Beef Cattle Salmonellosis: A Study of Oral Salmonella typhimurium and Topical Salmonella newport Inoculations

Cattle are frequently infected with salmonellae by fecaloral transmission or by being fed contaminated animal protein byproducts (40% are reported contaminated in the U.S.). Bothcould propagate salmonellosis in feedlots. Research indicates that stress can induce shedding of salmonellae by asymptomatic carriers. Stress factors associated withsalmonellosis include: transportation, starvation, changes in ration, overcrowding, age, pregnancy, parturition, exertion, anesthesia, surgery, intercurrentdisease, and oral treatment withantibioticsand anthelmintics. In this study, we have attempted to correlate dosage of S. typhimurium inoculumwithdisease, persistence of infection, and environmental contamination. The persistence and spread of S. newport placed on the skin of cattle was also studied

Beef Cattle Salmonellosis: A Study of Oral Salmonella typhimurium and Topical Salmonella newport Inoculations

Cattle are frequently infected with salmonellae by fecaloral transmission or by being fed contaminated animal protein byproducts (40% are reported contaminated in the U.S.). Bothcould propagate salmonellosis in feedlots. Research indicates that stress can induce shedding of salmonellae by asymptomatic carriers. Stress factors associated withsalmonellosis include: transportation, starvation, changes in ration, overcrowding, age, pregnancy, parturition, exertion, anesthesia, surgery, intercurrentdisease, and oral treatment withantibioticsand anthelmintics. In this study, we have attempted to correlate dosage of S. typhimurium inoculumwithdisease, persistence of infection, and environmental contamination. The persistence and spread of S. newport placed on the skin of cattle was also studied

Development of a Sensitive Antibody Detection Method to Bovine Viral Diarrhea Virus (BVDV) Infection

Bovine viral diarrhea virus (BVDV) is a RNA virus and a prototype member of the pestivirus genus in the genetic family Flaviviridae. Due to the rapid growth of BVDV molecular biology in the last 4 yr, our understanding of the genomic organization of BVDV has greatly increased, and a protein encoding map of the BVDV genome has been established. According to this map, it is generally accepted that a glycoprotein, identified as gp116, is the precursor which gives rise to gp62 and gp53 proteins through a proteolytic process. Further protein break down of gp62 yields glycoproteins gp48 and gp25. The order of these genes in the BVDV genome would thus be gp48-gp25-gp53. Based on the serological testing results of cattle to individual BVDV proteins, a strong immune response to glycoproteins gp53 and gp48 has been found. Although considerable literature exists on the diagnosis of BVD disease, the methodologies (virus isolation, serum neutralization, etc.) are either time consuming, expensive, inconsistent, or unsuitable for use in large populations of cattle. Recently, recombinant techniques have found wide application in a second-generation assay for the detection of viral disease infection. We have produced recombinant gp48 in large amounts using these recombinant techniques. The large-scale production of the recombinant gp48 protein provided a convenient and economical source of immunobiologically useful material. This recombinant protein demonstrated great sensitivity and specificity for BVD antibody detection

Development of a Method for the Serological Differentiation Between Animals Either Vaccinated with Killed Virus Vaccine or Infected by Bovine Viral Diarrhea Virus (BVDV)

Bovine viral diarrhea (BVO), caused by the BVO virus, has been recognized in many parts of the world and is considered to have a marked economic impact on the cattle industry. In the U.S. alone, serological surveys indicated that 60 to 80% of the cattle population have antibodies to the virus. There are many strains of bovine viral diarrhea virus (BVOV) which differ in their ability to cause changes in cell culture. Thus, cytopathic and noncytopathic biotypes of BVOV are identified. The cytopathic strains induce a vacuolation of the infected cultured cells, where noncytopathic strains do not. Control of BVOV has been attempted for many years by use of either modified-live or killed virus vaccines. The killed virus vaccine is more commonly used. The modifiedlive virus vaccine is known to cause complications during pregnancy, potentially fetopathogenic effects being a major concern. There is evidence that vaccination of persistently infected cattle with modified-live virus vaccine can result in severe mucosal disease. Oue to the ubiquitous nature of BVOV, producers may find advantages in designing BVO control procedures for a herd to be able to differentiate between cattle that 1) have received modified-live BVO virus vaccination, 2) have received killed BVO virus vaccination, or 3) were naturally infected. This study explored the potential of BVOV protein, p80, to allow differentiation of the above three conditions. The genome of an isolate of a BVOV strain has been sequenced. Encoded within the genome are at least four primary gene products (proteins): p20, gp116, p125, and p133. There is evidence that p125 polypeptide precursor gives rise to p80 polypeptide due to the breakdown of this precursor protein in cells infected with BVOV. The p80 area of the BVOV genome is well conserved in the many BVOV strains that have been isolated

Transmission of Bovine Leukosis Virus

Bovine leukosis virus is an exogenous retrovirus (Retroviridae, Oncovirinae) that infects lymphocytes of cattle. Infection with bovine leukosis virus and the concomitant antibody response are lifelong. Infection can result in several outcomes, including production of antibodies against bovine leukosis virus without other evidence of infection, inversion of the T:B lymphocyte ratio, persistent lymphocytosis, and clinical lymphosarcoma. The prevalence of an infection in a population of animals is the proportion of the group infected at any given time. Surveys have shown the prevalence of bovine leukosis virus infection in cattle populations ranging from 0 to nearly 100%. This wide range of prevalence levels is likely due to variations in risk factors such as husbandry practices, insect vectors, and genetic resistance. For example, prevalence tends to be higher in dairy than beef cattle and in cattle in Southern vs Northern states. The relative importance of the known modes of transmission of bovine leukosis virus has not been established in beef cattle. Also, the economic impact of bovine leukosis virus infection in beef cattle has not been examined. However, the presence of cattle infected with bovine leukosis virus in a herd drastically reduces opportunities to export cattle and/or semen to many countries. Excluding an early transient viremia, the virus locates in lymphocytes as a DNA provirus. Because of its ceil-associated nature, transmission is believed to occur by movement of infected lymphocytes to susceptible animals. Intradermal, subcutaneous, intramuscular, or intravenous inoculation of as little as one microliter of blood or intracutaneous inoculation of 2,500 lymphocytes from an infected animal (equivalent to .5 microliter of blood) results in transmission of bovine leukosis virus. Transmission of an infectious agent in this manner is a form of horizontal transmission. Other means of horizontal transmission have been investigated, including casual contact in common housing; animal husbandry procedures such as dehorning without sanitizing the dehorner between cattle, tattooing with common pliers, rectal palpations with common sleeves, and injections with common needles; and blood feeding arthropods. In addition, transmission from the dam to calf, termed vertical transmission, has also been shown to occur with bovine leukosis virus. The purpose of these studies was threefold: 1) to characterize the bovine leukosis virus status of the U.S. Meat Animal Research Center cattle population, 2) to investigate the extent and significance of vertical transmission of bovine leukosis virus in the U.S. Meat Animal Research Center cow herd, and 3) to investigate the role of specific management practices in horizontal transmission of bovine leukosis virus in the U.S. Meat Animal Research Center cattle herd

Monoclonal Antibodies for Detection of the H7 Antigen of \u3ci\u3eEscherichia coli\u3c/i\u3e

Two murine monoclonal antibodies (MAbs) (2B7 and 46E9-9) reactive with the H7 flagellar antigen of Escherichia coli were produced and characterized. A total of 217 E. coli strains (48 O157:H7, 4 O157:NM, 23 O157:non-H7, 22 H7:non-O157, and 120 non-O157:non-H7), 17 Salmonella serovars, and 29 other gramnegative bacteria were used to evaluate the reactivities of the two MAbs by indirect enzyme-linked immunosorbent assay (ELISA). Both MAbs reacted strongly with all E. coli strains possessing the H7 antigen and with H23- and H24-positive E. coli strains. Indirect ELISA MAb specificity was confirmed by inhibition ELISA and by Western blotting (immunoblotting), using partially purified flagellins from E. coli O157:H7 and other E. coli strains. On a Western blot, MAb 46E9-9 was more reactive against H7 flagellin of E. coli O157:H7 than against H7 flagellin of E. coli O1:K1:H7. Competition ELISA suggested that MAbs 2B7 and 46E9-9 reacted with closely related H7 epitopes. When the ELISA reactivities of the MAbs and two commercially available polyclonal anti-H7 antisera were compared, both polyclonal antisera and MAbs reacted strongly with E. coli H7 bacteria. However, the polyclonal antisera cross-reacted strongly both with non-H7 E. coli and with many non-E. coli bacteria. The polyclonal antisera also reacted strongly with H23 and H24 E. coli isolates. The data suggest the need to define serotype-specific epitopes among H7, H23, and H24 E. coli flagella. The anti-H7 MAbs described in this report have the potential to serve as high-quality diagnostic reagents, used either alone or in combination with O157-specific MAbs, to identify or detect E. coli O157:H7 in food products or in human and veterinary clinical specimens

Consequences of Antigenic Diversity of Bovine Viral Diarrhea Virus

Two main biotypes of bovine viral diarrhea virus (BVDV) have been identified based on their ability to cause changes in tissue culture cells. The cytopathic biotype multiplies in tissue culture and kills cells, while the noncytopathic biotype slowly multiplies in tissue culture and has much less ability to kill tissue culture cells. In general, cytopathic BVDV biotypes cause acute infections that often kill the bovine fetus, while noncytopathic BVDV biotypes often result in chronic infection of the fetus which, subsequently, develops in calves and adults that carry and shed noncytopathic viruses at high levels for the rest of their lives. Previous studies have indicated that cytopathic and noncytopathic viruses are antigenically similar. Also, after vaccination of cattle with modified-live or killed BVDV vaccines, antibodies are induced that neutralize a broad range of BVDV. However, very significant antigenic diversity among BVDV has been described. Also, studies indicated that some neutralizing antibodies from cattle that have recovered from BVDV react differently with several BVD isolates. In addition, monoclonal antibodies developed against specific BVDV isolates can differentiate BVDV into several groups and, when cattle which are persistently infected with noncytopathic BVDV are challenged with cytopathic BVDV, the antibodies they produce have a very narrow range of viral neutralizing activity. Thus, some antigenic diversity among BVDV, as detected by neutralization tests, is well established. However, there is little information that shows the practical consequences of this antigenic diversity relative to the disease in cattle. The primary purpose of this study was to identify cattle in U.S. Meat Animal Research Center\u27s herd that were persistently infected with BVDV and test the isolates of BVDV from the U.S. Meat Animal Research Center herd to determine if these natural field viruses could be neutralized by serum obtained from U.S. Meat Animal Research Center cows vaccinated with killed BVDV