Pathogenesis and Subsequent Cross‐Protection of Influenza Virus Infection in Pigs Sustained by an H1N2 Strain

The H1N1, H3N2 and, more recently, H1N2 subtypes of influenza A virus are presently co‐circulating in swine herds in several countries. The objectives of this study were to investigate the pathogenesis of Sw/Italy/1521/98 (H1N2) influenza virus, isolated from respiratory tissues of pigs from herds in Northern Italy, and to evaluate its potential cross‐protection against the Sw/Fin/2899/82 (H1N1) strain. In the pathogenesis test, eight pigs were intranasally infected with H1N2 virus; at pre‐determined intervals, these animals were killed and necropsied, along with eight uninfected animals. In the cross‐protection test, sixteen pigs were infected by intranasal (i.n.) and intratracheal (i.t.) routes with either H1N2 or H1N1 virus. Twenty days later, all pigs were challenged (by the same route), with either the homologous H1N2 or heterologous H1N1 virus strains. Control group was inoculated with culture medium alone. On post‐challenge days (PCD) 1 and 3, two pigs from each infected group, along with one control pig, were killed. Clinical, virological, serological and histopathological investigations were performed in both the pathogenicity and cross‐protection tests. In the pathogenicity test, mild clinical signs were observed in two pigs during 3 and 4 days, respectively. Virus was isolated from two pigs over 6 days and from lung samples of pigs killed on post‐infection days 2 and 4. Seroconversion was detected in the two infected animals killed 15 days after infection. In the cross‐protection study, mild clinical respiratory signs were detected in all pigs infected with either the H1N2 or H1N1 virus. The virus was isolated from nasal swabs of almost all pigs till 6 days. After the challenge infection, the pigs remained clinically healthy and virus isolation from the nasal secretions or lung samples was sporadic. Antibody titres in H1N1 or H1N2 infected groups were similar, whereas the H1N2 sub‐type induced less protection against re‐infection by homologous and heterologous virus than H1N1 sub‐type. The controls had no signs of the disease. In the H1N2 infected pigs, a reduced number of goblet cells in nasal and tracheal mucosa and small foci of lymphomononuclear cell infiltrates in the submucosa were detected. Furthermore, the goblet cell reduction was related to the time of infection. Diffuse mild interstitial pneumonia was also recorded in pigs infected with the H1N2 virus and challenged with either H1N1or H1N2 pigs. These studies showed the moderate virulence of the H1N2 virus and a partial cross‐protection against heterologous infection.     

A comparison of the humoral and cell-mediated response of pigs experimentally infected with either influenza or PRRS viruses

Veterinary Research Communications -     

Immunization against bovine herpesvirus-1 infection. Preliminary tests in calves with a DNA vaccine

A bovine herpesvirus-1 (BHV-1) vaccine expressing glycoprotein D, the form with the transmembrane anchor removed, was evaluated for inducing immunity in calves. The plasmid encoding gD of BHV-1 was injected three times to nine calves, using three animals for each of the following routes: intramuscularly (i.m.), intradermally (i.d.), or intranasally (i.n.). Three additional calves were given the plasmid vector only and served as unvaccinated controls. When calves were subjected to challenge infection with BHV-1, all vaccinated calves as well as the controls developed a typical severe form of infectious bovine rhinotracheitis. However, compared to the controls, the vaccinated calves showed earlier clearance of challenge virus. Moreover, the calves given the vaccine i.m. developed neutralizing antibody to BHV-1 between 21 and 42 days following the first injection of vaccine, whereas in calves vaccinated either i.d. or i.n., as well as the controls, antibody first appeared in their sera 14 days post-challenge infection.     

Use of innovative methods in the eradication of bovine tuberculosis

During final phases of eradication programmes, strains of Mycobacterium sp. not belonging to the tuberculosis complex increase their relative frequency and are responsible for positive skin test reactions. Moreover, the specificity of any indirect diagnostic test, such as the skin test, is never completely accurate, therefore even when tuberculosis infection is completely eradicated, a number of false positive reactions are to be expected. The aim of this paper is to evaluate the performances of traditional isolation/typing techniques, automatic isolation/typing techniques based on fluorimetric detection of bacterial growth (Bactec), skin tests and the -interferon test. Samples examined for the evaluation of test sensitivities originated from 154 infected animals belonging to 32 infected herds. Samples used as negative controls in the evaluation of test specificities originated from 86 animals of nine officially infection-free herds. The automatic isolation/typing technique based on fluorimetric detection of bacterial growth showed higher sensitivity than the traditional isolation typing technique. Moreover, it allowed a safer processing of bacterial cultures, decreasing the risk for laboratory workers. The observed performance of the gamma-interferon test was considered beneficial in that it increased the sensitivity of individual diagnosis within an infected herd, especially in 'problem herds', but its poor specificity did not improve detection of infected herds compared to the skin test.     

Der Lanforser Bestand

Ohne ZusammenfassungJm Heft 26, Nr. 3, 1931, Mitt. aus der forstlichen Bersuchsanstalt Schwedens, habe ich neulich eine Abhandlung veröffentlicht, in der ein votlftändiger Bericht über diesen Bersuch mitgeteilt und Näheres zu ersehen ist.     

Congenital diffuse hyperplastic goiter associated with perinatal mortality in 11 captive-born bottlenose dolphins (Tursiops truncatus).

Diffuse hyperplastic goiter was diagnosed by histopathology in 11 perinatal bottlenose dolphins (Tursiops truncatus) that died at four separate zoos and aquaria. Thyroid morphology of these animals was compared with the histologically normal thyroids of two stranded wild bottlenose dolphin calves, a neonate and a 2-mo-old calf. Histologic changes included reduced follicular luminal diameter, markedly reduced or absent luminal colloid, hypertrophy of follicular epithelium, and follicular dysplasia. The etiology of the thyroid gland lesion was not identified. Cause of death was not determined for most of these animals, but they were presumed to have died from metabolic derangements associated with the thyroid lesion, drowning, or dystocia.     

Prevalence and Genotypic Characterization of Clostridium difficile From Ruminants in Switzerland

Clostridium difficile is an emerging enteric pathogen of humans and animals with a known main reservoir in the intestinal tract of various warm‐blooded animals. This study was carried out to evaluate the prevalence of C. difficile in 150 rectal swab samples collected from cattle and goats in Switzerland. The overall prevalence of C. difficile was 6.6%. The isolates belonged to the PCR ribotypes 033, 066, 070, 003, 001 and 137. In addition, the occurrence of C. difficile in faecal samples collected from farm ground was also evaluated and C. difficile was detected in 21% (7/30) of these samples. These isolates belonged to ribotypes 033, 066, 014 and 137. Several isolates pertained to ribotypes known to cause Clostridium difficile infections in humans.     

Evaluation of safety and efficacy of DNA vaccines against bovine herpesvirus-1 (BoHV-1) in calves

Four DNA vaccines against BoHV-1 were evaluated for their efficacy in calves. Twelve animals were divided into four groups which were injected with four different DNA vaccines: pVAX-tgD (Vaccine A); pVAX-tgD co-immunised with pVAX-48CpG (Vaccine B); pVAX-UbiLacI-tgD-L (Vaccine C); pVAX-UbiLacI-tgD-L co-immunised with pVAX-48CpG (Vaccine D). Three additional calves were given the plasmid vector and served as controls. Ninety days after the first vaccination all calves were challenge infected with BoHV-1.All animals developed a severe form of infections bovine rhinotracheitis. Only the calves given the pVAX-tgD co-immunised with pVAX-48CpG (Vaccine B) developed humoral antibodies against BoHV-1 between 56 and 90 days after the first vaccination, whereas in calves of other groups and in the controls, antibodies appeared only after the infection. In the calves vaccinated with either pVAX-tgD (Vaccine A) or pVAX-tgD combined with pVAX-48CpG (Vaccine B), BoHV-1-specific IFN-γ secreting cells were detected in PBMCs 90 days after the first vaccination and their number increased after challenge exposure. In the other groups the IFN-γ secreting cells were detected after virus infection and at low values.