Vilmos Pálfi

Use of valnemulin in the control of Mycoplasma bovis infection under field conditions

In a blind trial, alternate calves in six consecutive production batches of calves (total 70), on a farm with a high incidence of respiratory and reproductive disease, were allocated to treatment with either valnemulin or a placebo premix added to the milk from four days of age. The calves were weighed at the beginning and end of a 21-day period of medication. Blood samples and nasal swabs were taken and examined for the presence of Mycoplasma and Pasteurella species, and antibodies to viral agents. Clinical condition, rectal temperature, respiratory and other signs and refusals of milk were recorded daily. Dead calves were examined postmortem. The calves medicated with valnemulin gained weight more quickly, had fewer cases of Mycoplasma infection and fewer respiratory signs, and required fewer treatments with antibiotics than those in the placebo group.

Clinical study of the disease of calves associated with Mycoplasma bovis infection.

Clinical, bacteriological and serological examination of 35 calves from the age of 5 to 26 days was performed in a Holstein-Friesian dairy herd endemically infected with Mycoplasma bovis. M. bovis was isolated from 48.6% of nasal swabs taken from the calves at the age of 5 days, and from 91.4% of the same calves at the age of 26 days, indicating the gradual spread of infection. The isolation rate of Pasteurella multocida did not change much, and varied from 28.6 to 25.7%. No P. haemolytica could be detected. In addition to M. bovis and P. multocida, the herd was also infected with different viruses (including bovine viral diarrhoea virus, infectious bovine rhinotracheitis virus, bovine adenoviruses, parainfluenza-3 virus, and bovine respiratory syncytial virus) as a large proportion of the sera of newborn calves contained colostral antibodies against these viruses. In most of the newborn calves severe clinical signs (fever, depression, inappetence, hyperventilation, dyspnoea, nasal discharge and coughing) due to M. bovis infection developed. The clinical signs appeared already on the fifth day of life, and their incidence was the highest at the age of 10 to 15 days. Three calves (8.6%) died as a result of severe serofibrinous pneumonia. The surviving calves showed very poor weight gain (ranging from 1.5 to 3.5 kg) during the first two weeks of life.

The role of egg drop syndrome virus in acute respiratory disease of goslings.

An outbreak of severe acute respiratory disease characterized by tracheitis and bronchitis was observed in young goslings on a large-scale goose farm in Hungary. Histological examination revealed amphophilic intranuclear inclusion bodies in the superficial epithelial cells of the trachea and bronchi. Adenovirus-like particles were detected by electron microscopy, and the virus isolated from the trachea and the lungs was identified as egg drop syndrome (EDS) virus by serological and genomic examination. The clinical and pathological signs were reproduced by intratracheal administration of the virus isolate to 1-day-old goslings free of EDS antibodies. The presence of EDS virus DNA in different organs of the naturally and experimentally infected goslings was detected by polymerase chain reaction. This is the first report on the involvement of EDS virus in severe respiratory disease of geese.

First description of swine torque teno virus (ttv) and detection of a new genogroup in hungary: Short communication

Torque teno virus (TTV) belongs to the floating genus of Anellovirus. It was discovered in a human patient, and later it was also found in animals including pigs. The aim of this study was to investigate the presence and estimate the prevalence of swine TTV in Hungarian pig herds for the first time, and to characterise the viruses found. Serum samples of 82 adult swine from 13 piggeries and 44 weaned pigs from one large herd were tested by PCR for the presence of TTV DNA. Viral DNA was found in 30% of the adult swine and 73% of the weaned pigs tested. Liver and intestine of weaned pigs were also tested and found to be infected at a lower rate. The TTV sequences found in sera and intestines were similar and could be clustered as swine genogroup 1. However, the sequences derived from one liver were remarkably different from all other known genogroups and seemed to represent a new genogroup.

Immunogenicity of Poxvirus Vector Avian Influenza Vaccines in Muscovy and Pekin Ducks

Abstract Fowlpox (FP)-vectored avian influenza (FP-AI) vaccines are used in 1-day-old chickens, but they have also recently been shown to be immunogenic in ducks. The objectives of this work were 1) to evaluate safety and to compare the immunogenicity in ducks of three poxvirus vectors (fowlpox, canarypox, and vaccinia) expressing the same hemagglutinin gene from an H5N1 isolate, 2) to study the effect of the dose of the FP-AI and the presence of an adjuvant in 1-day-old Pekin ducks on antibody response after a boost with inactivated vaccine given 3 wk later, and 3) to confirm the immunogenicity of such a heterologous prime-boost vaccination scheme in 1-day-old Muscovy ducks. Immunogenicity induced by the three poxvirus vectors was comparable, and the FP vector was selected for the other studies. As published previously, there was a strong dose effect of the FP-AI priming on the hemagglutination inhibition (HI) titers induced after the boost with an inactivated vaccine. In contrast, the two tested adjuvants did not significantly increase the activity of FP-AI priming. The heterologous prime-boost regimen given to both Muscovy and Pekin ducklings at 1 and 14 or 21 days of age, respectively, was shown to be at least as immunogenic as two administrations of inactivated vaccines given at 2 and 5 wk of age. However, HI antibody titers were of short duration for both vaccine schemes, and their persistence was heterogeneous among individual birds.

A survey of equine abortion and perinatal foal losses in Hungary during a three-year period (1998-2000)

Cases of equine abortion and perinatal foal losses were investigated in Hungary during a three-year period (1998-2000). Samples from aborted equine fetuses and newborn foals (total n = 96) were examined using bacteriological, virological, pathological, immunohistochemical (IHC), molecular biological and serological methods. The cause of abortion and perinatal foal loss was identified in 67/96 cases (70%); viral infection was found in 22 (23%), viral and bacterial coinfection in 1 (1%), bacterial infection in 23 (24%), protozoan infection in 1 (1%) and fungal infection in 2 cases (2%). Morphological lesions suggestive of infection were recorded in 2 (2%) and non-infectious causes in 16 cases (17%).

Molecular characterisation of the ORF68 region of equine herpesvirus-1 strains isolated from aborted fetuses in Hungary between 1977 and 2008

Equine herpesvirus-1 (EHV-1) can be classified into distinct groups by single nucleotide polymorphisms (SNPs) in their genomes. Only a few of these can be associated with a special attribute of the virus. Differences in the ORF30 region can determine the neuropathogenic potential, while by substitutions in the ORF68 region several strain groups can be made. In previous studies no connection was found between the neuropathogenic potential and the SNPs in ORF68, but the occurrence of members of distinct groups in different outbreaks can facilitate epidemiological investigations because the geographical distribution of a particular group is very often specific. The present study aimed at the molecular examination and grouping of 35 EHV-1 strains isolated from aborted equine fetuses in Hungary between 1977 and 2008. Genotyping was based on the comparison of nucleotide sequences of a polymorphic segment located in the ORF68 region, which had previously been found to be a useful tool for classification. After sequencing this region, the Hungarian EHV-1 isolates could be classified into seven groups. Only 23 of the 35 isolates belonged to the formerly described groups, while the SNPs of 12 isolates diverged, and four new groups could be set up. In addition, phylogenetic analysis was performed to compare the ORF68 sequences of the Hungarian strains with the sequences of isolates from Europe, America and Australia. The number of newly formed groups suggests that the further analysis of unknown EHV-1 isolates would involve the emergence of extended numbers of new groups, which can impair the usability of this grouping method.

MICROBIOLOGICAL AND PATHOLOGICAL EXAMINATION OF FATAL CALF PNEUMONIA CASES INDUCED BY BACTERIAL AND VIRAL RESPIRATORY PATHOGENS

The infectious origin of fatal cases of calf pneumonia was studied in 48 calves from 27 different herds on postmortem examination. Lung tissue samples were examined by pathological, histological, bacterial culture, virus isolation and immunohistochemical methods for the detection of viral and bacterial infections. Pneumonia was diagnosed in 47/48 cases and infectious agents were found in 40/47 (85%) of those cases. The presence of multiple respiratory pathogens in 23/40 (57.5%) cases indicated the complex origin of fatal calf pneumonia. The most important respiratory pathogens were Mannheimia-Pasteurella in 36/40 (90%) cases, followed by Arcanobacterium pyogenes in 16/40 (40%) cases, Mycoplasma bovis in 12/40 (30%) cases, and bovine respiratory syncytial virus in 4/40 (10%) cases. Histophilus somni was detected in 2/40 (5%) cases, while bovine herpesvirus-1, bovine viral diarrhoea virus and parainfluenza virus-3 were each found in 1/40 (2.5%) case. Mastadenovirus, bovine coronavirus, influenza A virus or Chlamydiaceae were not detected.