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Bovine adenovirus type 7 was isolated from a 10-month-old calf with fibrinopurulent pneumonia and from 2 newborn calves with pneumoenteritis. The viruses were isolated on calf lung and adrenal gland cell cultures and were identified as serotype 7 by immunoelectron microscopy and serum-neutralization tests.

An indirect fluorescent antibody test was developed for routine identification of a porcine adenovirus and its specific antibody. Two specific-pathogen-free young pigs were inoculated with the viral antigen prepared in continuous porcine kidney cell cultures, and their sera were used as an antibody reagent to standardize the test. Sera of adult pigs with respiratory problems, obtained from pig farms in Quebec, were tested for antibodies to this virus; 83 of 540 sera tested (15.2%) were found to be positive.

Proof that inclusion body hepatitis of chickens (IBHC) is caused by a virus (IBHV) was established in 1973. Characterization of IBHV has been conducted by employing the standard criteria for virus classification. The results have indicated that IBHV is a member of the avian adenovirus group. However, no antigenic relationship was found between IBHV and two other avian adenovirus isolates (CELO and Indiana C) as observed by hemagglutination (HA) and virus-serum neutralization tests. Another adenovirus isolate was found to be serologically different from IBHV (Tipton strain) but it incited typical IBHC in susceptible chicks. A novel antigen, detectable by the agar gel immunodiffusion test, was demonstrated in livers from chicks infected experimentally with IBHV. This antigen was able to give a specific precipitin reaction with serums from chickens previously exposed to IBHV. Repeated embryo passage of IBHV lowered its pathogenicity for susceptible chickens. Protection of chickens against IBHV challenge was obtained by vaccination with high embryo passage IBHV (Tipton strain). It was also found that subcutaneous administration of the vaccine virus induced a better immune response than the eye-drop route as observed by the virus-serum neutralization index obtained.

Primary kidney cell cultures were prepared from 68 three-day-old calves. Complete monolayers of these cultures were infected separately with viral diarrhea, infectious bovine rhinotracheitis, parainfluenza, and adenovirus 7 viruses. The yield of virus from all infected cultures was calculated by plaque titer assay after 2 to 4 days' incubation. The variation of virus yield was substantial between individual cultures.

Twenty-four Beagle pups with high levels of maternal antibody to canine adenovirus type 1 (CAV-1) and canine adenovirus type 2 (CAV-2) were oronasally inoculated with CAV-2 at 4 weeks of age. The CAV-2 was isolated from pharyngeal swabs on postinoculation days 2 through 6. In spite of the infection, maternal antibody continued to decrease for 4 to 8 postinoculation weeks, and then homologous CAV-2 neutralizing antibody and, to a lesser extent, CAV-1 neutralizing antibody began to increase. When these pups were challenge inoculated with CAV-1 and CAV-2 at a time when maternal antibody to CAV-1 would normally have disappeared, they were immune. In addition, 3 pups with maternal antibody to CAV-1 and CAV-2 were intramuscularly inoculated with CAV-2 at 3 weeks of age. Virus was not isolated from these pups, and maternal antibody decreased at a normal rate. These pups were not immune to challenge inoculation with CAV-1 and CAV-2.

Four isolates of bovine adenovirus type 4 were recovered from Oregon cattle. One isolate was recovered from a 1-week-old calf with pneumoenteritis, and 1 isolate from an 8-month-old bull with fever and respiratory disease. Two isolates were recovered as latent viruses in testicular cell cultures. All 4 isolates of the virus were shown to have certain physical, chemical, biologic, and antigenic characteristics similar to previously described strains of bovine adenovirus type 4. Of 246 adult beef and dairy cattle in Oregon, 51% had serum-viral neutralizing antibodies to the type 4 virus at the 1:8 dilution level.

Hemagglutinating DNA viruses of 20 nm diameter were isolated from bovine adenovirus types 1 and 2. The isolates were heat stable, chloroform resistant, and defective. Their densities were 1.38 to 1.39 g/cm3, and they were found to be serologically identical to the bovine adeno-associated virus strain X7. A partial antigenic relationship was found between these and the canine adeno-associated virus.

The effect of heavy and light avian adenovirus-associated viral (A-AV) particles on the replication of several adenovirus serotypes was studied in chicken embryo kidney cells. There was a significant decrease (P less than 0.05) in the number and size of adenovirus-induced plaques at A-AV multiplicities of infection greater than 40. Enhancement of plaque production was observed when A-AV multiplicities of infection were 1 to 40. There was a significant increase in the number and size of infective centers. Analysis of cellular yields indicated an increase in the number of adenoviruses produced per cell. Heavy A-AV particles of buoyant density 1.42 g/cm3 in CsCl were found to enhance plaque production more than light particles (1.38 g/cm3). Conversely, light particles showed greater inhibition of plaque production. Adenovirus serotypes varied in their response to enhancement or inhibition by A-AV particles of different density.

This report describes the isolation and identification of a strain of bovine adenovirus type 1 from a cow in a herd that had undergone an episode of diarrhea and abortions. This strain of bovine adenovirus type 1 did not agglutinate either guinea pig or human 0 erythrocytes, and no 20-nm virus particles were evident by electron microscopy, further indicating that it was not contaminated by adenovirus-associated virus.

An adenovirus was isolated from a foal with respiratory tract disease. The virus produced cytopathic effects (CPE) in equine embryo kidney (EEK) cell culture, contained deoxyribonucleic acid (DNA), was resistant to chloroform and pH 3, and was moderately resistant to heat. The virus caused hemagglutination of human (type O) erythrocytes. Viral density was 1.34 g/cm,3 and diameter was 75 nm. An adenovirus-associated virus (AAV) isolated from the infected cell culture was 22 nm in diameter. These viruses are classified as equine adenovirus and equine AAV.

Young lambs, inoculated with ovine adenovirus isolate RTS-151, were killed sequentially (to postinoculation day 21), and their morphologic lesions were studied. Lesions were found only in the respiratory tract and were most severe in the terminal airways. Many cells of the respiratory epithelium had severe cytomegaly and karyomegaly with intranuclear inclusions. Desquamation of affected cells was accompanied by hyperplasia of airway and alveolar epithelium and by accumulation of necrotic cellular debris and neutrophils in terminal airways and alveoli. Virus replicated in the nucleus of enlarged epithelial cells in the airways, but not in alveolar epithelium. Intranuclear inclusions representing viral replication progressed from clumps of finely granular material without virions to a granular material with virions and finally to a dense inclusion with numerous virions.