Early diagnosis and monitoring of human cytomegalovirus pneumonia in patients with adult T-cell leukemia by DNA amplification in serum

Peripheral blood leukocytes and serum nested polymerase chain reaction are complementary methods for monitoring active cytomegalovirus infection in transplant patients

BACKGROUND

Human cytomegalovirus is an important cause of morbidity and mortality in immunocompromised patients. Qualitative polymerase chain reaction (PCR) has proven to be a sensitive and effective technique in defining active cytomegalovirus infection, in addition to having low cost and being a useful test for situations in which there is no need for quantification. Real-time PCR has the advantage of quantification; however, the high cost of this methodology makes it impractical for routine use.

OBJECTIVE

To apply a nested PCR assay to serum (sPCR) and to evaluate its efficiency to diagnose active cytomegalovirus infection compared with PCR of peripheral blood leukocytes (L-PCR).

METHODS

Samples of 37 patients were prospectively evaluated. An internal control was created and applied to sPCR to exclude false-negative results.

RESULTS

In total, 21 patients (57%) developed active cytomegalovirus infection. After analyzing the two methods for the diagnosis of active infection, higher sensitivity and negative predictive value of the L-PCR versus sPCR (100% versus 62%), and higher specificity and positive predictive value of sPCR versus L-PCR (81% versus 50% and 72%, respectively) were observed. Discordant results were observed in 11 patients who were L-PCR-positive but sPCR-negative for active cytomegalovirus infection, five of whom developed clinical symptoms of cytomegalovirus. Clinical symptoms were observed in 14 patients, 12 of whom were diagnosed with active infection by nested L-PCR (P=0.007) and seven by nested sPCR (P=0.02). Higher specificity and a positive predictive value for sPCR were observed.

CONCLUSION

Nested L-PCR and sPCR were considered to be complementary methods for the diagnosis and management of symptomatic cytomegalovirus infection.

Application of nested PCR for diagnosis of histoplasmosis

Histoplasmosis is a fungal infection that, although not endemic in Japan, has seen a rise in the number of Japanese cases since the mid-1980s. Diagnosis of the disease is not straightforward, and the main method of detection, fungal culture (which has biosafety-related issues), is of low sensitivity in general. Alternative methods that depend on antibody or antigen detection have had limited use. We have developed a histoplasmosis detection method based on PCR amplification of the Histoplasma capsulatum M antigen gene. We compared this method with fungal culture and serological diagnostic techniques. Among five cases that were finally diagnosed as histoplasmosis, the fungal culture method was only successful in identifying one such case. Although the presence of anti-H. capsulatum antibodies was confirmed in three cases, our PCR method identified four of five cases of histoplasmosis. The performance of our PCR method could not be compared with the antigen detection method, which is used in the United States but is not routinely used in Japan. However, the PCR method was shown to have high sensitivity and specificity for H. capsulatum. Although the number of histoplasmosis cases examined in this study was small, our data suggest that the molecular diagnosis technique has potential for increasing the reliability of histoplasmosis diagnosis when used in combination with established methods.

An outbreak of histoplasmosis among healthy young Japanese women after traveling to Southeast Asia

Histoplasmosis, caused by Histoplasma capsulatum, is an endemic mycosis in many countries of the world except for Japan. Outbreaks of histoplasmosis among Japanese people are very rare and are mainly imported by travelers. We report an outbreak of histoplasmosis among healthy Japanese people who traveled to a resort area in Southeast Asia. Three young Japanese women traveled to Langkawi island, Malaysia and stayed on the island for five days without visiting caves, a known reservoir of H. capsulatum. All three individuals developed flu-like symptoms with multiple nodule shadows on chest X rays or chest CT scans at around ten days after their return to Japan. Serum samples obtained from the three subjects were positive for anti-Histoplasma antibody and specific PCR for H. capsulatum on lung biopsy specimens and the serum from one patient was positive. The clinical course of all three patients improved without the use of anti-fungal agents and no recurrence has been confirmed. Clinical attendants should consider histoplasmosis when they see patients with flu-like symptoms with abnormal chest X-rays after visiting H. capsulatum endemic areas, especially Southeast Asia.

EBV and CMV in chronic periodontitis: a prevalence study

Periodontitis is an infectious disease involving specific bacteria and viruses. Herpesviruses believed to play roles in it. The present study examines the presence of Epstein-Barr virus (EBV) and cytomegalovirus (CMV) in subgingival and supragingival plaque of 61 patients with chronic periodontitis and 40 healthy controls. A nested polymerase chain reaction method was used. The clinical parameters, clinical attachment level (CAL), probing depth (PD) and bleeding on probing (BOP) were examined. Prevalence of EBV- 1, EBV-2 and CMV were 73.8%, 4.9% and 59%; respectively. There was no association between the presence of EBV-1, EBV-2 and CMV with bleeding on depth.

Detection and monitoring of human herpesvirus 7 in adult liver transplant patients: impact on clinical course and association with cytomegalovirus

We herein have described HCMV and HHV-7 detection during the follow-up of 29 adult liver recipients in our transplant unit. For basic immunosuppression, the patients received cyclosporine and symptomatic HCMV infection was treated with gancyclovir. The most prevalent etiology for liver transplantation was hepatitis C or alcohol abuse (45% of patients). The laboratory monitoring to 180 days after transplantation was performed by nested-polymerase chain reaction to HCMV or HHV-7. HCMV DNA was detected in 19/29 of patients (65.5%) and HHV-7 DNA, in 14/29 of patients (48.2%). The time-related appearance of HHV-7 and HCMV DNA differed significantly (P = .02); their detection was considered independent (P = .2). The results showed that few patients remained free of HHV-7 or HCMV after liver transplantation, indicating that most patients were actively infected with more then one virus sequentially and not concurrently. Graft dysfunction, fever, gastrointestinal system abnormalities, and interstitial pneumonitis dominated the clinical pictures. Thirteen of 29 patients (44.8%) developed symptomatic HCMV active infections. The relationship between the detection of HCMV DNA, and HCMV disease development was significant (P = .0004). In HCMV-free patients, no symptoms or significant laboratory findings were linked with HHV-7. However, HHV-7 was frequently detected sequentially after HCMV, and an interaction of HCMV and/or HHV-6 to increase their pathogenic effects could not be excluded. Further studies should be performed including HHV-6 to evaluate the relationship, among beta herpesviruses.

Comparison of serology, antigenemia assay and the polymerase chain reaction for monitoring active cytomegalovirus infections in hematopoietic stem cell transplantation patients

Forty-six allogeneic hematopoietic stem cell transplantation (HSCT) patients were monitored for the presence of CMV antibodies, CMV-DNA and CMV antigens after transplantation. Immunoenzymatic serological tests were used to detect IgM and the increase in CMV IgG antibodies (increase IgG), a nested polymerase chain reaction (N-PCR) was used to detect CMV-DNA, and an antigenemia assay (AGM) was used to detect CMV antigens. The presence of CMV-IgM and/or CMV-increase IgG antibodies was detected in 12/46 (26.1%) patients, with a median time between HSCT and the detection of positive serology of 81.5 days. A positive AGM was detected in 24/46 (52.2%) patients, with a median time between HSCT and antigen detection of 62 days. Two or more consecutive positive N-PCR results were detected in 32/46 (69.5%) patients, with a median time between HSCT and the first positive PCR of 50.5 days. These results confirmed that AGM and mainly PCR are superior to serology for the early diagnosis of CMV infection. Six patients had CMV-IgM and/or CMV-increase IgG with a negative AGM (five cases) or N-PCR assay (one case). In five of these cases the serological markers were detected during the first 100 days after HSCT, the period of highest risk. These findings support the idea that serology may be useful for monitoring CMV infections in HSCT patients, especially when PCR is unavailable.

Real-time PCR assay compared to nested PCR and antigenemia assays for detecting cytomegalovirus reactivation in adult T-cell leukemia-lymphoma patients

We analyzed the efficiency of the quantitative real-time PCR assay for cytomegalovirus (CMV) reactivation in adult T-cell leukemia-lymphoma (ATL) patients and compared the results with those obtained with qualitative nested PCR and antigenemia assays. The viral load obtained by the real-time PCR assay closely paralleled the number of antigen-positive cells obtained with the antigenemia assay. Real-time PCR revealed that a large number of DNA copies could be present even in samples assessed as negative or low in antigen-positive cells (0 to 10 antigen-positive cells/50,000 cells) by antigenemia assay. CMV copy numbers did not differ between the negative and low-antigen-positive groups. When the input concentration for real-time PCR assay was 2,500 to 5,000 copies/ml, the positivity rate for the nested PCR assay was 47.3%, while the positivity rate was more than 90% at an input concentration of >/=50,000 copies/ml. Real-time PCR is more sensitive than the antigenemia and nested PCR assays. Moreover, real-time PCR was able to detect CMV reactivation earlier than the antigenemia and nested PCR assays through the use of longitudinal analysis in four ATL patients with CMV pneumonia. In longitudinal assessments, analysis of the results suggested that a cutoff level of 5,000 copies/ml might be used to initiate treatment. Real-time PCR is more suitable for monitoring CMV reactivation in ATL patients than the antigenemia and nested PCR assays. CMV viral loads of 5,000 copies/ml are proposed as the cutoff for initiating antiviral therapy in ATL patients.

A highly sensitive assay for detection and quantitation of human cytomegalovirus DNA in serum and plasma by PCR and electrochemiluminescence

We describe a diagnostic PCR assay (D-PCR) and a quantitative PCR assay (Q-PCR) for the detection of human cytomegalovirus (CMV) in plasma and serum. In the D-PCR, DNA was purified from plasma or serum together with internal control (IC) DNA, which monitored both DNA extraction efficiency and PCR efficiency. DNA was subjected to PCR with a single primer pair, and the amount of PCR products was determined by electrochemiluminescence (ECL) in the QPCR System 5000 (Perkin-Elmer) after hybridization with Tris (2,2'-bipyridine) ruthenium (II) chelate-labeled probes. The lower limit of sensitivity of the D-PCR was reached at about 25 CMV particles/ml. Even with extremely low DNA inputs (four molecules of IC DNA/200 microl of plasma), very high yields (near 100%) were reached. DNA extracted from specimens that were CMV positive by the D-PCR was subsequently used in the Q-PCR, which was similar to the D-PCR. The viral load was calculated directly from the ratio of CMV and IC signals obtained by ECL. The Q-PCR assay is quantitative in the range of 100 to 150,000 copies of CMV/ml, independent of the anticoagulant. Interassay variation, intra-assay variation, and interspecimen variation were about 25%, suggesting that the Q-PCR will reliably detect fourfold differences in viral load. Comparison of paired serum and plasma specimens from CMV-infected individuals showed that serum CMV loads were frequently more than 10-fold lower than plasma CMV loads.

PCR detection of DNA specific for Trichosporon species in serum of patients with disseminated trichosporonosis

Deep-seated trichosporonosis is a lethal opportunistic infection that disseminates rapidly and widely in immunocompromised patients, and early diagnosis is crucial for the treatment of this infection. We developed a novel nested-PCR assay that detects DNA specific for clinically important strains of Trichosporon in serum samples from patients with disseminated trichosporonosis. In this assay, two sets of oligonucleotide primers were derived from the sequence of 26S rRNA genes of Trichosporon asahii. The specific fragment was amplified from T. asahii and T. mucoides, but not from other microorganisms, including some other basidiomycetous fungi (Cryptococcus, Malassezia, Rhodotorula, and Sporobolomyces). Target DNA was detected by the nested PCR with as little as 5 fg of the extracted DNA of T. asahii. In a study using 11 clinical samples, the specific fragment was detected by the nested PCR in 64% (7 of 11) of sera from patients with histologically diagnosed disseminated trichosporonosis, while glucuronoxylomannan antigen was detected in only 54% (6 of 11) of the samples. Our new nested-PCR assay using serum samples can be performed repeatedly throughout the course of the disease. In addition, not only can it be used for early diagnosis of trichosporonosis, but it may also be beneficial for monitoring its progress or response to therapy.

A simple and sensitive method for detecting adenovirus in serum and urine

A method to detect shed virus in patients' serum and urine was developed following Ad5CMV-p53 gene transfer via direct tumor injections. The procedure differs from those reported previously in that it first uses polyethylene glycol to precipitate adenoviral particles from patient serum or urine. Adenoviral DNA is then extracted following proteinase K digestion. Finally, polymerase chain reaction (PCR) amplification followed by Southern blot transfer are employed to enhance the limit of detection to less than ten viral particles. The detection limit in a 0.25-ml sample is five viral particles in serum and one viral particle in urine. This procedure is sensitive, reproducible, and can be completed in less than 2 days.

PCR detection of DNA specific for Aspergillus species in serum of patients with invasive aspergillosis

We investigated the possible presence of DNA specific for Aspergillus species in serum samples of patients with invasive aspergillosis (IA) by the nested PCR method. Fourteen strains of fungi including 5 strains of Aspergillus species and 10 strains of common bacteria were used for examination of specificity and sensitivity of the nested PCR. Two sets of oligonucleotide primers were derived from the sequence of the variable regions V7 to V9 of the 18S rRNA genes of Aspergillus fumigatus. The specific fragment was amplified from five strains of Aspergillus species in the single and nested PCR but not from other microorganisms. Target DNA was detected by the nested PCR with as little as 50 fg of the extracted DNA of A. fumigatus. We investigated the detection of DNA specific for Aspergillus species in serum samples of a murine model of aspergillosis and 20 patients with IA. The specific fragment was detected by the nested PCR in 71% of serum samples of infected mice and 70% of serum samples of patients with IA, while galactomannan antigen was detected in 43 and 60% of samples, respectively. The high sensitivity and specificity of the nested PCR indicate that the assay can provide early diagnosis with sufficient accuracy to be clinically useful for immunocompromised patients with IA.