Bovine viral diarrhea virus serum antigen capture

Details Bovine viral diarrhea virus serum antigen capture Bovine viral diarrhea virus serum antigen capture

1997-09-23

2001-01-16

Caputa, Anthony C. (Department: 1642)

Chemistry: molecular biology and microbiology

Measuring or testing process involving enzymes or...

Involving virus or bacteriophage

C435S007100, C435S007900, C435S007920, C435S007930, C435S007940

Reexamination Certificate

active

06174667

ABSTRACT:

FIELD OF THE INVENTION
The invention pertains to the field of immunoassay tests for viral infection. More particularly, the invention pertains to the development of an antigen-capture immunoassay which can use serum, plasma, milk, mucosal fluid, or urine samples to identify animals infected with the bovine viral diarrhea virus.
BACKGROUND OF THE INVENTION
Bovine viral diarrhea virus (BVDV) currently represents a major threat to the cattle industry. First described over fifty years ago, this pathogen has been found to be both highly virulent and easily spread. Considered a primary pathogen of the bovine enteric, respiratory, reproductive, and immune systems, BVDV continues to cause significant economic losses to the cattle industry worldwide. Recent outbreaks have occurred in Canada, the U.S., and throughout the world. To help combat these problems, a simpler, more cost effective method of BVDV detection, capable of yielding results in a timely fashion, is needed to better control the spread of the BVDV virus within the cattle population. Such a diagnostic tool is particularly important in light of the ineffectiveness of currently available BVDV vaccines.
Classified as a member of the genus Pestivirus and Flaviviridae family, BVDV is closely related to sheep border disease virus (BDV), and hog cholera virus (HCV), both of which are serologically related pestiviruses. Entire or partial genomic sequencing of pestivirus isolates has allowed the determination that a high degree of sequence conservation is present among the pestiviruses. More recently, antigenic variants of BVDV have been identified, and BVDV strains have been divided into two distinct genotypes, type 1 and type 2, which have been further subdivided, based upon cytopathogenicity. Molecular cloning, and Polymerase Chain Reaction (PCR) technology have determined that the general structure of BVDV consists of a capsid protein and three envelope glycoproteins. The genome of BVDV is a 12.3 kb RNA consisting of a single open reading frame (ORF). The BVD virus is itself a small, enveloped RNA virus with positive strand polarity. This positive strand aspect of the viral genome allows the RNA to be infectious, even in the absence of virion proteins.
The BVDV is spread through the herd in a fecal-oral manner, attacking the enteric, respiratory, reproductive, and immune systems. The viral load needed to provoke symptomatic infection is correlated with the type and strain of BVD virus. In addition, BVDV has the ability to infect fetuses by crossing the placenta, often resulting in a spontaneous abortion of the fetus, and a resultant decreased fertility among infected animals. Strategies for control of BVDV range from stricter management practices, in an effort to simply reduce economic loss, to elaborate testing procedures to identify infected animals that, while effective, would entail an unacceptable level of cost. Failure of field vaccinations for BVDV have increased the need for a test protocol that will help identify and eliminate infected animals in a cost-effective way.
It should also be noted that BVDV, like other infectious disease agents, is associated with a wide variety of clinical manifestations, creating a very difficult diagnostic challenge. Common manifestations of BVDV infection can include: abortion storms, infertility, irregular heat cycles, early embryonic deaths, fetal mummification, immuno-suppression, dysentery, thrombocytopenia, and cerebral hypoplasia. Moreover, serological studies have shown that a high percentage of cattle infected with BVDV, including those considered to be persistently infected (PI), remain clinically asymptomatic. Such conditions make it imperative that a reliable, inexpensive, and easy to use test be developed to assist in the detection of BVDV-infected animals in cattle herds.
The BVD virus is typically maintained in a herd due to the presence of immuno-tolerant persistently infected carrier animals. These PI cattle are exposed to the virus in utero, but can remain clinically asymptomatic throughout the course of their lives, continually shedding fecal matter, and bodily fluids, with a high concentration of virus, and thereby posing the threat of infection for other animals as long as they remain in the herd. The virus may be present in more than half of the cattle in a herd before signs of an outbreak exhibit themselves. Symptoms of the disease are usually preceded by leukopenia, and testing efforts to date have focused on identifying this effect.
Prior outbreaks have resulted in crippling economic losses to the livestock industry; for example, in Ontario in 1993, BVDV cases increased 23% in less than one year. It should also be noted that although the historical assignment of BVDV as a pestivirus was through the species it was first found to be associated with (e.g. cattle), it is now known that pestiviruses can cross species barriers. This indicates that in areas in which wild, free-ranging ruminants (moose, buffalo, etc.) are exposed to infected cattle herds, these animals are also susceptible to infection from BVDV, or can alternatively act as a reservoir of virus capable of infecting a previously “clean”herd.
Over one hundred and fifty vaccines for BVDV have been marketed to cattle farmers over the past thirty years. These vaccines have consisted of modified live BVD virus or inactivated attenuated virus and virus particles. Recent BVDV outbreaks have occurred, however, despite the availability and use of these vaccines. Current approaches to vaccination involve repeated yearly inoculation with vaccine for cattle, and additional steps are generally taken in an attempt to assure that no calves are born as PI carriers. However, for effective control of the BVD virus to be possible, it is essential to identify the PI animals and remove them from the herd. Several different test methods have been developed for the detection of BVDV, and/or the detection of BVDV infected animals. These test methods include: reverse transcription-polymerase chain reaction, enzyme-linked immunoassay (ELISA), and standard virus isolation techniques.
Both PCR and virus isolation techniques, owing to their inherent sensitivity are each capable of detecting very low levels of BVDV virus. However, these methods are also time-consuming, relatively complex, and expensive. ELISA technology, although somewhat less sensitive, is better suited as a broad-based diagnostic tool. However, until this disclosure, antigen-disclosure ELISA tests for BVDV have continued to rely on the use of white blood cell extracts from the animal to be tested. White blood cell extracts have been necessary because BVDV proteins accumulate to relatively high concentrations within the white blood cells of infected animals, and the previous ELISA methods lacked the sensitivity to detect their target BVDV proteins in blood serum. (Homer et al., 1995). The preparation of white cell extracts is itself time consuming and relatively expensive, making any ELISA test reliant upon this extraction costly in and of itself. Thus, with regard to the methods supplied by the prior art as a whole, not only are they time-consuming, as already suggested, but they often require sophisticated laboratory facilities and highly trained technicians to complete. For this reason they are economically prohibitive to use in the broad fashion that is required for today's cattle industry.
Radioimmunoprecipitation (RIP) studies of BVDV infected cattle, have indicated a strong immune response to several BVDV glycoproteins (Donis and Dubovi 1987), including gp53
E2
, gp48, and gp25. The strength of the response to these, and other, glycoproteins, has made them targets for further study of BVDV gene expression and cytopathicity. In the course of this study, Corapi et al., (1988) generated the 15.c.5 mAb. It was found that the target for this mAb was an epitope of the BVDV gp48 (alternatively known as “EO” or E
ms
in the literature). Thereafter it was suggested by Kwang et al., (1992) that this mAb could be important in the development of a competitive ELISA d

Affiliated with

Also associated with

Rating

Bovine viral diarrhea virus serum antigen capture does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Bovine viral diarrhea virus serum antigen capture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bovine viral diarrhea virus serum antigen capture will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2507531