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Patent Issued for Oral Fluid Rapid Assay for Hepatitis C Virus (HCV) Antibodies Using Non-Antibody Labeling of IgA Molecules Recognizing HCV Peptide...

July 16, 2014

Patent Issued for Oral Fluid Rapid Assay for Hepatitis C Virus (HCV) Antibodies Using Non-Antibody Labeling of IgA Molecules Recognizing HCV Peptide Epitopes

By a News Reporter-Staff News Editor at Vaccine Weekly -- According to news reporting originating from Alexandria, Virginia, by NewsRx journalists, a patent by the inventors Zmuda, Jonathan (Germantown, MD); Liotta, Lance A. (Bethesda, MD); Whiteley, Gordon (Potomac, MD), filed on February 14, 2012, was published online on July 1, 2014 (see also Instant Medical Diagnostics, LLC).

The assignee for this patent, patent number 8765386, is Instant Medical Diagnostics, LLC (Potomac, MD).

Reporters obtained the following quote from the background information supplied by the inventors: "Hepatitis C(HCV) is the major cause of parenterally transmitted non-A, non-B hepatitis (Choo et al., 1989 Science 244:359-362; Kuo et al., 1989, Science 244:362-364) with a prevalence of 1-3% throughout the world (Davis et al., 1998, Hepatology 28(Suppl 4, pt 2):99A). Chronic disease develops in 60-85% of patients, with cirrhosis representing a major hallmark of HCV infection. Among patients whose infection progresses to cirrhosis, as many as 1-4% develop hepatocellular carcinomas annually (Fattovich et al., 1997, Gastroenterology 112:463-472). It is estimated that the need for hepatic transplantation for infected individuals will increase 5-7 fold in the next 20 years unless more effective treatments and preventative programs are introduced (Davis et al., 1998, Hepatology 28 (Suppl 4, pt 2):99A).

"While additional anti-viral therapies are needed to combat the spread of HCV, equally necessary is the development of a rapid, highly sensitive and cost-effective test to detect and monitor HCV within the population. Current PCR and ELISA-based assays for the detection of HCV are costly, relatively slow and reliant upon serum or plasma as the sample fluid. The substitution of oral fluid for serum in HCV assays would provide a cost-effective, non-invasive means to conduct routine screening and would facilitate sample procurement from patient groups where serum collection is difficult, such as intravenous drug users, who constitute a significant portion of total HCV cases.

"A number of oral fluid-based assays have been designed for the detection of viral antibodies with good results. Virus-specific antibodies have been detected in the oral fluid of patients infected with human immunodeficiency virus (Major et al., 1991, J. Infect. Dis. 163:699-702), hepatitis A (Stuart et al., 1992, Epdiem. Infect. 109:161-166), hepatitis B (Ben Aryeh et al., 1985, Arch. Oral Biol. 30:97-99), rubella (Saleh, 1991, J. Egypt Public Health Assoc. 66:123-124) and following immunization against polio (Zaman et al., 1991, Acta Paediatrica Scan. 80: 1166-1173), rotavirus (Ward et al., 1992, J. Med. Virol. 36: 222-225) and hepatitis A (Laufer et al., 1995, Clin. Infect. Dis. 20:868-871). For HCV, ELISA-based assays developed initially for use with serum or plasma have been modified to detect anti-HCV antibodies in oral fluid (Cameron et al., 1999, J. Viral Hepatitis 6:141-144; Elsana et al., 1998, J. Med. Virol 55:24-27; McIntyre et al., 1996, Eur. J. Clin. Microbiol. Infect. Dis. 15:882-884; Sherman et al., 1994, Amer. J. Gastroent 89:2025-2027; Thieme et al., 1992, J. Clin. Microbiol. 30:1076-1079); using a modified protocol with the HCV 3.0 ELISA (Ortho Diagnostic Systems), (McIntyre et al. 1996, Eur. J. Clin. Microbiol. Infect. Dis. 15:882-884) detected anti-HCV antibodies within a group of 18 HCV(+) and 49 HCV(-) oral fluid samples with 72% sensitivity and 98% specificity. In the same study, 100% sensitivity and 100% specificity was achieved using the Monolisa HCV assay (Sanofi Pasteur Diagnostics, France). It is unclear what the differences were that lead to the increased sensitivity of the Monolisa test, and thus care must be taken in the interpretation of results obtained from tests not designed specifically for use with oral fluid. None of these assays has achieved the sensitivity required for a rapid point of care test. None of these assays has disclosed the special role of oral fluid IgA in human oral fluid as a key determinant of sensitivity and specificity for HCV screening.

"An intrinsic difficulty in designing oral fluid-based diagnostic assays, however, is detecting a sufficient proportion of the relatively low levels of antibody present in oral fluid to generate a meaningful diagnostic result. Indeed, it is estimated that overall antibody levels are 800-1000-fold lower in oral fluid than in serum (Parry et al., 1987, Lancet 2:72-75) making detection sensitivity of the utmost importance in oral fluid-based tests. While this problem is significant, an HCV assay designed to be used specifically with oral fluid as the diagnostic fluid, and not simply a serum-based assay modified for use with saliva, could overcome this complication and provide an important test for HCV in the population."

In addition to obtaining background information on this patent, NewsRx editors also obtained the inventors' summary information for this patent: "The invention disclosed is a means to detect antibodies against HCV using oral fluid as a sample medium. Assays in the prior art have not achieved the sensitivity and specificity required to rapidly screen HCV infection in human oral fluid. Most critically, the use of a labeled detection molecule that recognizes not only IgG, but all classes of immunoglobulins, enhances the ability to detect anti-HCV in oral fluid in an ELISA format or using a flow-through system. When detecting anti-HCV using a labeled detection molecule that recognizes only anti-HCV of the IgG class, detection sensitivity was vastly reduced. The incorporation of a detection method that labels multiple classes of anti-HCV, on the other hand, allows for increased detection sensitivity of samples that would otherwise be scored negative using a detection method that only recognizes IgG.

"By coupling this detection method to an assay that utilizes a membrane with immobilized HCV peptide antigens present as a trapping zone, followed by subsequent flow of sample through the trapping zones and selective binding of labeled antibodies specific for HCV epitopes within the trapping zone, an immunoassay for the detection of anti-HCV can be performed in a short time period (

"The use of an assay to detect anti-HCV in saliva would also be of benefit in the rapid and non-invasive detection of antibodies following vaccinations and monitoring of vaccination efficacy over time, monitoring therapeutic response of patients to treatment regimes and screening for early infection, as IgA antibodies are known to be an important part of the early stages of the immune response.

"Thus, the present invention seeks to overcome the deficiencies of the prior technology by designing an HCV assay that would meet the following objectives. A first objective is that the test is non-invasive, generates minimal risk of infection to those administering the test and can be performed from start to finish by non-medical personnel.

"A second objective is that the test is rapid (

"A third objective is that the test is specialized to detect the specific class of anti-HCV antibodies in oral fluid, and is not simply a modification of a current serum-based assay.

"A fourth objective is that the test incorporates a number of different HCV antigens to minimize false negative results.

"A fifth objective is that the test is adaptable to future incarnations of the assay to meet specific diagnostic needs, and that it is sensitive enough to detect extremely low levels of anti-HCV."

For more information, see this patent: Zmuda, Jonathan; Liotta, Lance A.; Whiteley, Gordon. Oral Fluid Rapid Assay for Hepatitis C Virus (HCV) Antibodies Using Non-Antibody Labeling of IgA Molecules Recognizing HCV Peptide Epitopes. U.S. Patent Number 8765386, filed February 14, 2012, and published online on July 1, 2014. Patent URL:

Keywords for this news article include: Antibodies, Virus, Immunology, Blood Proteins, Viral Vaccines, Immunoglobulins, Instant Medical Diagnostics LLC.

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Source: Vaccine Weekly

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