCVs from CAA-free specific-pathogen-free leghorns.

Packed cell volumes (PCVs) from 3-, 7-, 14-, 21-, 28-, and 35-day-old clinically healthy chicken anemia agent (CAA)-free and specific-pathogen-free (SPF) leghorn chicks were compared with PCVs from age-matched clinically healthy CAA-free broiler chicks. The PCVs of the SPF chicks regressed significantly (F = 20.6, df = 2/3, P < 0.025) on age in a linear fashion. The PCVs of the broiler chicks regressed significantly (F = 9.56, df = 2/3, P < 0.05) on age in a cubic parabola. The mean PCVs of the broiler chicks were significantly (P < 0.05) higher than PCVs of SPF chicks at every tested time interval. Results indicate that PCV values are higher in broiler chicks than in SPF leghorn chicks, and that PCVs increase as chicks age. Clinicians, diagnosticians, and investigators who intend to work with chicken blood must be aware of these differences.

Marek's disease virus isolates with unusual tropism and virulence for ocular tissues: clinical findings, challenge studies and pathological features.

Outbreaks of Marek's disease (MD) were diagnosed in two flocks from the same company. Clinical signs, mainly blindness (>90%), but also depression, mild paralysis, and 11 to 12% mortality by 20 weeks of age were observed. MD virus, serotype 1 was isolated. The isolates were designated NC-1 (flock 1) and NC-2 (flock 2). Challenge experiments were conducted with these isolates and with two reference MD virus strains (JM/102W and Md5) in unvaccinated, turkey herpesvirus- (HVT) vaccinated and bivalent- (HVT and SB-1) vaccinated chickens. Blindness, gross ocular lesions and tumour formation were observed in a high proportion of all groups challenged with NC-1 and NC-2 when compared with chickens challenged with JM/102W and Md5. In chickens challenged with isolates NC-1 and NC-2, corneal changes included oedema, midstromal cellular infiltration consisting of macrophages, lymphocytes, plasma cells and lesser numbers of heterophils, collagen degeneration and keratic precipitates consisting primarily of macrophages covering the central endothelium. Eosinophilic intranuclear inclusion bodies were present in mononuclear cells infiltrating the cornea. Changes in the uveal tract consisted of inflammatory cell infiltrates similar to those present in the cornea. Retinal lesions included disruption of the retinal pigmented epithelium, inflammatory cell infiltration in the subretinal space, photoreceptor degeneration and in severely affected eyes, necrosis of retinal cellular elements. Pecten changes consisted of necrosis and mononuclear cell infiltration. Intranuclear inclusion bodies were abundantly present in cells of the retina's ganglion and inner nuclear cell layers. The unusual clinical manifestation of MD, the unusual tropism and virulence of NC-1 and NC-2 for ocular tissues and the incomplete protection afforded by conventional vaccination suggest that these isolates may be new pathotypes.

Production and Partial Characterization of Stylet Exudate from Adult Females of Meloidogyne incognita.

Adult females of Meloidogyne incognita were excised from tomato roots and incubated in 0.04 M phosphate buffered saline, pH 7.4 for 18-72 hours to allow accumulation of stylet exudate. Twenty-four percent of the females produced exudate during the initial 18-hour incubation period; 70% of those females producing exudate initially produced additional exudate during the subsequent 54-hour incubation period. Analysis of exudate by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of at least nine major protein bands. Differential staining with silver and Coomassie Brilliant Blue G-250 stains indicated that three of the bands were glycoproteins. Upon acid hydrolysis, 14 amino acids were detected in the stylet exudate. The basic amino acids lysine, histidine, and arginine comprised 21.8% of the total amino acids detected. No peroxidase activity was detected in the stylet exudates. Data presented extend and generally confirm prior work on the chemical composition of stylet exudate.

Experimental transmission of the Texas strain of Hepatozoon canis.

Nine dogs were fed Hepatozoon canis-exposed Rhipicephalus sanguineus ticks; 6 showed clinical signs suggestive of canine hepatozoonosis, and the parasite was found in sections of muscle tissue from 2 of the dogs. Schizont-like cysts were found in the skeletal muscle of both infected dogs as were gametocytes in the circulating leucocytes. Periosteal new-bone lesions were seen in 1 dog. Attempts to infect a raccoon, 3 cats, 6 laboratory mice, and tick- or canine-cells in vitro, failed.