Gregory T. Maine

New developments in the diagnosis of maternal and congenital CMV infection

Recent advances in the screening of pregnant women with Cytomegalovirus (CMV) IgM, CMV IgG and CMV IgG avidity serologic tests, has led to a more accurate diagnosis of CMV infection. When serologic screening is performed early in gestation, it is possible to identify those women at risk of intrauterine transmission of the virus, i.e., those women with a primary CMV infection, who should be enrolled in prenatal diagnosis. The use of quantitative PCR on amniotic fluid from pregnant women at 21–22 weeks of gestation in prenatal diagnosis is an effective diagnostic tool to distinguish between CMV infection and CMV disease in the fetus and newborn. Quantitative PCR on peripheral blood leukocytes from CMV infected newborns can be used to monitor viral load, especially during treatment with ganciclovir. These advances in serology and quantitative virology should lead to more accurate diagnosis of maternal and congenital CMV infection.

Evaluation of the Abbott AxSYM cytomegalovirus (CMV) immunoglobulin M (IgM) assay in conjunction with other CMV IgM tests and a CMV IgG avidity assay

ABSTRACT The measurement of the avidity of cytomegalovirus (CMV) immunoglobulin G (IgG) antibodies has been shown by several investigators to be useful in identifying and excluding primary CMV infections in pregnant women. In this work, we examined the diagnostic utility of reflex testing of CMV IgM-positive specimens from pregnant women by using a CMV IgG avidity assay. The utility of this approach was directly dependent on the sensitivity of the CMV IgM assay employed during the initial screen. The higher initial reactivity rate of the AxSYM CMV IgM assay was necessary in order to detect CMV IgM in specimens containing low-avidity CMV IgG antibodies, indicative of a primary CMV infection, which other CMV IgM assays (Behring, Vidas, Captia, and Eurogenetics) fail to detect in some cases. The use of the AxSYM CMV IgM assay, followed by an avidity test, should result in more accurate diagnosis of CMV infection in pregnant women.

Quantitative immunolocalization of a P29 protein (GRA7), a new antigen of toxoplasma gondii.

Ultrastructural localization of a P29 protein of Toxoplasma gondii was examined on thin sections by an immunogold technique using a P29 antigen-specific monoclonal antibody (5-241-178). Immunolocalization of the P29 protein in extracellular tachyzoites demonstrated that this antigen was present in the dense granules. Thus, we have identified this P29 antigen as the seventh protein (GRA7) to be localized to the dense granules of T. gondii. P29 immunolocalization in intracellular tachyzoites demonstrated association of this antigen with the parasite membrane complex, tubular elements of the intravacuolar network, and with the parasitophorous vacuolar membrane. Our immunolabeling data suggest trafficking of the P29 (GRA7) antigen from the dense granule via the intravacuolar network to the parasitophorous vacuolar membrane on invasion of the tachyzoite into the host cell.

Relationship between IgM Antibody to Human Cytomegalovirus, Virus Load, Donor and Recipient Serostatus, and Administration of Methylprednisolone as Risk Factors for Cytomegalovirus Disease after Liver Transplantation

A retrospective study was performed on a selected cohort of 40 liver transplant recipients derived from the previous prospective follow-up of 162 liver transplant patients. The criterion for selection of this cohort was the presence of human cytomegalovirus (HCMV) DNAemia after transplantation, as determined by qualitative polymerase chain reaction (PCR). These 40 patients were followed longitudinally by quantitative PCR and by the new recombinant antigen-based AxSYM immunoassay for IgM to HCMV. The detection of IgM to CMV after transplantation was significantly associated with the development of HCMV disease in patients who had evidence of active HCMV replication in the blood by PCR (P=.01). On the basis of multivariate logistic regression analyses, the maximum titer of IgM detected after transplantation was a risk factor that was independent of augmented methylprednisolone and donor seropositivity. However, in multivariate analyses, elevated virus load continued to be the predominant risk factor for progression to HCMV disease.

Validation of an automated immunoglobulin G–only cytomegalovirus (CMV) antibody screening assay and an assessment of the risk of transfusion transmitted CMV from seronegative blood

BACKGROUND: Cytomegalovirus (CMV) antibody donor screening assays have predominantly included both immunoglobulin G (IgG) and immunoglobulin M (IgM) detection. However, since in the majority of cases both CMV IgG and IgM are detected concomitantly during early seroconversion, CMV assays based only on IgG are now widely applied for donor screening.

Clinical evaluation of a new recombinant antigen-based cytomegalovirus immunoglobulin M immunoassay in liver transplant recipients

BACKGROUND Human cytomegalovirus (CMV) is a significant cause of morbidity and mortality among transplant recipients. Monitoring transplant recipients by CMV IgM serology has been questioned by several studies due to the reported insensitivity of serologic tests relative to antigen detection methods. METHODS In this retrospective study, we have evaluated the performance of the new recombinant antigen-based Abbott AxSYM CMV IgM assay and compared it with CMV culture technique in a cohort of 40 liver transplant recipients who did not receive antiviral prophylaxis. RESULTS The sensitivity, specificity, and positive and negative predictive values for detection of CMV disease by the AxSYM CMV IgM assay were 90.0%, 60.0%, 69.2%, and 85.7%, respectively, and by culture the values were 100%, 55.0%, 69.0%, and 100%, respectively. Detection of CMV IgM occurred before or at the time of CMV disease in only R+ recipients. CONCLUSION Although this assay is a sensitive test for CMV-specific IgM, detection of CMV IgM preceded detection of virus by culture in patients only when the liver transplant recipient was CMV immune before transplantation (R+).

Kinetics of CMV seroconversion in a Swiss pregnant women population.

Retrospective evaluation of the kinetics of cytomegalovirus (CMV) seroconversion with CMV IgM, IgG, and IgG avidity assays, in a Swiss pregnant women population, has shown that the current published CMV serologic diagnostic algorithms were valid and fit for use. In 19% of the cases analyzed, CMV-specific IgM was detected before IgG.