Commercialization of veterinary viral vaccines.

If vaccines are to reliably prevent disease, they must be developed, produced and quality-controlled according to very strict regulations and procedures. Veterinary viral vaccine registrations are governed by different rules in different countries, but these rules all emphasize that the quality of the raw materials--the cells, eggs, animals or plants that are used in production--need to be carefully controlled. The veterinary vaccine business is also very cost-conscious. Emphasis over the last 5-10 years has therefore been to develop culture systems that minimize labor and sterility problems and thus provide for reliable and cost-effective production. Implementing these often more complex systems in a production environment takes considerable effort, first in scale-up trials and further down the line in convincing production personnel to change their familiar system for something new and possibly untried. To complete scale-up trials successfully, it is absolutely necessary to understand the biochemistry of the cells and the influence of the virus on the cells under scale-up and later production conditions. Once a viral product can be produced on a large scale, it is imperative that the quality of the end-product is controlled in an intelligent way. One needs to know whether the end-product performs in the animal as was intended during its conception in the research and development department. The development of the appropriate tests to demonstrate this plays an important role in the successful development of a vaccine.

Efficacy of an inactivated aqueous-suspension Newcastle disease virus vaccine against paramyxovirus type 1 infection in young pigeons with varying amounts of maternal antibody.

Pigeons aged 3 weeks were vaccinated, subcutaneously, with an inactivated aqueous-suspension LaSota vaccine. Irrespective of the level of maternally-derived antibodies the single vaccination gave protection lasting 1 year as shown by resistance against an intramuscular challenge with a virulent 'pigeon' PMV-1 strain.

Rate of increase of Autographa californica nuclear polyhedrosis virus in Trichoplusia ni larvae determined by DNA:DNA hybridization.

The rate of increase and doubling time of the HOB clone of Autographa californica nuclear polyhedrosis virus (AcMNPV-HOB) in neonate Trichoplusia ni larvae was determined by measuring the increase in viral DNA through time following inoculation with average doses of 50 or 17,400 occlusion bodies per larva. Changes in total DNA and viral DNA through time were followed by fluorescence spectroscopy and quantitative slot-blot DNA:DNA hybridization, respectively. Total DNA content (i.e., larval DNA and viral DNA) of larvae infected with the intermediate dose lagged behind that of noninfected larvae 30 hr post-inoculation (p.i), reached a maximum at 51 hr p.i., and stayed constant thereafter. The total DNA content of larvae inoculated with the high dose lagged behind that of the control group from 18 hr p.i. and increased slowly until death of the larvae (ca. 48 hr p.i.). The amount of viral DNA in larvae inoculated with the intermediate dose increased exponentially between 15 and 42 hr p.i., reached a maximum at 48 hr p.i., and stayed constant until 68 hr p.i., by which time most larvae had died. The amount of viral DNA in larvae inoculated with the high dose did not increase exponentially; initially the rate of increase was the same as that for larvae inoculated with the intermediate dose but became progressively lower after 13 hr p.i. Calculations of the rate of increase for AcMNPV-HOB in neonate T. ni larvae inoculated with the intermediate dose and incubated at 29 degrees C resulted in a value of 0.264 hr-1 (doubling time: 2.63 hr).(ABSTRACT TRUNCATED AT 250 WORDS)