Experimental infection and cross protection tests in calves with cytopathic strains of bovine rotavirus

Four cytopathic strains (81/32F, 81/36F, 81/40F, 82/80F) of bovine rotavirus were shown to be pathogenic for conventionally reared newborn calves. Calves were infected orally, using 3 calves for each isolate. All became febrile, were depressed and diarrhoeic. Two calves, one of which in the group of those infected with 81/36F isolate, and the other infected with strain 81/40F, were killed when moribund. A 3rd calf from the 81/36F infected group, died. At necropsy localized lesions of the small intestines, which are considered to be typical of rotavirus infection, were found. Virus was consistently isolated from the fecal samples of the inoculated calves up to 13 days post-inoculation. It was speculated that some differences existed in the virulence of the bovine rotaviruses tested. The cross protection tests revealed that 1 strain (81/36F) might be antigenically more complex than the others.     

Reactivation of Bovid herpesvirus 1 and 2 and Parainfluenza-3 virus in calves latently infected

Two experiments were carried out to determine whether Bovid herpsvirus (BHV) 2 is able to induce a recurrent infection in experimentally infected calves. In the first experiment the stress induced by dexamethasone (DMS) treatment failed to reactivate the clinical condition or to induce shedding of BHV2. However, treatment with DMS reactivated a latent BHV1 infection in all calves previously inoculated with BHV2 and also in two noninoculated controls. Probably, because of the interference by BHV1 the study failed to resolve the question as to whether BHV2 could induce a recurrent infection. Consequently, a second experiment was performed using calves devoid of antibody to BHV1 and, therefore, probably, free of virus. By this study it was demonstrated that BHV2 can remain as a latent infection in cattle, which, when immunosuppressed as with DMS, can be reactivated. A finding of considerable interest in this experiment was that in 1 calf a concurrent piroplasma infection was also, unexpectedly, discovered.Recrudescence of latent BHV1 infection was induced by DMS treatment of calves possessing antibody to the virus. The infection once reactivated, was readly transmitted by contact to three other calves devoid of antibody to BHV1. In the same experiment Parainfluenza-3 (PI-3) virus was unexpectedly isolated from all calves. It was speculated that all calves were latently infected with PI-3 virus with concurrent infection by BHV1 acting as a stress inducing PI-3 reactivation.These studies seem to indicate that mixed infections could have an important role in the mechanism involved in the establishment of latent infections and viral reactivation.     

Serological comparison of Bovid herpesvirus 2 and Herpes simplex virus by reciprocal neutralization kinetic studies

Antigenic comparison between two strains of Bovid herpesvirus 2 and Herpes simplex-1 and -2 has been performed using the reciprocal neutralization kinetic method.

The NK values obtained indicate a clear serologic difference between the bovine (69/1LO and Allerton) and the human (HSV-1 and -2) viruses.     

Cervid herpesvirus 2 infection in reindeer: A review

Herpesviruses of the genus Varicellovirus are known to infect and cause disease in a variety of ruminant species, but the impact of cervid herpesvirus 2 (CvHV2) in reindeer (Rangifer tarandus) is mostly unknown. Reindeer is a circum-polar species with a total estimated number of more than 5 million animals. Mortality may reach high values, as in northern Norway, especially in calves (37%; 2005–2006), and disease can potentially account for some of this mortality. CvHV2 has been isolated during a natural outbreak of infectious keratoconjunctivitis, indicating an etiologal link. Serological screening has shown that CvHV2 infection is prevalent in Northern Norway and experimental infection studies have demonstrated that viremia, latency and vertical transmission occur for CvHV2. The present review aims at summarizing current knowledge on the epidemiology, pathogenesis and molecular virology of CvHV2.     

A study in calves of an immunologic relationship between herpes simplex virus and Bovid herpesvirus 2

Calves were inoculated subcutaneously with Herpes simplex virus (HSV), types 1 and 2, previously inactivated with Triton X100. Thirty-nine days later the calves were challenged either by intradermal or intravenous injection of Bovid herpesvirus 2 (BHV2).The clinical reponse of HSV preimmunized calves to BHV2 infection was milder than that in the challenge control calves, and the titer of BHV2 underwent a reduction in the preimmunized calves. BHV2 apparently enhanced the immuno-competent system of the preimmunized calves to produce antibody to HSV.From these results it appeared that HSV partially protected calves against experimentally induced BHV2 infection.     

Distribution of latent bovine herpesvirus 2 DNA in tissues of experimentally infected sheep

The biology of latent infection by bovine herpesvirus 2 (BoHV-2), the agent of mammillitis in cows, remains largely unknown. We herein report attempts to reactivate the latent infection and investigated the sites of BoHV-2 latency in experimentally infected sheep. Ewes inoculated with BoHV-2 in the udder’s skin shed virus for up to five days, developed mammillitis and seroconverted. However, attempts to reactivate latent infection by dexamethasone administration at day 40 pi failed. Nevertheless, viral DNA - and not infectious virus - was detected by PCR in several nerve ganglia and/or regional lymph nodes (LNs) of all animals at day 40 post-reactivation. Likewise, lambs previously inoculated with BoHV-2 in the nose harbored latent viral DNA in trigeminal ganglia, tonsils and regional LNs. These results demonstrate that BoHV-2 establishes latent infection in nerve ganglia and in regional lymphoid tissues, yet virus reactivation is not easily achieved by standard protocols used.     

Latent herpesvirus infection in red deer: characterization of a specific deer herpesvirus including comparison of genomic restriction fragment patterns

Glucocorticoid treatment of imported red deer (Cervus elaphus), seropositive to Infectious Bovine Rhinotracheitis (IBR) virus, reactivated a latent herpesvirus infection, which was transmitted to a seronegative deer with a fatal outcome. However the virus did not spread to cattle housed in close contact with the infected deer, and serological indication og infection in the cattle was observed only on direct nasal installation of virus. The virus isolate had characteristics in common with other Alpha herpesviruses and especially the Bovid Herpesvirus type 1 (BHV-1) but distinguished itself from the latter by its host specificity, serological reaction and genomic restriction fragment pattern (RFP). The host specific red deer herpesvirus was tentatively designated Cervid Herpesvirus type 1 (CHV-1). It was concluded that CHV-1 seropositive deer can be a threat to red deer farming, while in cattle the infection may only cause minor inconvenience through interference with the serological IBR diagnosis.     

Characterization of shiga toxin-producing Escherichia coli strains isolated from calves in Poland

Fecal samples from 67 3–5-months-old calves with diarrhea were screened for the presence of shiga toxin-producing Escherichia coli (STEC). Several accessory virulence factors genes were also tested. Among 192 E.coli isolates tested, 15 (7.6%) were found to harbour the shiga toxin 1 or 2 (stx1 or stx2) genes. The stx2-carrying samples were further subtyped by PCR for the stx2c, stx2d, and stx2e toxin variants. It was shown that stx2-positive bacteria mainly possessed the stx2c shiga toxin type gene. The enterohemolysin (hlyA) and intimin (eae) genes were found in seven (46.7%) STEC strains whereas the cytotoxic necrotizin factor 1 and 2 or the P fimbrial genes were detected in two isolates only. This study confirmed that calves are a reservoir of STEC strains (with all pathogenicity genes) that may be virulent for humans.     

A serological study of canine herpesvirus-1 infection in a population of breeding bitches in Norway

Background

Canine herpesvirus-1 (CHV1) causes a fatal hemorrhagic disease in neonatal puppies and is associated with infertility in female dogs. This study was conducted to assess the status of CHV1 infection in bitches in proestrus or estrus and to investigate possible risk factors by a detailed questionnaire. Blood samples were collected from healthy bitches (n = 193) not vaccinated against CHV1, aged one year or older and admitted for estrus control to the Canine Reproductive Clinical Unit, Norwegian School of Veterinary Science. The serum samples were analysed by immunoperoxidase monolayer assay and serum titers were recorded as the reciprocal value of the highest dilution producing specific cell staining.

Results

Altogether, 85.5% of the dogs had CHV1 titers ≥ 80 and were classified as positive. Mean age for dogs included in the study was 4.2 years (95% CI 4.0-4.5), and there was no difference in age between seronegative dogs vs seropositive dogs. When grouping the seropositive dogs into three categories according to the magnitude of the titer, a total of 38.8% of the bitches displayed a weakly positive titer of 80, 44.8% had moderately positive titers of 160 or 320 and 16.4% of the dogs fell into the strongly positive category with titer of ≥640. No association was demonstrated when comparing CHV1 antibody titers to fertility parameters such as previous matings, pregnancies, whelpings, puppies born or condition of puppies. Further, there was no difference in seroprevalence between bitches that had been abroad for a period of time and dogs only living within a Norwegian environment. Samples from dogs collected in summer and fall displayed moderate to high antibody titers indicating recent infection with CHV1. Season, previous birth, and participation in competitions/shows explained 67-78% of the variation in antibody titer.

Conclusions

This study demonstrates that CHV1 infection is common in breeding bitches in the eastern part of Norway. Associations with putative risk factors were not identified. However, season, previous whelping, and participation in competitions/shows explained 67-78% of the variation in antibody titer.     

Differential expression of pro-inflammatory and anti-inflammatory cytokines during experimental infection with low or high virulence bovine viral diarrhea virus in beef calves

The objective was to compare the mRNA expression of pro-inflammatory (TNF-α, IL-1β, IFN-γ, IL-2, IL-12, IL-15) and anti-inflammatory (IL-4, IL-10, TGF-β) cytokines, after experimental infection with low or high virulence noncytopathic (ncp) bovine viral diarrhea virus (BVDV). Thirty BVDV-naïve, beef calves were intranasally inoculated with low (LV; n = 10, SD-1) or high (HV; n = 10, 1373) virulence ncp BVDV or with BVDV-free cell culture medium (Control, n = 10). Calves were euthanized on day 5 post-inoculation, and tracheo-bronchial lymph node and spleen samples were collected for mRNA expression through quantitative-RT-PCR. mRNA levels of pro-inflammatory (TNF-α, IL-1β, IL-2, IFN-γ) and anti-inflammatory (IL-4 and IL-10) cytokines were up-regulated in tracheo-bronchial lymph nodes of HV, but not in LV, compared to the control group (P < 0.05). IL-12 mRNA level was up-regulated in tracheo-bronchial lymph nodes of both LV and HV groups (P ≤ 0.05). A significant up-regulation of IL-15 mRNA was observed in tracheo-bronchial lymph nodes for LV calves (P < 0.002), but not for HV calves. Experimental inoculation with BVDV-2 1373 stimulated significant mRNA expression of pro-inflammatory and anti-inflammatory cytokines. In contrast, inoculation with BVDV-1a SD-1 only resulted in up-regulation of IL-12 and IL-15 mRNA, which is associated with activation of macrophages and NK cells during innate immune response.     

2009年我国猪群中猪圆环病毒2型感染情况调查

为了解我国猪群中猪圆环病毒2型（Porcine circovirustype2,PCV2）的感染情况,分析感染与猪年龄的关系,本试验于2009年在我国28个省市的71个中小规模场、22个屠宰场和62家散养户采集了2905份猪血清样品,用PCR法对PCV2进行检测。结果显示,检出阳性血清429份,阳性率为14．8％。在被调查的场／P中,86．4％屠宰场、52．1％中小规模场和58．1％散养户为PCV2感染阳性,其中48．6％的PCV2阳性中小规模场的群阳性率低于10％。分析中小规模场PCV2感染情况和猪年龄之间的关系发现,在5个年龄组中,2～4周龄组未检出PCV2感染,5周龄以上各组均检出PCV2感染,其中11～14周龄组和15～26周龄组阳性率较高,高于5～7周龄组和8～10周龄组。     

一例猪瘟与猪圆环病毒2型混合感染的诊治

在生猪养殖过程中,多种病原混合感染的情况较为常见,并这种混合感染也导致传统的临床诊断容易造成误诊或漏诊,继而延误诊断治疗从而造成经济损失.2020年8月初,孟连县某养猪场保育猪群零散发病,临床主要表现为发热、咳喘、打堆、被毛凌乱无光泽、局部皮肤发绀、消瘦、饮食欲下降、生长滞缓,个别猪只伴便秘和腹泻交替.病理剖检变化显示...     

Nucleotide sequence homology to bovine viral diarrhea virus 2 (BVDV 2) in the 5′ untranslated region of BVDVs from cattle with mucosal disease or persistent infection in Japan

Cytopathogenic and non-cytopathogenic bovine viral diarrhea viruses (BVDVs) were isolated from cattle with mucosal disease or persistent infection in Japan. These isolates were compared for antigenic properties by cross-neutralization tests with Japanese reference strains of BVDV belonging to classical type 1. Significantly low cross-reactivity to reference strains was noted, indicating the viruses to possibly represent a new serotype in Japan. Thus, to determine the genotype of the isolates, nucleotide sequences of the 5′ untranslated region were determined and compared with those of previously reported BVDV 1 and 2. The isolates were clearly shown to belong to BVDV 2, not to BVDV 1.     

Bovine cysticercosis in Denmark. A study of possible causes of infection in farms with heavily infected animals

Epidemiological studies were made on 14 farms from which, during a 2 year period, 38 cattle had been condemned at slaughter, due to massive infections with Cysticercus bovis. By on-site investigations and interviews, attempts were made to identify the transmission routes of Taenia saginata eggs from human faeces into the environment and further on to cattle. The most frequent sources of infection were found to be sludge from septic tanks illegally applied on pasture or crops, in some cases after having been mixed with animal slurry. Animals in permanently housed herds were infected through the fodder or by contamination of the indoor environment by such slurry containing Taenia eggs. Other herds were infected by grazing pastures in close proximity to municipal sewage treatment plants. In contrast to earlier Danish observations, application on farmland of sewage sludge from municipal treatment plants was not involved in any of the reported outbreaks. This apparent change coincides with the implementation of more restrictive legislation for the agricultural use of sewage sludge in Denmark.     

A study of outbreaks of Aujeszky's disease in cattle. II. Further investigations on the routes of infection.

The probable routes of infection in 29 outbreaks of Aujeszky’s disease in cattle are discussed in the light of virological and epidemiological data, given in a preceding paper, and of histories of the individual outbreaks given in the present paper. The view was substantiated that anterior pruritus is mostly associated with infection by the respiratory route. In outbreaks with posterior pruritus the route of infection appeared to be a question of a more complex nature. With reference to cases examined later, it is concluded that perineal pruritus is often associated with vaginal infection. In a few cases there was evidence of virus transmission by man. Three cases with pruritus on a hind leg were suggestive of an alimentary infection. In many outbreaks with posterior pruritus, the route of infection remained obscure.     

Distinct fixation of defined amounts of complement by the Brucella abortus antigen and bovine antibodies under different incubation conditions in the CFT

Different times and temperatures of the 1st phase incubation of the complement fixation test (CFT) were used. It was found that a similar decrease in complement (C′) activity occurred after 2 h at 37°C, after 8 h at 20°C and after 18 h at 4°C. Simultaneously, in the same periods a double increase in standard serum titre at 4 and 20°C was noted in comparison with titre at 37°C. This increase of sensitivity of the CFT at 4 and 20°C appeared to be a simulating one and resulted from the different pattern of reaction in each temperature in the block titration of antigen. The positive reactions in the range from the lowest to the highest dilutions of antigen were appearing and increasing and then disappearing in sequence at 4, 20 and 37°C, creating the typical C′ fixation area for each temperature. Similar results were obtained in four different C′ fixation techniques, most frequently used in diagnosis of animal brucellosis. On the basis of our own examination results and literature data the warm and short C′ fixation (37°C, 30 min) was chosen in the standard technique of the CFT used in routine diagnostic survey for animal brucellosis in Poland.     

Change in interleukin 2 production by lymphocytes during maturation of young cats

Lymphocytes from four specific-pathogen free cats were tested for their interleukin 2 activity every week beginning when the cats were 12 weeks old and ending when they were 26 weeks old. Lymphocytes from cats 20 weeks old released significantly more interleukin 2 than those obtained from these cats at earlier ages when stimulated with calcium ionophore A23187 and phorbol myristate acetate. The change of interleukin 2 levels with maturation of young cats may represent an important difference in their level of defense to infections with various pathogens.     

A comparative study of the effects of intramuscular administration of gonadorelin,mating and intrauterine infusion of either raw seminal plasma or seminal plasma purified β‐NGF on luteal development in llamas

The aim of this study was to compare the effect of the intramuscular administration of 50 μg of gonadorelin acetate versus natural mating, intrauterine infusion (i.u.) of a physiological relevant dose of either raw llama seminal plasma (SP) or purified beta‐nerve growth factor from seminal origin (spβ‐NGF) on ovulation rate and corpus luteum (CL) development and function in llamas. Females with a follicle (≥8 mm) were assigned to groups: (i) i.m. administration of 50 μg of gonadorelin acetate (GnRH; positive control; n = 4); (ii) single mating (mating; n = 6); (iii) i.u. infusion of 4 ml of llama SP (SP; n = 4); or (iv) i.u. infusion of 10 mg of spβ‐NGF contained in 4 ml of PBS (phosphate‐buffered saline) (spβ‐NGF; n = 6). Ovaries were examined by power Doppler ultrasonography at 0, 1, 3, 6, 12 and 24 hr after treatment to determine preovulatory follicle vascularization area (VA), and additionally every 12 hr until Day 2 (Day of treatment = Day 0) to determine ovulation. Afterwards, ovaries were examined every other day until Day 8 to evaluate CL diameter and VA. Blood samples were collected on Days 0, 2, 4, 6 and 8 to determine plasma progesterone (P4) concentration. Ovulation rate did not differ (p = .7) among groups, but treatment affected (p < .0001) preovulatory follicle VA. Neither treatment administration nor treatment by time interaction affected (p ≥ .4) CL diameter, VA and plasma P4 concentration. Mating tended (p = .08) to increase CL VA when compared to the seminal plasma group by Day 8. Intrauterine administration of seminal plasma or spβ‐NGF does not increase CL size and function when compared to i.m. GnRH treatment, suggesting that the administration route of spβ‐NGF influences its luteotrophic effect in llamas.