Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving virus or bacteriophage
Patent
1994-01-12
1996-09-03
Elliott, George C.
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving virus or bacteriophage
435 6, 435 912, 435 9151, C12Q 170, C12Q 168, C12P 1934
Patent
active
055522696
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the diagnosis in man and animals of diseases due to retrovirus and, in particular, the diagnosis of infection by the human immunodeficiency virus (HIV).
Retroviruses are part of the Retroviridae family and are RNA viruses which, due to their reverse or inverse transcription (hereinafter abbreviated "RT"), can transcribe their RNA genome into DNA. A retrovirus is thus able to be introduced into the cells which act as its host, in the form of chromosomal or extrachromosomal DNA. As a result, a retrovirus exists in two forms:
In free form, as mobile RNA genetic element, capable of passing from one cell to another;
In cell form retrotranscribed in DNA, which constitutes the form necessary for its multiplication.
In accordance with the present classification, the Retroviridae family is divided into three subfamilies: Onconvirinae, Spumavirinae and Lentivirinae.
For greater clarity, explanations which follow and the practical details of the invention which will be set forth further below are given with reference to the HIV retrovirus, which is part of the Lentivirinae family.
However, what is stated or shown with regard to this virus applies, mutatis mutandis, to other retroviruses. It is therefore understood that the present patent application is not limited to the human immunodeficiency retrovirus and that it is simply in a desire to simplify the description and/or the methodological indications that reference is primarily had thereto.
The importance of the diagnosis of infections by retrovirus and the problems relating thereto are summarized below:
Almost all persons who are seropositive for the human immunodeficiency virus (HIV) develop AIDS within a period of 3 to 15 years after infection.
The development of AIDS has, up to now, been fatal in all cases.
The present goals of the person skilled in the art is concerned with the developing of remedies or vaccines, methods of treatment, and/or methods of diagnosis are: determination of whether what one is confronted with in this patient is a rapid development towards AIDS or, on the contrary, of a lengthy stability of the infection; and seropositive patient. Up to the present time, this evaluation has required a very large number of patients and a long period of surveillance, due to the fact that the evaluation criteria adopted for a treatment are the triggering of AIDS or death, which events occur after years of development in a seropositive patient.
Research work during the last few years has led, in order to satisfy these two goals, to trying to evaluate the amount of virus itself present in the organism, either in the form of retrotranscribed virus in the form of DNA in the circulating cells of the blood and particularly in the T4 cells, or in the form of free virus in the serum of the patients (in the form of RNA).
At present, two techniques are known for measuring viral concentration.
A coculture technique makes it possible to measure, in vitro, the percentage of infected cells in the blood. This percentage is low (less than 1/30,000) in seropositive persons who will remain stable and asymptomatic for the following two or three years, but, on the other hand, high (greater than 1/3,000) in seropositive persons who are going to evolve rapidly towards AIDS. The study of these percentages also makes it possible to follow up the effectiveness of a drug.
However, this culture technique has drawbacks. In particular, it requires a laboratory qualified for active viral cultures, known as the P3 type. Furthermore, the operations corresponding to the culture can last up to 30 days, which is obviously too long for an important laboratory examination, which could possibly be used as routine in numerous patients.
A second type of technique is measurement of the viral DNA of the cells. The measurement of this DNA is effected by a process of physical-chemical amplification employing the well-known technique today of the polymerase chain reaction (commonly known by the abbreviation "PCR"). [See, for example, "Recent Advances in the Polymera
REFERENCES:
Kawasaki, Amplifications--A Forum for PCR Users, Sep. 1989, pp. 4-6.
Eron et al., 1992, Proc. Natl. Acad. Sci. U.S.A. 89:3241-3245.
Lu and Andrieu, 1992, J. Virology 66:334-340.
Bourinbaiar, 1991, Nature 349:111.
Genesca et al., 1990, J. Infectious Diseases 162:1025-1030.
Andrieu Jean-Marie
Lu Wei
Aremas (Association pour la Recherche, l'Etude, le Traitment et
Elliott George C.
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