Establishing bioequivalence of veterinary premixes (Type A medicated articles)

a) Key issues concerning Premix (Type A medicated articles) Bioequivalence evaluations: 1) This is a complex issue concerning both route of administration and formulation. 2) If the animal is not at the bunk/trough, the animal is not self-administering (eating medicated feed), thus there can be no drug absorption. b) Differing opinions among scientists and regulatory authorities/expert bodies regarding: 1) No harmonization on how to design, conduct, and interpret in vivo studies. 2) Applicability of biowaivers to Type A (premix) products. 3) Why are topdress and complete feed considered differently? Are they different formulations or different routes of administration? 4) Single dose vs. multi-dose studies. 5) What is the final formulation? c) What are the next steps: 1) Harmonize current bioequivalence guidelines through the VICH process. 2) Determine the applicability/non-applicability of the Biopharmaceutical Classification System (BCS). 3) Establish the Total Mixed Ration (i.e. formulation) effects. 4) Define the test subject (individual, pen, etc.).     

Experimental infection in pigs with encephalomyocarditis virus

Non-suppurative myocarditis in pigs that were experimentally infected with encephalomyocarditis (EMC) virus is reported. Two of the four pigs that were infected with the virus died suddenly from myocardial failure, and all four had gross and microscopic changes consistent with EMC infection. This confirms the pathogenic potential of some strains of EMC virus for young pigs.     

Experimental infections with fowl pox in chickens

Seven groups of chickens were challenged with a field isolate of fowl pox virus at 18 weeks old. The birds in the groups that had been vaccinated 3 weeks previously with fowl pox vaccinates showed no signs of disease. Birds which had not been vaccinated against fowl pox developed upper respiratory disease after challenge, and some birds had diphtheritic tracheitis and laryngitis which appeared identical to that commonly seen under field conditions. Seven days after challenge, fowl pox virus was recovered from the tracheas of unvaccinated birds, but not from the vaccinated ones.

Intercurrent Mycoplasma gallisepticum infection appeared to extend slightly the period of respiratory disease but was not essential for development of the diphtheritic lesion.     

Parainfluenza type 3 virus in cattle with upper respiratory disease

Abstract

Extract

Parainfluenza type 3(Pl₃) virus has been associated with upper respiratory disease of cattle in many countries (Hoerlein et al., 1959 Bögel, K. 1961. Virologische Undersuchungsbefunde bei Kalbern mit respiratoris-chem Syndrom unter besonderer Berucksichtigung der Parainfluenza 3 Myxovirus. Mh. Tierheilk, 13: 129–129. 162. [Cited by Jolly, R. D., (1967), N.Z. vet. J., 15: 43–4.] [Google Scholar]; Bögel, 1961 Campbell, R. S. F. 1972. “Virus diseases of cattle. Virology and Virus Disease”. In Proc. No. 16 of Course for Veterinarians, 132–132. University of Sydney.  [Google Scholar]; Reisinger, 1962 Carter, Margery E. and Hunter, R. 1970. Isolation of parainfluenza type 3 virus from sheep in New Zealand. N.Z. vet. J., 18: 226–227. [Taylor &; Francis Online] , [Google Scholar]; Jolly and Ditchfield, 1965 Curtis, R. A. and Sutton, R. H. 1972. Chronic granular rhinitis (nasal catarrh) of cattle. N.Z. vet. J., 20: 125–125. [Taylor &; Francis Online] , [Google Scholar]). However, PI₃ virus has not been isolated from cattle with respiratory disease in New Zealand although a serological study found that 89.3% of cows had significant levels of antibody against PI₃ virus (Pastier and Hansen, 1966). In most cases infections are subclinical, and there is little evidence to suggest that PI₃ virus is an important cause of disease in New Zealand cattle (Jolly, 1967 Fastier, L. B. and Hansen, N. F. 1966. The occurrence of antibodies to bovine virus diarrhoea, infectious bovine rhinotracheitis and parainfluenza 3 viruses in sera from New Zealand cattle. N.Z. vet J., 14: 27–32. [Taylor &; Francis Online] , [Google Scholar]). This communication records an outbreak of upper respiratory disease in cattle from which PI₃ virus was isolated.     

Cellular and cytokine responses in feathers of chickens vaccinated against Marek's disease

In Marek's disease virus infection, feather follicle epithelium (FFE) constitutes the site of formation of infectious virus particles and virus shedding. The objective of this study was to characterize cellular and cytokine responses as indicators of cell-mediated immune response in FFE and associated feather pulp following immunization against Marek's disease. Analysis of feather tips collected between 4 and 28 days post-immunization (d.p.i.) from chickens vaccinated post-hatch with either CVI988/Rispens or herpesvirus of turkeys revealed that replication of these vaccine viruses started at 7d.p.i., peaked by 21d.p.i., and subsequently, showed a declining trend. This pattern of viral replication, which led to viral genome accumulation in feather tips, was associated with infiltration of T cell subsets particularly CD8+ T cells into the feather pulp area and the expression of cytokine genes such as interferon-gamma, which is an indication of elicitation of cell-mediated immune responses at the site of virus shedding.     

A case of "watery mouth" in a New Zealand Romney lamb

Watery mouth was diagnosed as the cause of illness and subsequent death in a 3-day-old Romney lamb which had not received early colostrum. The history, clinical signs and post-mortem findings were typical of the disease as seen in other countries, including Great Britain. The diagnosis was based on the clinical signs and was supported by an absence of post-mortem findings of other specific neonatal diseases. The potential importance of watery mouth under conditions of intensive husbandry in New Zealand is discussed.     

Transmission from Seed to Seedling and Secondary Spread of Xanthomonas campestris pv. Campestris in Brassica Transplants: Effects of Dose and Watering Regime

The effects of inoculum load and watering regime on the transmission of Xanthomonas campestris pv. campestris from seed to seedlings of cauliflower were investigated. Seed, inoculated with different concentrations of bacteria, was sown in commercial module trays and subjected to four different watering regimes: high frequency overhead spray, low frequency overhead spray, high frequency capillary and low frequency capillary. Visible symptoms were recorded and leaf washings were carried out to detect the pathogen on symptomless plants. The effects of treatments on symptoms and on the proportion of contaminated but symptomless plants was similar. Initially, they were influenced only by the dose of bacteria with little difference between the watering regimes, but later the proportion of plants with symptoms was greater for plants subjected to overhead watering, due to spread and secondary infection. Generalised linear models were fitted to the data relating the proportion of symptomless contaminated plants or the proportion of plants with symptoms, p, to the mean dose of bacteria per seed, d, and the number of overhead waterings, noh. The equations were: p=1–exp(–0.014·d ^0.32·noh ^0.045) for symptomless contaminated/infected plants and p=1–exp(–0.0056·d ^0.44·noh ^0.014) for plants with symptoms. These models indicated that the one-hit probability for transmission of the pathogen (i.e. with/without visible symptoms) was 0.014 and for infection (i.e. with visible symptoms) was 0.0056.