Viral Diseases of the Fetus

Bovine viral diarrhea virus (BVDV) is one of the most commonly encountered and economically important pathogens of cattle in North America. Since the mid-20th century, BVDV has been recognized as a significant cause of disease of the gastrointestinal system. The impact of BVDV on reproduction was not perceived for another 30 years, when the occurrence of persistent infection in imunotolerant cattle was described. BVDV infections may occur in cattle as acute illness- that is, bovine viral diarrhea (BVD)-or as a generally chronic condition-mucosal disease. When susceptible regnant cattle are infected with BVDV, transplacental infections usually occur. Transplacental infections may lead to embryonic or fetal death and abortion, to developmental defects of organs, or to development of immunotolerance and establishment of persistent Infections. Acute BVDV infections contribute, through inmunosuppression, to causing multifactorial diseases, such as diseases of the respiratory and enteric tracts in susceptible calves

Simplified Method for Efficient Intravascular Inoculation of Chicken Embryos

The simple syringe-stabilizer unit described in this note provides a means for rapid intravascular inoculation of embryonated chicken eggs with minimal embryonic death from vascular trauma

In Vitro Expression of Full-Length and Truncated Bovine Respiratory Syncytial Virus G Proteins and Their Antibody Responses in BALB/c Mice

Bovine respiratory syncytial virus (BRSV) is a primary cause of lower respiratory tract disease in calves. Protection is incomplete following vaccination or natural infection, as re-infections are common. The objectives of this study were to create plasmid DNA constructs encoding the full-length, secreted, or conserved region of the BRSV G glycoprotein, and to compare and evaluate their expression in cell culture and potential to induce antibody responses in BALB/c mice. Transfection of COS-7 cells with plasmid DNA resulted in expression of the BRSV G region from each of the plasmid DNA constructs. Following inoculation of BALB/c mice with plasmid DNA, a significant and equivalent anti-BRSV G IgG response was elicited to the full-length and truncated BRSV G proteins. These constructs may be used to study host pathological and immunological responses

Effectiveness of Composting as a Biosecure Disposal Method for Porcine Epidemic Diarrhea Virus (PEDV)-Infected Pig Carcasses

Porcine epidemic diarrhea virus (PEDV) is an enteric disease of swine that has emerged as a worldwide threat to swine herd health and production. Substantial research has been conducted to assess viability of the virus on surfaces of vehicles and equipment, in feed and water, and on production building surfaces, but little is known about the persistence in PEDV-infected carcasses and effective disposal methods thereof. This study was conducted to quantify the persistence of PEDV RNA via quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) at various time-temperature combinations and in infected piglet carcasses subjected to composting. Although this method does not distinguish between infectious and noninfectious virus, it is a rapid and sensitive test to evaluate materials for evidence of virus genome

Experimental infection of conventional nursing pigs and their dams with \u3ci\u3ePorcine deltacoronavirus\u3c/i\u3e

Porcine deltacoronavirus (PDCoV) is a newly identified virus that has been detected in swine herds of North America associated with enteric disease. The aim of this study was to demonstrate the pathogenicity, course of infection, virus kinetics, and aerosol transmission of PDCoV using 87 conventional piglets and their 9 dams, including aerosol and contact controls to emulate field conditions. Piglets 2–4 days of age and their dams were administered an oronasal PDCoV inoculum with a quantitative real-time reverse transcription (qRT)-PCR quantification cycle (Cq) value of 22 that was generated from a field sample having 100% nucleotide identity to USA/Illinois121/2014 determined by metagenomic sequencing and testing negative for other enteric disease agents using standard assays. Serial samples of blood, serum, oral fluids, nasal and fecal swabs, and tissues from sequential autopsy, conducted daily on days 1–8 and regular intervals thereafter, were collected throughout the 42-day study for qRT-PCR, histopathology, and immunohistochemistry. Diarrhea developed in all inoculated and contact control pigs, including dams, by 2 days post-inoculation (dpi) and in aerosol control pigs and dams by 3–4 dpi, with resolution occurring by 12 dpi. Mild to severe atrophic enteritis with PDCoV antigen staining was observed in the small intestine of affected piglets from 2 to 8 dpi. Mesenteric lymph node and small intestine were the primary sites of antigen detection by immunohistochemistry, and virus RNA was detected in these tissues to the end of the study. Virus RNA was detectable in piglet fecal swabs to 21 dpi, and dams to 14–35 dpi

Comparison of the Direct Agglutination and Indirect Hemagglutination Tests in the Determination of Blood Serum Titers to \u3ci\u3eEscherichia coli\u3c/i\u3e Organisms

A comparison of the direct agglutination test and the indirect hemagglutination test for the detection of blood serum antibodies to Escherichia coli organisms indicated that these serological tests were comparable. In some instances the indirect hemagglutination test provided higher endpoint readings. Preparation of the antigens for the indirect hemagglutination test was more time consuming than for the direct agglutination test. Crude extract and purified polysaccharides were comparable as red blood cell sensitizing agents

Long-Term Clinicopathological Characteristics of Alpacas Naturally Infected with Bovine Viral Diarrhea Virus Type Ib

Background: Substantial bovine viral diarrhea virus (BVDV)-related production losses in North American alpaca herds have been associated with BVDV type Ib infection. Objectives: To classify and differentiate the long-term clinicopathological characteristics of BVDV type Ib infection of al- paca crias, after natural virus exposure. We hypothesized that persistently infected (PI) alpacas specifically demonstrate growth retardation, clinicopathological evidence of opportunistic infections, and early mortality. Animals: Thirty-five crias naturally exposed to BVDV (18 acute, 3 chronic, 14 PIs), and 19 healthy cohort controls of 5 northeastern alpaca farms were prospectively evaluated over 2 years (September 2005–September 2008). Methods: Observational cohort-control study. Results: Chronically (viremia 43 weeks) and PI crias demonstrated significantly lower birth weights, decreased growth rates, anemia, and monocytosis compared with control animals. Common clinical problems of PI alpacas included chronic wasting, diarrhea, and respiratory disease. Median survival of PI alpacas that died was 177 days (interquartile range, 555) with a case fatality rate of 50% within 6 months of life. Transplacental infection was confirmed in 82% (9/11) of pregnant females on 1 farm, resulting in the birth of 7 PI crias (7/10 deliveries; 1 animal was aborted). Mean gestation at the beginning and end of BVDV exposure was 64 and 114 days, respectively. Conclusions and Clinical Importance: Natural BVDV type 1b infection during early pregnancy resulted in a high incidence of PI offspring. Although PI alpacas may have distinct clinical characteristics, verification of persistent viremia in the absence of endogenous, neutralizing antibodies is essential to differentiate persistent from chronic infection

Influence of bovine respiratory syncytial virus F glycoprotein \u3ci\u3eN\u3c/i\u3e-linked glycans on in vitro expression and on antibody responses in BALB/c mice

Bovine respiratory syncytial virus (BRSV) is an etiological component of the bovine respiratory tract disease complex. Infection with BRSV following vaccination, or re-infection following natural infection is common since protection is incomplete. The objectives of this study were to create plasmid DNA constructs encoding single or multiple N-glycosylation-site deletion BRSV fusion (F) proteins, and evaluate their expression in cell culture, and potential to induce anti-BRSV F antibody responses in BALB/ c mice. Four plasmid DNAs were constructed, each encoding 1-4 N-glycosylation-site deletions: Gly4, Gly2/4, Gly1/2/4 and Gly1/2/3/4. Each of the N-glycosylation-site deletion BRSV F proteins were expressed in COS-7 cells following transfection with plasmid DNA. Inoculation of BALB/c mice with plasmid DNA, resulted in a significant anti-BRSV F IgG response to the wildtype (WT) F and glycosylation-site deletion protein Gly2/4. Gly2/4 elicited a higher antibody titer than the fully glycosylated WT F protein. Significant neutralizing antibody titers were detected following immunization with the Gly2/4 plasmid DNA. These glycosylation-site deletion BRSV F proteins will be useful to characterize the effects of glycosylation on immunogenicity in the natural host, and may lead to a new approach for the generation of BRSV vaccines