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Biomedical subjects

G Gerna

Publications and source records attributed to G Gerna.

At least 181 records · Page 10Linked to original sources
PubMed1980

Serodiagnosis of respiratory synctial virus infections in infants and young children by the immunoperoxidse technique.

The immunoperoxidase antibody (IPA) technique was used to develop two new tests for serodiagnosis of respiratory syncytial virus infections: a microneutralization test based on the reduction of the number of infected cells and an IPA test for determination of virus-specific immunoglobulin G (IgG). Neutralizing antibody was determined both in the presence and absence of complement. In a group of 24 infants and young childres, ages less than 1 to 36 months, with acute respiratory syncytial virus infection, serodiagnosis was made by the IPA-IgG test in 20 cases, by neutralization test with addition of complement in 19 cases, and by neutralization test without addition of complement in 17 cases. Complement fixation detected only 12 cases of infection. All four cases not serologically diagnosed were infants less than 1 month old. Neutralization test antibody titers in the presence of complement were usually 4- to 16-fold higher than titers obtained without addition of complement. Both IPA-IgG and neutralization test (in the presence of complement) appear very efficient in serologically detecting respiratory syncytial virus infections in infants older than 1 month and give rapid results (IPA-IgG takes 2 h to complete, and the neutralization test takes 24 h). However, IPA-IgG is simpler to perform.

Antibodies, Viral↗
PubMed1979

Antibody to early antigens of varicella-zoster virus during varicella and zoster.

IgG antibody to the early antigens of varicella-zoster virus (VZV) was studied during both varicella and zoster by the indirect immunoperoxidase antibody technique. In parallel, complement-fixing, immune-adherence hemagglutinating, IgG, and IgM antibodies to VZV were studied. In both varicella and zoster infections, antibody to the early antigens of VZV appeared three to five days after onset of infection, reached a peak during the second week, and progressively decreased in titer until it disappeared, usually within two months. This antibody usually appeared slightly later than IgG or IgM antibody and grossly correlated with IgM antibody in varicella. In zoster infections, IgM antibody to VZV was not found by the immune-adherence hemagglutination assay at a titer of greater than or equal to 1:4, whereas antibody to the early antigens showed a curve similar to that found in varicella. It is suggested that antibody to the early antigens of VZV be considered as a marker of acute VZV infection, which is associated with a specific and significant IgM antibody response in varicella but not in zoster.

Adolescent↗
PubMed1978

Seroepidemiologic study of human coronavirus OC43 infections in Italy.

Human Coronavirus OC43 from suckling mouse brain (SMB) suspension has been adapted to grow in human embryonic lung fibroblast cell cultures. Complement-fixing and hemagglutinating antigens were prepared from infected cell cultures and used in parallel with the same antigens from SMB for a study of the prevalence of OC43 antibody in Northern Italy as well as for the serodiagnosis of recent OC43 infections and reinfections. Results show (i) a higher sensitivity of the hemagglutination-inhibition as compared to the complement fixation test both for antibody detection in seroepidemiological studies and serodiagnosis of acute infections, (ii) a high prevalence of OC43 antibody in Northern Italy, so that only exceptionally are people older than 12 years seronegative, (iii) a high rate of OC43 reinfections during the winter-spring season 1976/77 in a population sample with preexisting antibody (iv) a good quality of reagents prepared from cell cultures, and hence free of contaminating mouse viruses, such as mouse hepatitis virus.

Adolescent↗
PubMed1978

Immunoglobulin G to virus-specific early antigens in congenital, primary, and reactivated human cytomegalovirus infections.

Immunoglobulin G antibody to human cytomegalovirus (CMV)-specific early antigens (EA-Ab) was determined by the immunoperoxidase antibody technique in several cases of congenital, primary, and reactivated CMV infections. Mothers of congenitally infected infants and a group of leukemic children and pregnant women were also studied. In 11 cases of congenital infection, CMV EA-Ab was always associated with CMV excretion whether immunoglobulin M antibody was present or not. Nine mothers of congenitally infected infants had CMV EA-Ab for several months after delivery, but association with CMV elimination was not established when urine and/or saliva were tested for virus isolation. In all nine cases of primary CMV infection, CMV EA-Ab was present, and in five its detection was associated with CMV isolation. In one case, disappearance of EA-Ab occurred when virus excretion ceased. In five cases of reactivated CMV infections, a consistent association between CMV EA-Ab and virus isolation was found. Six of 31 leukemia children had CMV EA-Ab, and virus was isolated from 3 of these. Four of 28 pregnant women showed EA-Ab in their serum, but tests for isolation were not done. These data suggest that CMV EA-Ab is not a marker of a current primary CMV infection, as previously reported, but a marker of an active CMV replication which can take place in primary as well as in congenital and reactivated CMV infections.

Adult↗
PubMed1977

Type specificity and use of human sera for rapid typing of herpes simplex virus isolates by an indirect peroxidase-labeled antibody technique: a comparison with three other methods.

Human sera from patients showing seroconversion following a primary herpes simplex virus type 1 (HSV-1) or HSV type 2 (HSV-2) infection, as well as 19S and 7S fractions obtained from the same sera, have been used for typing 191 HSV isolates by an indirect peroxidase-labeled antibody (PLA) method. Typing has also been performed on all of the isolates using a microneutralization (MN) and the indirect hemagglutination (IHA) inhibition test. Furthermore, 30 isolates have been typed by a plaque method. Results obtained with the PLA method was in complete agreement with those of the other two procedures. The PLA method is rapid and simple, offers easy interpretation and a permanent record of results.

Antibody Specificity↗
PubMed1977

Techniques for typing Herpesvirus hominis antibody: a comparison of inhibition of peroxidase-labelled antibody staining with inhibition of indirect haemagglutination and with microneutralisation.

A new technique based upon the inhibition of the peroxidase-labelled antibody staining (PLAS) has been used to type Herpesvirus hominis (HVH) antibodies in four groups of human sera taken from patients with one or both types of HVH infection and in mixtures of different proportions of type 1 and type 2 antisera. The results were compared with those of the microneutralisation (MN) test and the indirect haemagglutination (IHA) inhibition test. The sensitivity and specificity of the three methods were identical for sera containing only one type of HVH antibody. The MN test was slightly more sensitive than the other tests for detecting small amounts of HVH-1 antibody mixed with large amounts of HVH-2 antibody. Nevertheless, the PLAS inhibition technique was far more rapid and it would seem a satisfactory alternative to the IHA inhibition test for HVH antibody typing.

Antibodies, Viral↗
PubMed1977

Rapid detection of human cytomegalovirus and herpesvirus hominis IgM antibody by the immunoperoxidase technique.

Immunoglobulin M (IgM) to human cytomegalovirus (CMV) and herpesvirus hominis (HVH, types 1 and 2) has been searched for in a group of patients with congenital and recent CMV and HVH infections and also in a group of patients with remote CMV and recurrent HVH infections, using the immunoperoxidase antibody technique (IPA) as compared to a technique using sucrose density gradient differential centrifugation. Both techniques detected the same positive samples. High IgM antibody titers (1:32-1:512) were observed in all cases of primary CMV and HVH infection, whereas low titers (1:8-1:16) were found in congenital infections. The IPA technique is sensitive, specific and useful for rapid diagnosis of recent and congenital CMV and HVH infections.

Adult↗
PubMed1976

[Distribution of HB s Ag subtypes in a sample of acute viral hepatitis of type B in Northern Italy].

82 HBsAg from acute hepatitis B patients living in Northern Italy were subtyped. HBsAg has been detected by immunodiffusion (ID), electrosyneresis (ES), complement fixation (CF) and radioimmunoassay (RIA, Kit Ausria I and II, Abbott). Subtyping was performed by ES in 50 and by ID in 30 of the 82 assayed sera. An higher frequency of ayw subtype (83,1%) in comparison with adw subtype (16,9%) has been observed. No difference was found between adw and ayw subtypes analyzed as far as geographic-ethnic characters, incubation time, course and prognosis of the disease or the biohumoral indices. No patient was found to have both y and d specificities and so r determinant was never found.

Acute Disease↗
PubMed1976

The immunoperoxidase technique for rapid human cytomegalovirus identification.

Sixteen cytomegalovirus (CMV) isolates from both ill and healthy patients were identified by the immunoperoxidase technique (IP). CMV detection was accomplished by direct examination of the primary isolate using either direct (DIP) or indirect immunoperoxidase (IIP) techniques. In thirteen of the isolates, confirmation of identification was achieved by indirect immunofluorescence (IFA) and by demonstration of herpes particles by electron microscopy (EM). Further, in four cases of non-CMV alterations in the tissue culture which might be confused with actual infection, the IP test was negative as were the confirmatory tests. The IIP is preferred over the DIP test since the latter shows a certain amount of background stain of uninfected cells. Tissue culture cells showing focal CMV cytopathic effect contained both nuclear and cytoplasmic inclusions stained by IP technique. Nonspecific staining was associated with cytoplasmic inclusion bodies. The IP technique can detect individual cell CMV infection at 24 hours when EM reveals only unenveloped viral particles. It is sensitive, specific, and allows direct identification of infected cells in the primary isolate in as little as 90 minutes. Furthermore, it can be performed in standard isolation tissue culture tubes, whereas IFA requires the transfer of the infected cells onto slides or the routine use of Leighton tubes.

Adult↗
PubMed1976

Rubella antibody assay by the immunoperoxidase technique: comparison with the hemagglutination inhibition test for determination of immune status.

The rubella immune status of 128 young women was determined with two assays for rubella antibody, the immunoperoxidase technique and the hemagglutination inhibition test. Comparison of the results of these techniques showed agreement in 125 cases (110 positive and 15 negative). Positive results were obtained for one woman only by the immunoperoxidase assay and for two women only by the hemagglutination inhibition test; all three of these women had a minimal titer of rubella antibody of 1:16. The sensitivity of the immunoperoxidase test was comparable to that of the hemagglutination inhibition test, and the specificity of the former test was verified. The peroxidase-labeled antibody technique is easier to perform than the hemagglutination inhibition test and is less time-consuming since sera do not require prior treatment and results can be obtained in as little as 90 min.

Antibodies, Viral↗
PubMed1976

Immunoperoxidase technique for detection of antibodies to human cytomegalovirus.

The indirect immunoperoxidase antibody technique (IPA) has been applied to determine immunoglobulin (Ig)G to humans cytomegalovirus (CMV) antibodies in 114 blood donor sera, four cases of congenital cytomegalic inclusion disease, and four cases of acquired CMV infection. The results have been compared with those obtained with the CMV complement fixation (CF) test and indirect fluorescent antibody technique (IFA) for broad spectrum CMV antibody (sigmaAb) detection. IgG antibody has been detected by both CF and IPA. In healthy adult people IPA titers are usually higher than CF titers. In addition, IFA sigmaAb titers are generally higher than CF titers. Some sera negative by CF and IPA are positive at low dilutions by IFA sigmaAb antibody determination, due to the detection of small amounts of IgA or noncomplement-fixing IgG. Nonspecific results seem unlikely, since only nuclear inclusion fluorescence was interpreted as specific, as demonstrated by blocking tests. In acute CMV infection, the IFA sigmaAb and IPA IgG titers are essentially the same, except during the first weeks of infection, when IFA titers are higher and IgM is detectable. No cross-reactivity with other herpes group viruses, herpes simplex and varicella-zoster, was observed. Although some problems of nonspecific staining of cytoplasmic inclusions are shared by both methods, the IPA technique seems to possess the same degree of sensitivity and specificity as the IFA technique, but interpretation is easier and various procedural steps can be delayed without the technical problems associated with fluorescence microscopy.

Adult↗
PubMed1976

Varicella-zoster plaque assay and plaque reduction neutralization test by the immunoperoxidase technique.

A new plaque assay for the quantitation of varicella-zoster virus and a plaque reduction neutralization test for the determination of neutralizing antibody titer have been developed using the indirect immunoperoxidase technique. As compared with the classical plaque assay using a solid overlay, the test gives earlier results since plaque counting can be performed on day 3 after the inoculation of cell cultures. In six patients with zoster infection, neutralizing antibody titers ranged from 1:20 to 1:40 before the onset of infection and reached high levels (1:320 to 1:5,120) during the convalescent phase of the disease. Complement-fixing (CF) titers were all negative (less than 1:8) in prezoster serum samples from the same patients and ranged from 1:128 to 1:2,048 in the convalescent-phase sera. In the two cases in which late serum samples were available, neutralizing antibody titers matched the preillness levels, whereas CF titers dropped to undetectable levels. Neither neutralizing nor CF antibody was detected in two sera from individuals with no history of varicella-zoster infection. No differences in virus titers or neutralizing antibody titers were observed between the immunoperoxidase and the classical plaque assays. The appropriate characterization of reagent specificity is required before routine application of the test.

Antibodies, Viral↗
PubMed1975

[Determination of anti-cytomegalovirus antibodies by the immunoperoxidase method: comparison with the methods of complement fixation and immunofluorescence].

Indirect immunoperoxidase technique (IIP) has been employed for determination of IgG antibody titer to cytomegalovirus (CMV) in sera from 110 blood donors. Titers have been compared with complement fixation (CF) and indirect fluorescent antibody (IFA) technique titers, the latter being applied to determination of all specific antibody classes. Within variability range of the quality of reagents employed in different tests, it seems reasonable to conclude IIP technique is as sensitive as IFA and much more sensitive than CF test. Considering CF test is able to detect only IgG antibody, the advantage of using immunohistochemical techniques is obvious. Moreover IIP does not need fluorescence microscope and results reading is easier and can be delayed. Non-specific staining of Golgi area is shared by both techniques, but endpoint determination has to take into account only the nuclear virus-specific inclusion labelling.

Antibodies, Viral↗