Quantification of cytomegalovirus DNA in blood specimens from bone marrow transplant recipients by the polymerase chain reaction

Cytomegalovirus-Associated Periodontitis and Guillain-Barré Syndrome

BACKGROUND

Guillain-Barré syndrome (GBS), an autoimmune disorder of the peripheral nervous system, is characterized by rapidly ascending neural paralysis, hyporeflexia, and areflexia. The polyneuropathy of the GBS affects one to four humans per 100,000 of the population annually throughout the world (adults and children). The pathogenesis of GBS remains unclear. However, there are increasing indications that the disease is triggered by a preceding well-established febrile infection by cytomegalovirus (CMV). The present report describes active CMV within the periodontium of a 37-year-old patient affected by GBS.

METHODS

Real-time reverse transcriptase-polymerase chain reaction (real-time RT-PCR) was performed to detect CMV, Epstein-Barr virus-1 (EBV-1), herpes simplex 1 (HSV-1) and 2 (HSV-2) virus, and enteroviruses (polio-, coxsackie-, echo-, and enteroviruses 68 and 71) from periodontal sites demonstrating advanced attachment loss. Healthy sites and sites with inflamed gingival tissue were not included in the study. Anaerobic bacterial culture determined the occurrence of potential major periodontal pathogens.

RESULTS

Real-time RT-PCR and microbiologic analysis revealed the presence of a dual infection of CMV and specific bacterial plaque. CMV, Porphyromonas gingivalis, Tannerella forsythensis, and Campylobacter species were associated with periodontitis active sites, loss of attachment, and gingival bleeding. Furthermore, periodontal sites infected by active CMV had no visible radiographic crestal lamina dura.

CONCLUSIONS

The periodontium may serve as a reservoir for CMV and a source of viral replication. However, further research is needed to test whether viral replication in the periodontium precedes the GBS symptoms.

Cytomegalovirus and Epstein-Barr virus DNA transcription in endodontic symptomatic lesions

OBJECTIVES

Productive Herpesviridae infections are implicated in the etio-pathogenesis of aggressive periodontitis. However, virtually nothing is known about a possible role of herpesviruses in pulpal and periapical pathosis. This study employed a cDNA analysis to determine transcription of human cytomegalovirus (HCMV), Epstein-Barr virus (EBV) and herpes simplex virus (HSV) in 14 recalcitrant periapical lesions and in 2 periapical healthy control sites.

METHODS

Periapical samples were collected in conjunction with periapical surgery and kept frozen until virologic examination. RNA was isolated from periapical tissue by using a guanidinium isothiocyanate-acid phenol procedure (TRIZOL LS Reagent, GIBCO BRL, Rockville, MD). cDNAs were amplified by means of oligonucleotides targeting highly conserved regions of the test viruses and the RT-PCR-100 amplification kit (Sigma-Aldrich, St Louis, MO). Standardization of PCR primer sensitivity and validation was carried out according to established methods. Amplification products were identified by agarose gel electrophoresis.

RESULTS

HCMV transcript was detected in 12 of 13 symptomatic and in 1 asymptomatic periapical lesion. EBV transcript was demonstrated in 8 of the 13 symptomatic lesions but not in the asymptomatic periapical lesion. HCMV and EBV dual transcription occurred at higher frequency in periapical lesions showing radiographic bone destruction of 5 mm x 7 mm or larger than in smaller size lesions (P = 0.03; Chi-squared test). No HCMV or EBV transcription was identified in the 2 healthy control sites. HSV transcript was not detected in any study site.

CONCLUSION

The present data suggest that HCMV or EBV infections participate in the pathogenesis of periapical symptomatic lesions. Herpesviruses may produce periapical pathosis as a direct result of viral infection and replication, or as a consequence of virally induced impairment of the host defense and subsequent increased virulence of resident bacterial pathogens.

Persistent parvovirus B19 infections with different clinical outcomes in renal transplant recipients: diagnostic relevance of polymerase chain reaction (PCR) and of quantification of B19 DNA in sera

OBJECTIVE: To study parvovirus B19 infection in immunocompromised subjects such as renal transplantation recipients. METHODS: Two cases of B19 infection in renal transplant recipients have been included in the study. The outcome of the infection has been studied by both serologic and virologic methods. A monitoring of the DNAemia was done by a nested PCR in endpoint titration assays. RESULTS: In one patient with severe anemia an acute B19 infection was diagnosed by PCR 26 days after the transplant; a high level of DNAemia persisted until an intravenous immunoglobulin treatment. Then a sharp decrease of the DNAemia was shown, without full clearance of B19 virus. In a lymphocyte suspension from the organ donor, B19 DNA was detected. In the other patient, who recovered spontaneously from anemia, a persistent B19 infection was demonstrated at day 106 after transplantation and was still demonstrable after 470 days. CONCLUSIONS: A high level of B19 DNAemia was associated with symptomatic infection, with severe anemia, whereas low-level DNAemia was long-lasting in asymptomatic subjects with impaired immunologic responses. The endpoint titration assay by nested PCR was very useful for the monitoring of B19 infection, particularly following the therapeutic intravenous immunoglobulin administration.

Herpesvirus DNA is frequently detected in liver tissue from hepatitis C patients

BACKGROUND AND AIMS

Herpesviruses infect the liver and cause minor hepatitis. Our aim is to verify the presence of herpesviruses in the liver from hepatitis C patients and the possible influence of these viruses in the liver disease.

METHODS

We searched for herpesvirus DNA in liver biopsies from patients with hepatitis C and from a control group without hepatitis by means of nested polymerase chain reaction. Serological investigations were carried out as well.

RESULTS

Thirty-four liver specimens from hepatitis C patients were examined, 12 of which (35.3%) were positive for at least one herpesvirus DNA, whereas among the 19 control specimens only two were positive (10.5%; P = 0.049). Liver biopsies from seven patients, three with acute hepatitis of unknown origin, three with non-alcoholic steatohepatitis and one with autoimmune hepatitis were also investigated and three positive samples were found.

CONCLUSIONS

The prevalence of herpesvirus DNA was found higher in patients with hepatitis C than in individuals without hepatitis. The influence of herpesviruses on the clinical course of hepatitis C is considered.

Simplified PCR set-up using a frozen preformulated mix for the detection of cytomegalovirus

A simple PCR set-up for the detection of cytomegalovirus in clinical specimen was developed. All components of the PCR master mix including Taq DNA polymerase, uracil N-glycosilase, and primers were preformulated and stored frozen in aliquots. After thawing the master mix aliquots, the PCR was immediately started after the addition of sample DNA. This method gave excellent reproducible PCR-results without loss of enzyme activities following storage at -20 degrees C for at least 4 months.

Determination of cytomegalovirus DNA load for monitoring of cytomegalovirus disease and antiviral treatment in solid organ transplant patients, comparing limiting-dilution PCR and hybrid capture assay with cytomegalovirus isolation

OBJECTIVE: To improve the identification of patients at risk of developing cytomegalovirus (CMV) disease. MATERIALS AND METHODS: In a prospective study of 50 kidney or liver transplant patients who developed fever, 133 EDTA blood samples were analyzed, using two tests to measure CMV DNA: a 10-fold limiting dilution of an extract of 2 million leukocytes for CMV PCR, and a CMV hybrid capture assay. Both tests were compared with virus isolation, using an equivalent amount of leukocytes as a base for all three tests. RESULTS: The limiting-dilution CMV PCR and the hybrid capture assay presented relatively similar changes of sensitivity and specificity at different CMV DNA concentrations. The kinetics of the positive and negative predictive values were also comparable. A higher CMV DNA load corresponded to an increased risk of developing CMV disease. Furthermore, an increase in the endpoint dilution of a positive CMV PCR also corresponded to more severe disease. After antiviral treatment, the CMV PCR decreased by at least 100-fold (2 log10) in 10 cases and by 10-fold (1 log10) in five cases. Thus, there was a decrease in 15 of 18 (83%) patients. Similarly, with the hybrid capture assay, the amount of CMV DNA decreased about 100-fold in five patients and decreased by about 0.5 genome equivalents in five cases, i.e. in 10 of 12 (83%) patients. CONCLUSION: Both methods proved clinically useful for detecting patients at risk of developing CMV disease and for monitoring antiviral treatment in solid organ transplant patients.

Qualitative and semiquantitative polymerase chain reaction testing for cytomegalovirus DNA in serum allows prediction of CMV related disease in liver transplant recipients

AIM

To identify cytomegalovirus (CMV) infection in liver transplant recipients by polymerase chain reaction (PCR) techniques and to separate the cases in which CMV related disease will occur, for whom treatment is indicated, from those in whom infection will remain innocuous.

METHODS

The combination of qualitative and semiquantitative PCR of serum and urine was assessed to determine whether these assays can identify those at risk of CMV related disease and compared their performance with conventional approaches to diagnosis.

RESULTS

Qualitative PCR of serum had superior specificity, sensitivity, and positive and negative predictive values compared with urine DEAFF (detection of early antigen fluorescent foci) and PCR of urine. All episodes of CMV related disease were associated with the presence of CMV DNA by PCR in serum or urine; CMV was detected before clinical onset in 70% and 60% of cases, respectively. The period over which CMV DNA could be detected was not correlated with CMV related disease. Both peak viral load and cumulative viral load estimated using a semiquantitative PCR method on serum samples positive by the qualitative method could be used to distinguish asymptomatic infection from CMV related disease with 100% specificity and sensitivity. In contrast semiquantitative PCR of urine was of little value.

CONCLUSIONS

An approach based on PCR testing with a combination of qualitative and subsequently semiquantitative serum samples would improve the diagnosis of CMV infection and aid identification of those patients at risk of CMV related disease, allowing treatment to be targeted specifically.

Encephalomyeloradiculopathy associated with Epstein-Barr virus: primary infection or reactivation?

INTRODUCTION

Encephalomyeloradiculopathy (EMR) is a new syndrome, characterized by extensive involvement of the nervous system at different levels, including brain, medulla and spinal roots. We describe a patient presenting with prodromal febrile illness, followed by a wide infection of the nervous system with transverse myelitis and less severe meningitis, encephalitis and polyradiculopathy. The patient was treated with high-dose corticosteroids, antibiotics and acyclovir; in spite of therapy his condition improved very slowly, with severe neurological sequelae.

MATERIAL AND METHODS

Antiviral antibodies were searched for in serum and cerebrospinal fluid (CSF) by commercially available ELISA kits. Viral investigations were performed by cell culture isolation and search for viral antigens, and genomic nucleic acids were investigated by polymerase chain reaction (PCR).

RESULTS

Virological and serological studies evidenced a primary infection by cytomegalovirus (CMV), possibly responsible for the prodromal illness, persisting in the course of the disease. PCR performed in the peripheral blood mononuclear cells (PBMCs), DNA collected early and in the CSF drawn 30 days after the onset of the disease showed Epstein-Barr virus (EBV) DNA. The serum panel of EBV antibodies was typical of an intercurrent virus reactivation, more than of a primary infection.

CONCLUSION

EBV is known to be highly infectious for the nervous system, in this case of EMR the presence of DNA sequences in the PBMCs and CSF suggests that EBV plays a role in the development of this newly described syndrome.

Monitoring for cytomegalovirus infection in organ transplant recipients: analysis of pp65 antigen, DNA and late mRNA in peripheral blood leukocytes

The use of sensitive and specific methods for rapid and reliable diagnosis is required due to the considerable impact of human cytomegalovirus (HCMV) in organ transplant recipients. For this purpose the demonstration of the presence of viral antigens in peripheral blood leukocytes (PMNLs) and of viral nucleic acids in the same cells or in sera would seem to be of valid support. The present study was designed to test pp65 antigen, HCMV DNA and HCMV late mRNA in order to provide clinical information for the management of the infection. Fifty solid organ recipients were monitored for six months after transplant. The data obtained from the various tests were analysed from the first evidence of HCMV infection revealed by positive antigenaemia and/or DNA-polymerase chain reaction (PCR). In 3 asymptomatic and in 7 symptomatic patients, PCR became positive 1-2 weeks before antigenaemia but PCR did not discriminate the clinical evolution of HCMV infection. The antigenaemia test well correlated to the development of viral infection being positive in all symptomatics and in 31, 2% of asymptomatics. The antigenic load > 100/2 x 10(5) positive cells was always associated with clinical signs of illness. The detection of late mRNA was more indicative of the virus replicative status in the follow-up of patients treated with ganciclovir. In some cases there was evidence, prior to the other two tests, the block of viral replication due to the antiviral therapy and in others the onset of HCMV infection relapse.

Relevance of clinical and laboratory findings in the diagnosis of cytomegalovirus encephalitis in patients with AIDS

A retrospective evaluation was conducted in patients with AIDS and an autopsy diagnosis of cytomegalovirus (CMV) encephalitis to determine the relevance of clinical and laboratory findings in establishing a diagnosis. On autopsy of 100 patients, CMV encephalitis was diagnosed in 13 patients; eight had periventricular CMV encephalitis, four micronodular CMV encephalitis, and one both conditions. Seven patients had had a CMV infection previously (6 cases of retinitis, 1 case of colitis), and at the onset of encephalitis all of them were receiving a maintenance dose of ganciclovir. Examination of the CSF showed specific changes in patients with periventricular encephalitis. CT revealed no characteristic findings, while MRI showed an increased signal intensity on T2 weighted images. CMV DNA amplification by nested PCR was performed in nine patients with CMV encephalitis; PCR was positive in eight patients whose CSF was collected during CMV encephalitis, and negative in one patient whose CSF was collected six months before death. In conclusion, some clinical findings suggest a presumptive diagnosis, especially of periventricular encephalitis, and nested PCR appears to be a reliable and rapid technique for making an antemortem diagnosis.

Comparison of three luminescent assays combined with a sandwich hybridization for the measurement of PCR-amplified human cytomegalovirus DNA

Identification of human tissue contaminated by cytomegalovirus is currently carried out by PCR amplification followed by measurement of the amplicons. Three luminescent detection systems undertaken after sandwich hybridization of the amplicons were compared. The sandwich hybridization takes place between a covalent linked capture probe, bound onto a plastic 96-well plate, and a biotinylated or digoxigenin-labeled detection probe. The three non-isotopic luminescent detection systems need either streptavidin-conjugated peroxydase or streptavidin-conjugated pyruvate kinase or antibodies conjugated with alkaline phosphatase. Detection of the enzymes was carried out by measurement of light emission in the presence of, respectively, luminol for peroxidase or dioxethane for alkaline phosphatase. The kinase assay was carried out not only in the presence of its substrates, ADP and phospho-enol pyruvate, but also of luciferase, which converts the produced ATP into light. The method was found to be sensitive, with the luciferase bioluminescent assay with the production of a long lasting signal. Amplicons from eight clinical samples were detected by this combination of sandwich hybridization and the three luminescent assays. The results were comparable with nested PCR for the identification of positive samples. The same correlation was obtained with 45 clinical samples using only the pyruvate kinase detection system. The high performance of these assays is given by the specificity of the sandwich hybridization combined with the sensitivity of the luminescent detection systems.

Usefulness of DNA viral load quantification for cytomegalovirus disease monitoring in renal and pancreas/renal transplant recipients

BACKGROUND

The purpose of this prospective study was to evaluate the usefulness of quantifying DNA-cytomegalovirus (CMV) load for the diagnosis and monitoring of CMV disease among renal and pancreas transplant patients under immunosuppressive drugs.

METHODS

A longitudinal study was conducted among 34 consecutive, unselected renal and pancreas/renal transplanted patients in our unit. During the first 3 posttransplant months, weekly monitoring of CMV infection and CMV disease was done, involving the determination of viremia by the shell vial assay, qualitative DNAemia by semi-nested polymerase chain reaction (PCR) and quantitative DNAemia by the hybrid capture system (HCS), a new and original hybridization method (337 samples were collected for each test). Qualitative and quantitative DNAemia results were blinded to physicians and three grades of disease were defined according to CMV related symptom occurrence.

RESULTS

PCR was the most sensitive (100%) but the least specific (78%) method for the diagnosis of CMV disease. HCS was specific for CMV genome detection, sensitive and reproducible. Blood DNA levels above 60 pg/ml were predictive of severe or moderate CMV disease (sensitivity, 92%; specificity, 100%). A significant decrease in viral load was observed after ganciclovir administration, and a positive PCR or HCS result at the end of the antiviral treatment was associated with relapse of CMV infection or disease.

CONCLUSIONS

It is concluded that quantitative DNAemia detection, with this new commercially available method, can predict disease and may be useful for a rational evaluation of ganciclovir preemptive therapy in such patients.

Successful quantification of cytomegalovirus DNA by competitive PCR and detection with capillary electrophoresis

Human cytomegalovirus (HCMV) is responsible for severe infections in immunocompromised patients. Viral load has recently been identified as one of the major risk factors for subsequent development of HCMV disease. In this context, we developed a protocol allowing rapid, sensitive and precise quantification of HCMV DNA using competitive PCR run to saturation. Long primers were used for amplification, and internal DNA standard was constructed by PCR, with a primer inducing formation of a loop on the target sequence. The obtained fragment differed from the wild one (142 bp) by 6 bp. Quantitative analysis of PCR-amplified HCMV DNA was carried out using an original system combining capillary gel electrophoresis and u.v. detection. This procedure was evaluated on renal transplant recipients, and the results of quantitative PCR were compared with those of viraemia, qualitative DNAemia and HCMV-related symptoms. High levels of HCMV DNA were associated with HCMV-related symptoms, and in all cases a significant decrease of viral load was observed following DHPG treatment. Competitive PCR with capillary electrophoresis detection appears to provide a sensitive quantification method for HCMV DNA in leukocytes and is easily adaptable to routine laboratory use.

The role of PCR in the diagnosis and management of CMV in solid organ recipients: what is the predictive value for the development of disease and should PCR be used to guide antiviral therapy?

Cytomegalovirus remains a significant source of morbidity and mortality in immunocompromised hosts. The increased sensitivity of molecular diagnostic techniques (PCR, antigenemia) has resulted in our ability to detect viral replication earlier in the posttransplant period, before the onset of symptoms. With the advent of effective antiviral therapy, "preemptive therapy," guided by sensitive, early and specific predictors of CMV disease, has become a realistic objective. Although multiple studies have analyzed the sensitivity and specificity of these tests, their predictive value for the development of disease has not been defined. The purpose of this study was to evaluate the predictive value of a positive CMV PCR in the setting of solid abdominal organ transplantation. A total of 476 PCR assays were performed on 134 transplant recipients (102 kidney, 19 kidney/pancreas, 11 liver, 2 other) either as protocol serial samples or as dictated by clinical events. All samples were concomitantly analyzed using standard virological assays for CMV including culture, shell vial, and serology. Patients with any CMV seropositive donor/recipient (D/R) combination received ganciclovir prophylaxis in conjunction with antilymphocyte induction for 14 days. No subsequent CMV prophylaxis was used. The positive predictive value was 55% in all seropositive donor/recipient combinations. The highest risk group (seronegative recipient of seropositive donor) showed the highest positive predictive value, whereas seropositive recipients of either seropositive or seronegative donors showed positive predictive values of 45% and 25%, respectively. Negative predictive value was 100% for all groups. Early detection of CMV infection has important implications for patient management, including preemptive therapy, which can be guided by PCR, especially in high risk (D+/R-) patients.

Human cytomegalovirus and acute rejection after heart transplantation are not directly associated

Retrospective and prospective analyses of heart transplant recipients showed no significant association between acute rejection and the detection of cytomegalovirus (CMV) infection by culture or the polymerase chain reaction (PCR) for viral DNA, neither on grounds of the incidence of both conditions nor in relation to which was diagnosed first in the patient. Semiquantitative PCR of serial blood and endomyocardial biopsy specimens from individual patients revealed different patterns in the development of the viral DNA in the blood and the heart, also clear episodes of CMV infection in CMV antibody-negative recipients of hearts from CMV antibody-negative donors, none of whom went on to develop a CMV-specific antibody response. None of these findings was associated with the development of rejection in the patient. On the other hand, in those patients who did experience rejection, peak levels of CMV DNA in the blood and the heart were usually not reached until 6 weeks or more after transplantation, whereas in those in whom rejection was not detected at all during the period of observation, peak levels of CMV DNA were detected earlier, mainly within the first 6 weeks after transplantation. In several cases, the delayed increase in CMV DNA in those with rejection, albeit not the delay itself, was linked to treatment with steroids. These findings support the view that CMV infection and rejection are independent events, but that the timing of the infection, and whether or not rejection is detected, are indicative of the general status of the immune response in individual patients.

Rapid, non-radioactive detection of virus infection by polymerase chain reaction

BACKGROUND

Polymerase chain reaction (PCR) diagnosis of infectious diseases, especially virus diseases, offers a very sensitive and specific technique for clinical diagnosis. However, detection systems for amplified DNA requiring radioactive probe hybridization or signal development using blot transfer or nucleotide capture require overnight incubation or specially labeled probe molecules for analysis of amplified DNA.

OBJECTIVES

To place this technology in the clinical laboratory, rapid and sensitive methods are needed for the detection of amplified DNA which are applicable to the assay of multiple specimens representing many different organisms and requiring a minimum of manipulation.

STUDY DESIGN

Electrophoretic separation of amplified DNA fragments, stained with the fluorescent dye SYBR Green I, and laser scanning of the gels for detection of virus-specific PCR products was compared with detection of amplified DNA by liquid hybridization with radioactive probes and gel retardation analysis of labeled probe molecules.

RESULTS

Fluorescent scanning methodology was applied to the detection of cytomegalovirus (CMV), herpes simplex virus (HSV) and the human immunodeficiency virus (HIV). This method was at least 10 times more sensitive than radioactive probe hybridization in the detection of CMV-specific PCR products. This method also required less time and avoided the use of radioactivity.

CONCLUSIONS

Clinical diagnosis of virus infections can be conveniently and rapidly accomplished, while avoiding the dangers of radioactive probe handling, by fluorescence staining and laser scanning of specifically amplified gene fragments. This technology is applicable to the detection of genes from many different organisms, without specially synthesized and/or labeled oligonucleotide primer or probe sequences.

Search for human herpesvirus 6 and human cytomegalovirus in bronchoalveolar lavage from patients with human immunodeficiency virus-1 and respiratory disorders

Virus isolation and viral DNA detection by the polymerase chain reaction were used to investigate the presence of human herpesvirus 6 (HHV-6) and human cytomegalovirus (HCMV) in bronchoalveolar lavage from 34 human immunodeficiency virus-1 (HIV-1)-infected patients with respiratory disorders. The aim was to assess the presence of reactivated HHV-6 in lung tissues for a subsequent evaluation of the frequency of virus involvement in respiratory clinical manifestations in the course of HIV-1 infection. Bronchoalveolar lavage samples were tested for the presence of HCMV, as a routine investigation within a protocol monitoring opportunistic infections in symptomatic HIV-1 patients. Whereas HCMV DNA was detected by the polymerase chain reaction in 12 bronchoalveolar lavage specimens, 10 of which were also positive for virus isolation, all samples were negative for HHV-6 by both virological procedures. The HHV-6 DNA finding in bronchoalveolar lavage from an HIV-1-seronegative patient with renal carcinoma, investigated accidentally together with the bronchoalveolar lavage specimens from HIV-1 seropositive patients, stressed the HHV-6 polymerase chain reaction-negative results in the bronchoalveolar lavage samples under study. It is concluded that the lung may be a target organ for HCMV infection in HIV-1-seropositive patients affected by respiratory symptoms but that this does not seem to be the case for HHV-6.

A polymerase chain reaction to detect a spliced late transcript of human cytomegalovirus in the blood of bone marrow transplant recipients

A reverse transcription (RT) nested polymerase chain reaction (PCR) procedure is described for detecting RNA to a spliced late gene (SLG) of human cytomegalovirus (CMV), the product of which (175 bp) is easily differentiated in agarose gels from the product when the target is unspliced viral RNA or DNA (258 bp). The SLG-RT-PCR has been compared against a semi-quantitative PCR for CMV DNA in buffy-coat specimens collected weekly after bone marrow transplantation from 3 patients and against the results of culturing these specimens for CMV both by conventional virus isolation, based on the detection of cytopathic effect, and by the early detection of infected cells by staining with virus-specific monoclonal antibodies. The detection of CMV RNA by SLG-RT-PCR correlated well with the detection of infective virus but only when the results of both culture methods were combined, in that neither culture method alone was as sensitive as the SLG-RT-PCR. The presence of SLG RNA in the circulation is of value as a marker of active CMV infection.

Quantitative PCR. A survey of the present technology

PCR-based amplification of nucleic acids has had a major impact in almost every field of basic research and has already found extensive applications in the area of clinical diagnosis. For many of these applications, quantitative data are sought to relate the quantity of amplified product to the amount of original target nucleic acid present in the sample. Since the PCR methodology with its exponential nature can be adapted for this purpose, a lot of different strategies have emerged in the last few years for sensitive and specific PCR product detection and quantification. Basic strategies, including the use of external and internal standards, are presented with respect to statistical aspects, and the advantages as well as the limitations of individual protocols are discussed. Furthermore the suitability of conventional laboratory techniques, such as gel systems or HPLC, nonradioactive labeling procedures, and the principles of advanced solid-phase-mediated strategies for the precise determination of amplification products, are outlined with the help of selected examples.