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Biomedical subjects

R F Horner

Publications and source records attributed to R F Horner.

10 recordsLinked to original sources
PubMed2004

Characterization of a pigeon paramyxovirus (PPMV-1) isolated from chickens in South Africa.

A paramyxovirus with a thermostability of 60 min (typical of velogenic viruses) and a mean death time of > 90 h (typical of lentogenic viruses) was isolated from layers near Mooi River, South Africa. Our results, based on comparative nucleotide sequence data indicated that the virus is pigeon paramyxovirus 1 (PPMV-1), a variant of Newcastle disease virus. The F0 cleavage site contains a 112RRKKRF117 motif, and the virus had 98% sequence identity with PPMV-1 strains from the Far East. PPMV-1 was last reported in South Africa during the 1980s, with this being the first report of PPMV-1 isolated from chickens in South Africa.

Animals↗
PubMed2003

A phylogenetic study of South African Newcastle disease virus strains isolated between 1990 and 2002 suggests epidemiological origins in the Far East.

Genetic comparisons were made of the fusion protein sequences of 155 Newcastle disease virus isolates collected in South Africa between 1990 and 2002. Their evolutionary relationships and origins are described. All of the lentogenic field isolates were shown to be derived from commercial vaccines. No true South African lentogenic wild type strain was identified. Furthermore, it was shown that almost all mesogenic isolates had avirulent F(0) cleavage site sequences. Three major epizootics occurred in South Africa during the period of this study. The first outbreak (1990/1991) was caused by viruses endemic to South Africa since the 1960's (genotype VIII) but were occasionally also isolated in 2000. Genotype VIIb viruses, implicated in the severe outbreaks during 1993/1994, persisted until 1999. Genotype VIId viruses, responsible for the most recent outbreak in 1999/2000, had their origins in the Far East like those of the two previous outbreaks.

Amino Acid Sequence↗
PubMed1999

Confirmation that PCR can be used to identify NAD-dependent and NAD-independent Haemophilus paragallinarum isolates.

Seventy five bacteria tentatively identified as Haemophilus paragallinarum (the causative agent of infectious coryza), eight identified as Ornithobacterium rhinotracheale and 13 identified as NAD-independent Pasteurella species were isolated from chickens with respiratory infection in various provinces in South Africa. The isolates were characterized by conventional biochemical and serological methods. A polymerase chain reaction (PCR) assay specific for H. paragallinarum was used to identify the cultures directly from colonies. The PCR assay gave positive results for all isolates that were identified by conventional methods as H. paragallinarum, irrespective of whether they were nicotinamide adenine dinucleotide (NAD)-dependent (43 isolates) or NAD-independent (32 isolates). The eight isolates that were identified by conventional methods as O. rhinotracheale and the 13 isolates identified as various Pasteurella species gave negative results in the PCR assay. This study has demonstrated that colony PCR is a rapid method for uniquely identifying both NAD-dependent and NAD-independent strains of H. paragallinarum and distinguishing them from other bacteria, such as O. rhinotracheale and Pasteurella species.

Animals↗
PubMed1992

Isolation and identification of psittacid herpesvirus 1 from imported psittacines in South Africa.

Acute deaths occurred in 47 out of a total of 131 imported psittacine birds whilst in quarantine. Few and non-specific clinical signs were seen during the course of the disease outbreak, but gross pathology revealed severe hepatomegaly and splenomegaly. A herpes virus was isolated from liver and spleen material taken from 2 birds, an Amazon (Amazona aestiva aestiva) and a Yellow-collared macaw (Ara auricollis). Identification procedures included virus neutralisation tests carried out in chicken embryo fibroblast cultures. Neutralisation of the virus was obtained by antisera to Psittacid herpesvirus type 1 (HV1) but not against HV2 or HV3.

Animals↗
PubMed1988

Poxvirus in farmed Nile crocodiles.

In an outbreak of wart-like skin lesions in nine-month-old farmed Nile crocodiles (Crocodylus niloticus) the lesions were especially common on the head and neck but occurred on all parts of the body except the tail. Eosinophilic intracytoplasmic inclusion bodies were present in epithelial cells and further examination of the lesions by transmission electron microscopy revealed the presence of a poxvirus. An autogenous vaccine was produced from material from the lesions and in six vaccinated crocodiles the lesions healed more quickly than in unvaccinated controls.

Alligators and Crocodiles↗
PubMed1986

Dermatophilus congolensis infection in cattle.

The history, appearance and clinical course of a low incidence, chronic skin disease in beef cattle is reported. Calves were affected from 3 months of age and the condition persisted into adulthood. The infection was caused by Dermatophilus congolensis and resulted in severe crusting of the skin. Sheep were kept on the farm until 4 years ago. The method of diagnosis is discussed.

Actinomycetales Infections↗
PubMed1982

Suspected ammonium nitrate fertiliser poisoning in cattle.

The occurrence of a suspected mixed ammonia and nitrate fertiliser poisoning that led to acute illness and fatalities in cattle is described. The circumstances leading to the incident included the method of application of the fertiliser, low rainfall and the absence of subsequent irrigation of the fertilised pastures. The clinical and gross post mortem findings, principally dehydration and fluid distension of the rumen, were not pathognomonic. The complex of nitrate, nitrite and ammonia toxicity is discussed.

Animals↗
PubMedDate not supplied

Phenotypic and molecular characterization of V-factor (NAD)-independent haemophilus paragallinarum.

In South Africa from early 1989 onward, strains of Haemophilus paragallinarum not requiring nicotinamide adenine dinucleotide (NAD) have been isolated from commercial chickens suffering from infectious coryza. Fifteen of these field isolates were characterized by biochemical typing, serotyping, restriction endonuclease analysis (REA), and ribotyping. The chosen isolates represented diversity in geographic location, time of disease outbreak, and type of flock. All were typical of the species in biochemical properties, except that they were NAD-independent, and all were Page serovar A. REA was performed with three enzymes: HindIII, HpaII, and SspI. All isolates gave identical REA profiles with all three enzymes. Ribotyping was performed using a probe that consisted of the plasmid pUC19 into which the 16S rRNA operon of H. paragallinarum had been inserted. All 15 isolates gave the same ribotyping profile using each of the three enzymes. As a group, the NAD-independent strains gave REA profiles and ribotypes that were very different from a range of classic South African strains isolated before 1989. Our results strongly suggest that the NAD-independent isolates are clonal in nature.

Animals↗