Molecular specificity of the antibody responses of cattle naturally and experimentally infected with cytopathic and noncytopathic bovine viral diarrhea virus biotypes

The specificity of the humoral IgG response of cattle naturally or experimentally infected with bovine viral diarrhea virus (BVDV) was studied by radioimmunoprecipitation. Serum samples were tested against radiolabeled lysates of cells infected with cytopathic and noncytopathic biotypes of BVDV. A biotype-specific serologic marker was not detected. The specificity of the IgG induced in cows naturally or experimentally infected with either BVDV biotype was essentially the same. A strong IgG response to the 2 glycoproteins (56 to 58 kilodaltons, [kD] and 48 kD) of both biotypes and to the major polypeptides was induced in infected cells: 118 kD and 80 kD by cytopathic BVDV and only 118 kD by noncytopathic BVDV. The most consistent difference among cattle was the presence of IgG specific for the 37-kD polypeptide. Sequential serum sample collection after spontaneous and induced infections with either BVDV biotype did not indicate specific IgG markers for determining infection history. Sera from cattle with a confirmed diagnosis of mucosal disease and lacking neutralizing antibodies to BVDV usually lacked (greater than 80%) nonneutralizing BVDV-specific IgG. One animal had substantial amounts of IgG to the 80-kD polypeptide. Other cattle had less readily detectable amounts of IgG specific for 80-kD or 37-kD viral polypeptides.     

Quantification of viral ribonucleic acid in plasma of cats naturally infected with feline immunodeficiency virus

OBJECTIVE: To assess plasma viral RNA concentration in cats naturally infected with feline immunodeficiency virus (FIV). ANIMALS: 28 FIV-infected cats. PROCEDURE: Cats were categorized into 1 of the 3 following stages on the basis of clinical signs: asymptomatic (nonclinical) carrier (AC; n = 11), acquired immunodeficiency syndrome-related complex (ARC; 9), or acquired immunodeficiency syndrome (AIDS; 8). Concentration of viral RNA in plasma (copies per ml) was determined by use of a quantitative competitive polymerase chain reaction (QC-PCR) assay. Total lymphocyte count, CD4+ cell and CD8+ cell counts, and the CD4+ cell count-to-CD8+ cell count ratio were determined by use of flow cytometry. RESULTS: Plasma viral RNA concentration was significantly higher in cats in the AIDS stage, compared with cats in AC and ARC stages. Most (5/7) cats in the AIDS stage had low total lymphocyte, CD4+ cell, and CD8+ cell counts. CONCLUSIONS AND CLINICAL RELEVANCE: Concentration of plasma viral RNA is a good indicator of disease progression in FIV-infected cats, particularly as cats progress from the ARC to the AIDS stage. Determination of CD4+ and CD8+ cell counts can be used as supportive indicators of disease progression.     

Haematogenous spread of Sporothrix schenckii in cats with naturally acquired sporotrichosis

The recovery of Sporothrix schenckii from blood samples is rare, and the diagnosis of systemic sporotrichosis is usually made at necropsy. In this report, S schenckii was isolated from two or more internal organs of nine necropsied cats with naturally acquired sporotrichosis. Haematogenous spread was demonstrated in vivo by the isolation of S schenckii from the peripheral blood of 17 (n = 49, 34.4 per cent) cats. Feline leukaemia virus (FeLV) was not detected, and co-infection with feline immunodeficiency virus (FIV), observed in nine cases (n = 43, 20.9 per cent), apparently did not affect the isolation of S schenckii from peripheral blood or from the internal organs.     

Response of cattle persistently infected with noncytopathic bovine viral diarrhea virus to vaccination for bovine viral diarrhea and to subsequent challenge exposure with cytopathic bovine viral diarrhea virus

Nine steers persistently infected with noncytopathic bovine viral diarrhea (BVD) virus were allotted into 3 groups (3 cattle/group). Cattle in group A were vaccinated with a modified-live BVD virus vaccine of porcine cell origin, cattle in group B with a modified-live BVD virus vaccine of bovine cell origin, and cattle in group C with a killed BVD virus vaccine of bovine cell origin. Detrimental effects due to vaccination were not seen. Six weeks after vaccination, the steers were challenge exposed with a cytopathic BVD virus. All steers developed mucosal disease after challenge exposure, produced antibodies that neutralized various isolates of BVD virus, and remained persistently infected until death. Steers given killed virus vaccine had a minimal neutralizing-antibody response and developed mucosal disease as quickly as reported for challenge-exposed, nonvaccinated, persistently infected cattle. Steers given modified-live virus vaccines had higher neutralizing-antibody response and longer intervals from challenge exposure to development of mucosal disease. The specificity of the neutralizing-antibody response differed between groups of vaccinated cattle.     

Humoral immune response to immediate-early protein of pseudorabies virus in swine with induced or naturally acquired infection

Pseudorabies virus (PRV) immediate-early (IE) protein is a nonglycosylated polypeptide localized in the nuclei of infected cells. The IE protein is a regulatory protein that is only synthesized during viral replication and is presented to the immune system of PRV-infected swine. Antibodies to the IE protein were demonstrated in swine with induced or naturally acquired infection. However, antiserum raised against purified IE protein could not neutralize PRV in vitro.     

Correlation of serum concentration of alpha 1-acid glycoprotein with lymphocyte blastogenesis and development of experimentally induced or naturally acquired hepatic abscesses in cattle.

Changes in serum alpha 1-acid glycoprotein (alpha 1AG) concentration in cattle with hepatic abscesses were observed, and function of alpha 1AG was evaluated, particularly its influence on cellular immune response. Test cattle (n = 4) were inoculated with Fusobacterium necrophorum, control cattle (n = 2) were inoculated with inactivated bacteria, and naturally affected cattle (n = 11) were found in a slaughterhouse. Determination of alpha 1AG was made by use of a single radial immunodiffusion method. The action on lymphocyte blastogenesis was determined by [3H]thymidine incorporation. Cultured lymphocytes from healthy cattle were treated with variable concentrations of alpha 1AG purified from serum obtained from cattle with hepatic abscesses and suppression of blastogenesis stimulated by each of 3 mitogens was measured. In cattle with experimentally induced abscesses, serum alpha 1AG concentration increased for 7 to 10 days after F necrophorum inoculation, its change being parallel to that of sialic acid. High concentration of alpha 1AG was found in naturally affected cattle and was highly correlated to sialic acid concentration. Suppression of lymphocyte blastogenesis in cattle with experimentally induced hepatic abscesses was highly correlated to serum alpha 1-AG concentration.     

Serological comparison of cytopathogenic and non-cytopathogenic bovine viral diarrhea-mucosal disease viruses isolated from cattle with mucosal disease

Ten cattle that died with mucosal disease were examined for bovine viral diarrhea-mucosal disease (BVD-MD) viruses. Both cytopathogenic (CP) and non-cytopathogenic (NCP) BVD-MD viruses were isolated concomitantly from 9 of them, and only a CP virus was recovered from the other. Then each pair of CP and NCP viruses was compared serologically by a serum neutralization test. Each pair of CP and NCP viruses from the same cattle was found to be serologically indistinguishable, although a minor antigenic difference was observed among the groups of the paired viruses. These results seem to support the hypotheses that mucosal disease occurs in persistently infected cattle which were induced by in utero infection with NCP virus when they are superinfected with CP virus, and the antigenic homology in CP and NCP BVD-MD viruses may be an important factor in the pathogenesis of the disease.     

Immunologic profiles of cats with persistent, naturally acquired feline leukemia virus infection

Several immunologic responses were measured in 13 healthy cats with naturally acquired, persistent feline leukemia virus (FeLV) viremia from 4 multiple-cat households and were compared with responses from 28 of their healthy, non-FeLV-viremic housemates. Significant differences (P = less than 0.05) were not observed between results of FeLV-viremic and nonviremic cats for peripheral blood leukocyte or lymphocyte count, percentage of peripheral blood mononuclear cells able to form rosettes with guinea pig RBC or with antibody- and complement-coated sheep RBC, lymphocyte proliferative response to concanavalin A or pokeweed mitogen, or serum immunoglobulin G concentration. Seemingly, persistent FeLV viremia, when naturally acquired, may exist for some time without lymphopenia or a marked loss of mitogen-induced lymphocyte proliferation.     

Bovine viral diarrhea virus: biotypes and disease.

Bovine viral diarrhea virus continues to produce significant economic losses for the cattle industry and challenges investigators with the complexity of diseases it produces and the mechanisms by which it causes disease. This paper updates and attempts to clarify information regarding the roles of noncytopathic and cytopathic bovine viral diarrhea viruses in persistent infections and mucosal disease. It also covers, in brief, what is known of the new diseases: thrombocytopenia and hemorrhagic disease, and a disease resembling mucosal disease that is apparently caused solely by noncytopathic virus. Although a good understanding of the roles of the 2 biotypes in the production of persistent infections and the precipitation of mucosal disease has been obtained, there are still unanswered questions regarding the origin of cytopathic viruses and the mechanism by which they cause pathological changes in cells. It is apparent, however, that cytopathic bovine viral diarrhea viruses arise by mutation of noncytopathic viruses, and it is known that p80 is the marker protein for cytopathic viruses. The previous distinction between mild bovine viral diarrhea and fatal mucosal disease has been eroded with the emergence of new virulent bovine viral diarrhea viruses. The new diseases pose a threat to the cattle industry and present a new challenge for investigators. Index Veterinarius (1984-1994) and Medline (1985-1994) databases and personal files updated since 1987 from BIOSIS Previews and Biosciences Information Services were used to search the literature.     

Surveillance for persistent bovine viral diarrhea virus infection in four artificial insemination centers

Four large bovine artificial insemination centers implemented a program of surveillance of resident and newly acquired bulls for persistent bovine viral diarrhea virus infection. Infection was identified in 12 of 1,538 bulls. Several clinical abnormalities, including acute and chronic mucosal disease, were evident among the persistently infected bulls. Semen produced by such bulls consistently contained bovine viral diarrhea virus, and such contamination was not always accompanied by diminished seminal quality. Infected bulls were detected by means of virus isolation tests performed on blood specimens, but not by use of serologic testing. Ten of the 12 persistently infected bulls were results of embryo transfer. Virologic surveillance of breeding herds, artificial insemination and embryo transfer centers, and the cattle trade is necessary to prevent spread of this virus by modern cattle breeding practices. Attention is also necessary to prevent contamination by this virus of the fluids used for recovery, in vitro manipulation, and transfer of bovine embryos.     

Experimental infection of calves with bovine viral diarrhea virus genotype II (NY-93).

To ascertain the virulence of bovine viral diarrhea virus (BVDV) genotype II, isolate NY-93 was inoculated intranasally into 3 calves, 2 of which were treated with a synthetic glucocorticoid prior to and after virus inoculation. Anorexia, fever (up to 42 C), dyspnea, and hemorrhagic diarrhea developed 6 days after intranasal inoculation with BVDV NY-93. The condition of all calves deteriorated further until the end of the study on day 14 postinoculation. The most significant postmortem macroscopic changes in all calves were limited to the gastrointestinal tract and consisted of moderate to severe congestion of the mucosa with multifocal hemorrhages. Microscopic lesions found in the gastrointestinal tract were similar to those observed in mucosal disease, including degeneration and necrosis of crypt epithelium and necrosis of lymphoid tissue throughout the ileum, colon, and rectum. The basal stratum of the epithelium of tongue, esophagus, and rumen had scattered individual necrotic cells. Spleen and lymph nodes had lymphocytolysis and severe lymphoid depletion. Severe acute fibrinous bronchopneumonia was present in dexamethasone-treated calves. Abundant viral antigen was detected by immunohistochemistry in the squamous epithelium of tongue, esophagus, and forestomachs. BVDV antigen was prominent in cells of the media of small arteries and endothelial cells. The presence of infectious virus in tissues correlated with an absence of circulating neutralizing antibodies. These findings highlight the potential of BVDV genotype II to cause severe disease in normal and stressed cattle.     

Distribution of bovine virus diarrhoea viral antigens in the central nervous system of cattle with various congenital manifestations.

Distribution of bovine viral diarrhoea virus (BVDV) antigens in the central nervous system (CNS) of 26 cattle persistently BVDV infected, 11 cattle with mucosal disease (MD), and 32 calves with congenital brain malformations was studied using monoclonal antibodies against BVDV epitopes. In persistently infected cattle and in cattle with MD, a widespread infection of neurons was present. Predilection sites for BVDV antigens were the cerebral cortex and the hippocampus. In calves with congenital encephalopathies, viral antigen-containing neurons could only be detected in the CNS of four animals. From the topographical distribution of BVDV antigens in these four postnatal cases with end-stage lesions, no conclusions could be drawn concerning the pathogenesis of BVDV-induced encephalopathies.     

Detection of bovine viral diarrhoea virus in specimens from cattle in South Africa and possible association with clinical disease

Studies covering all aspects of bovine viral diarrhoea virus (BVDV) have been conducted in several countries in Europe, Asia and America. In southern Africa, more information is required about the nature of BVDV infection, the prevalence of different strains and the economic importance of the disease. The presence of BVDV in southern Africa has been known since the early 1970s through serological surveys but few reports confirming its presence by virus isolation and correlation with clinical disease are available. Specimens (n = 312) collected in 1998/99, from live and dead cattle from different farming systems, were obtained from private practitioners, feedlot consultants and abattoirs throughout the country. Specimens (n = 37) from African buffaloes (Syncerus caffer) in the Kruger National Park were also included. All specimens were processed for virus isolation in cell culture with confirmation by means of immunofluorescent antibody tests and some also by means of an antigen capture ELISA. BVDV was isolated from 15 (4.7%) cattle and were all noncytopathic biotypes. BVDV was not detected in 37 lymph nodes obtained from buffaloes in the Kruger National Park. Of the clinical signs in cattle from which virus were isolated, respiratory signs was the most frequent (10/15), followed by diarrhoea (5/15). Abortion, congenital malformations, haemorrhagic diarrhoea and poor growth were also included as criteria for selection of animals for specimen collection, but no BVD viruses were isolated from cattle manifesting these clinical signs.     

Histopathologic patterns of nephropathy in naturally acquired canine visceral leishmaniasis

Although the nephropathy of visceral leishmaniasis (VL) is known both in humans and dogs, histopathologic alterations have not been thoroughly studied. We examined renal alterations in 55 dogs with naturally acquired VL compared with five noninfected dogs from an endemic area in northeastern Brazil. Glomerulonephritis was found in 55 dogs, interstitial alterations in 53 dogs, and tubular changes in 43 dogs with VL. The glomerular alterations found were minor glomerular abnormalities (n = 8, 14.5%), focal segmental glomerulosclerosis (n = 10, 18.2%), mesangial proliferative glomerulonephritis (n = 17, 32.7%), membranoproliferative glomerulonephritis, (n = 18, 30.9%), crescentic glomerulonephritis (n = 1, 1.8%), and chronic glomerulonephritis (n = 1, 1.8%). Morphometric and ultrastructural studies complemented the analysis. The five control animals exhibited no glomerular alterations. The glomerular lesions were related to functional alterations. Considering that the alterations of canine and human nephropathy in VL are very similar, the data obtained in this study constitute an important contribution to the understanding of canine and human VL nephropathy.     

Hemorrhagic syndrome-like disease in calves with bovine viral diarrhea and mucosal disease complex

BACKGROUND: Bovine viral diarrhea virus (BVDV) infection is one of the causes of hemorrhagic diathesis in cattle but there have been limited field studies about that condition. HYPOTHESIS: To identify the cause of hemorrhagic diathesis in calves and describe its clinical findings. ANIMALS: Five calves from a farm with 150 dairy cows. METHODS: Clinical examination of the calves was performed. After blood samples were obtained from 2 calves, whole blood, sera, and leukocyte samples were used for hematologic and hemostatic examinations, neutralization tests, virus isolation, and viral genome sequencing. RESULTS: The calves had moderate pyrexia, dullness, serous or mucous nasal discharge, and petechial and ecchymotic hemorrhages on mucosal surfaces. Severe thrombocytopenia and anemia were identified on hematologic examinations. All calves died within 10 days of the onset of clinical signs. Virologic examinations identified BVDV as the causative agent of the disease. CONCLUSIONS AND CLINICAL IMPORTANCE: This paper identifies a hemorrhagic syndrome-like disease in calves with bovine viral diarrhea and mucosal disease complex in Turkey.     

Comparative virulence of isolates of bovine viral diarrhea virus type II in experimentally inoculated six- to nine-month-old calves

OBJECTIVE: To determine the comparative virulence of 5 isolates of bovine viral diarrhea virus (BVDV) type II by inoculating 6- to 9-month-old beef calves with isolates originating from the tissues of cattle affected with naturally occurring, transient, acute, nonfatal infections or naturally occurring, peracute, fatal infections. ANIMALS: 22 calves that were 6 to 9 months old. PROCEDURE: The study used BVDV isolates 17011, 713, and 5521 that originated from fetuses aborted from cows with transient, nonfatal, acute BVDV infections and isolates 23025 and 17583 that originated from the tissues of cattle with peracute, fatal BVDV infections. Calves were allotted to 6 groups (1, mock-infected control calves [n = 2]; 2, inoculated with BVDV 17011 [4]; 3, inoculated with BVDV 713 [4]; 4, inoculated with BVDV 5521 [4]; 5, inoculated with BVDV 23025 [4]; and 6, inoculated with BVDV 17583 [41]. Rectal temperatures and clinical signs of disease were recorded daily. Total and differential WBC and platelet counts were performed. Histologic examination and immunohistochemical analysis were conducted to detect lesions and distribution of viral antigens, respectively. RESULTS: Calves inoculated with BVDV 23025 or 17583 developed more severe clinical signs of disease (fever and diarrhea), more severe lymphopenia, and more severe lesions (alimentary epithelial necrosis, lymphoid depletion, and BVDV antigen deposition in lymphatic tissues), compared with calves inoculated with BVDV 713, 5521, or 17011. CONCLUSIONS AND CLINICAL RELEVANCE: Relative severity of experimentally induced infections corresponded to severity of clinical signs of naturally occurring infections with respective BVDV isolates.     

Detection and comparison of nitric oxide in clinically healthy horses and those with naturally acquired strangulating large colon volvulus

The objective of the study was to determine whether nitric oxide (NO) is present in clinically healthy horses (control) under basal conditions, and if it increases secondary to naturally acquired strangulating large colon volvulus (affected). Eleven affected horses and 10 controls were studied. Jugular venous blood, abdominal fluid, and urine were collected. The NO concentrations were standardized to the creatinine concentration in the respective samples. A biopsy specimen collected from the large colon pelvic flexure at surgery was divided into subsections for processing for inducible nitric synthase (iNOS) and nitrotyrosine (NT) immunohistochemical staining and reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemical staining. There were no significant differences in plasma, abdominal fluid, or urine NO concentrations between affected and control horses. There was a significant decrease in submucosal arteriolar and venular endothelium, submucosal plexus, mucosal leukocyte, mucosal and musclaris vasculature, and myenteric plexus NADPH diaphorase staining in affected versus control horses. There was a significant increase in iNOS staining in mucosal leukocytes and vasculature in affected versus control horses. Other than a greater number of positively stained mucosal leukocytes in affected horses, there were no significant differences between affected and control horses for NT staining. The presence of NADPH diaphorase staining in the endothelium and submucosal neurons suggests endothelial and neuronal NOS are present under basal conditions in the large colon of horses. Increased iNOS and NT staining in mucosal leukocytes of affected horses suggests involvement of the NO pathway in large colon volvulus. The reasons for the lack of a significant difference in plasma, abdominal fluid, and urine NO concentrations between affected and control horses are unknown.     

Monoclonal antibody-based immunohistochemical detection of bovine viral diarrhea virus in formalin-fixed, paraffin-embedded tissues.

Thirty-two monoclonal antibodies directed against epitopes on bovine viral diarrhea virus proteins and glycoproteins were tested for immunohistochemical reactivity with bovine viral diarrhea virus in formalin-fixed and paraffin-embedded tissues from 45 cases of bovine viral diarrhea virus-associated mucosal disease. Only one antibody, designated 15C5, which reacts with the 48-kD glycoprotein of bovine viral diarrhea virus, detected an epitope preserved in these specimens. Monoclonal antibody 15C5 and a polyclonal antibody to bovine viral diarrhea virus successfully detected bovine viral diarrhea viral antigens in 44/45 cases of mucosal disease and did not react with formalin-fixed tissues from 30 uninfected cattle. Monoclonal antibody-based immunohistochemical detection of bovine viral diarrhea virus is routinely fixed tissue specimens has advantages over other currently available techniques in terms of the convenience of specimen submission, the relative ease of method standardization, and the rapidity of the test, and by enabling identification of the virus in association with specific tissues, cell types, and histologic lesions.     

Investigation of an outbreak of mucosal disease in a beef cattle herd in southwestern Saskatchewan.

This study describes the epidemiological investigation of an outbreak of mucosal disease that occurred on a ranch in southwestern Saskatchewan. Over a six-month period during the fall and winter of 1991-1992, in a herd of 515 beef cattle and 96 bison, 20 yearling cattle from a group of 105 housed in one feedlot pen died from mucosal disease. A further eight yearlings were slaughtered for salvage because they were at risk of dying from mucosal disease. Mucosal disease mortalities were the first observed evidence of fetal infections with bovine viral diarrhea virus in this herd. Animals that died from mucosal disease exhibited signs of ill thrift prior to death. Deaths from mucosal disease were confined to the progeny of one herd of beef cows. Following an outbreak of fetal infection with bovine viral diarrhea virus during 1989-1990, at least 28 (22%) of the 128 calves born from this herd of cows in the spring of 1990 were persistently infected with bovine viral diarrhea virus. However, only one calf born from this herd in 1991, and five calves born from all herds in 1992 were persistently infected. Of the five persistently infected calves born in 1992, three were born to persistently infected replacement heifers born in 1990. These heifers calved without assistance in 1992, but only one of their calves survived past three days of age, and it was persistently infected. In January 1992, 82% of the total herd had reciprocal antibody titers to bovine viral diarrhea virus of > or = 1024 which suggested a high level of herd immunity to bovine viral diarrhea virus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Apoptosis inhibitors delay the cytopathic effect of bovine viral diarrhoea virus (BVDV)

Based on their action in cell culture, two biotypes of bovine viral diarrhoea virus (BVDV) can be distinguished. The noncytopathic (ncp) BVDV isolated from persistently infected animals cause no visible damage to cultured bovine cells. In contrast, cytopathic (cp) BVDV induces severe damage and apoptosis in cell cultures. Cp BVDV can be isolated from cattle suffering from mucosal disease (MD) and is associated with the severe lesions that primarily affect the gastrointestinal tract. To get an insight into the molecular events during BVDV induced cytopathic effect (CPE), the effect of three chemical reagents (3-aminobenzamide, ascorbic acid and N-acetyl-leucyl-leucyl-methional) with completely different mode of actions in infected cells was analysed. All three substances were able to delay the cytopathic effect induced in permissive bovine cells.