Antiviral Effect of Resveratrol in Piglets Infected with Virulent Pseudorabies Virus.

Pseudorabies virus (PRV) is one of the most important pathogens of swine, resulting in devastating disease and economic losses worldwide. Nevertheless, there are currently no antiviral drugs available for PRV infection. Resveratrol (Res) was identified to exert its antiviral activity by inhibiting the PRV replication in preliminary investigations. In our previous study, we found that Res has anti-PRV activity in vitro. Here, we show that Res can effectively reduce the mortality and increase the growth performance of PRV-infected piglets. After Res treatment, the viral loads significantly (p < 0.001) decreased. Pathological symptoms, particularly inflammation in the brain caused by PRV infection, were significantly (p < 0.001) relieved by the effects of Res. In Res-treated groups, higher levels of cytokines in serum, including interferon gama, interleukin 12, tumor necrosis factor-alpha and interferon alpha were observed at 7 days post infection. These results indicated that Res possesses potent inhibitory activity against PRV-infection through inhibiting viral reproduction, alleviating PRV-induced inflammation and enhancing animal immunity, suggesting that Res is expected to be a new alternative control measure for PRV infection.

Immune response in pigs treated with therapeutic doses of enrofloxacin at the time of vaccination against Aujeszky's disease.

The effect of treatment with enrofloxacin was studied on the postvaccinal immune response in pigs. Forty pigs were used (control not vaccinated (C), control vaccinated (CV), vaccinated, received enrofloxacin (ENRO)). From day -1 to day 3 pigs from ENRO group received enrofloxacin at the recommended dose. Pigs from ENRO and CV groups were vaccinated twice against Aujeszky's disease virus (ADV). There was a significant delay in the production of humoral response of enrofloxacin dosed pigs when compared with CV group. Moreover, in ENRO group the significant decrease in IFN-γ production and significantly lower values of stimulation index after ADV restimulation was noted, as compared with CV group. The secretion of IL-6, IL-10 and TNF-α by PBMC after recall stimulation was also affected in ENRO group. The results indicate that enrofloxacin, in addition to its antimicrobial properties, possess significant immunomodulatory effects and may alter the immune response to vaccines.

[Observation on the central afferent pathway of "Guanyuan" (CV 4) under normal and pathological states and the influence of electroacupuncture].

OBJECTIVE: To investigate the afferent pathways of "Guanyuan" (CV 4) under normal and pathological states and to observe the effect of electroacupuncture (EA) on them. METHODS: Twenty-four female SD rats were randomly divided into normal control (NC), NC + EA, ovariectomy (OVX) and OVX + EA groups, with 6 cases in each. Four weeks after OVX, Pseudorabies Virus (PRV, 10 microl liquid containing 10(8) plaque-forming units) was injected into CV4. Thirty minutes after PRV injection, EA (2 Hz, 2-3 mA) was applied to CV4 for 30 minutes, once daily for 3 days. Six hours after the third EA treatment, all the rats were perfused transcardially with 4% paraformaldehyde under anesthesia, followed by sampling the brain and spinal cord and cutting into sections (35 microm). Immunohistochemical method (rabbit anti-rat beta-galactosidase) was used to display PRV immunoreactive (PRV-IR) positive neurons. RESULTS: 1) After injection of PRV, PRV-IR positive cells widely distributed in the spinal cord (cervical, thoracic and lumbar segments), brain stem (nucleus of solitary tract, cuneate nucleus, gigantocellular reticular nucleus, nucleus of spinal tract of trigeminal nerve, nucleus raphe magnus, locus caeruleus, etc), hypothalamus and cerebral cortex in each group. 2) After OVX, apparently fewer PRV-IR positive cells were found in some nuclei as medial septum nucleus (MSN), arcuate nucleus (ARC), diagonal band nucleus (DBN), paraventricular nucleus (PVN) which have close relation with endocrine activity (P<0.05); and rarely seen in ventromedial hypothalamus (VMH) and lateral preoptic area (LPO) (P<0.01). But in OVX + EA group, PRV-IR positive cells in above regions or nuclei increased significantly (P<0.05 or P<0.01). No obvious difference was found between NC and NC+ EA groups in the number of PRV-IR positive cells (P>0.05). CONCLUSION: Following OVX, PRV-IR positive cells in neuroendocrine-related nuclei of hypothalamus reduced significantly in number; EA of "Guanyuan" (CV 4) can promote the recovery of these neurons in above mentioned nuclei.

[Changed health problems in a changing pig-farming concern in The Netherlands until 1980]. / Veranderende gezondheidsproblematiek in een veranderende varkenshouderij in Nederland tot 1980.

In 1905 Poels published 'Disease of swine in the Netherlands'. This book dealt predominantly with swine fever, erysipelas, tuberculosis and 'pneumonia'. Between 1920 and 1940 others reported on streptococci, lobular haemmorrhagic pneumonia, bordetellosis, Aujeszky's disease and postweaning diarrhoea. After the second world war, particularly after 1960, the Dutch pig-farming industry developed at a tremendous rate. As a consequence, the health problems changed. Certain diseases became less important: tuberculosis, erysipelas, Leptospira tarrasovi, enteroviruses. Yet other diseases including postweaning diarrhoea, atrophic rhinitis and Aujeszky's disease became problems of increasing importance. At the end of the seventies the knowledge of E. coli toxin types was substantial. On the other hand, information concerning the pathogenesis and pathophysiology was very limited. Bordetella bronchiseptica was still considered to be the most important agent in AR, zootechnical factors being predisposing. However, one was aware of missing links. Aujeszky's disease was obscure until the late fifties. Until 1972 only occasional reports were made. In that year, an epidemic occurred in the Gelderse Vallei. Another epidemic occurred in 1974 in the provinces of Brabant and Limburg. By 1980 proper vaccines were available and Aujeszky's disease was not yet a political problem.

Population biology of pseudorabies in swine.

A deterministic mathematical model of the population biology of pseudorabies in swine was used to clarify some of the basic features of the host-virus relationship and to inquire into the circumstances that promote or impede virus persistence in a single herd. When the basic reproductive rate of the infection (ie, the number of secondary infections resulting from the introduction of a single infective animal into a wholly susceptible herd) is greater than unity, the model suggests that the number of infective individuals in the herd will undergo highly damped oscillations to a final equilibrium level. The most important determinants of virus persistence are herd size and the density at which sows are maintained. There is a threshold density of susceptible individuals below which the virus will eventually be eliminated from the herd, even when specific control measures are lacking. Test and removal strategies hasten virus elimination when herd density is already below threshold, but are otherwise likely to succeed only when the removal of latent infections reduces the basic reproductive rate of the infection below unity. Vaccination strategies may also result in virus elimination, but only in relatively small herds.

Tests on protection against viral diseases.

Despite many attempts to find reliable in vitro criteria for the efficacy of Biological Response Modifiers--BRMs (immunomodulators, paramunity inducers) animal challenge models are still the only way to demonstrate the totality of interlocking defense mechanisms. Challenge models with mouse pathogenic viruses provide an excellent possibility to study protective effects of BRMs against acute or chronic forms of viral diseases. For comparative studies two completely different virus challenge models--Pseudorabies PR and Stomatitis Vesicularis VSV--were developed with adult and baby NMRI mice respectively. The potency of BRMs in preventing lethal disease reveals significant differences depending upon the sort of BRM, the route of application and the time of pretreatment. Defense mechanisms important for the control of Pseudorabies virus infection in adult NMRI mice were tested in vitro (ex vivo) and correlated well with the degree of protection in vivo. Comparison of BRM efficacy in selective viral challenge models combined with screening of a variety of antiviral defense functions in infected animals in vitro provide reliable methods in demonstrating the potency of BRMs against viral infections.