Microbiological characterization of porcine fetal islet-like cell clusters for intended clinical xenografting

Abstract: A major concern in animal-to-man transplantation is the risk of transferring microorganisms from an animal to a patient. For this reason, before transplanting the porcine fetal pancreas to diabetic patients, the pregnant sows and the tissue to be transplanted—i.e., fetal islet-like cell clusters (ICC) prepared by collagenase digestion and cell culture—were subjected to a comprehensive microbiological screening program. Serological testing of the pregnant sows revealed antibodies to Leptospira interrogans (2/59 sows, 3%) and Aspergillus fumigatus (23/41, 56%). However, there was no evidence of colonization of the animals with these organisms. Serological testing for a multitude of other microorganisms was negative. Growth of bacteria was found in 4% of the specimens recovered from the endometrium and in 31% of those from the amniotic fluid. However, none of these bacterial species was recovered in the culture dishes containing ICC. A few samples taken from the culture dishes (2/53, 4%) revealed growth of bacteria, but no viruses, fungi, or mycoplasmas were detected. In nude mice that had carried ICC under the kidney capsule for 9 to 23 months, various lesions were observed, but none of them was due to the implanted porcine tissue. Microscopic examination of the mouse brains revealed no prion-related alterations. If porcine tissue is to be transplanted into humans, a stringent microbiological screening program must be followed. The program used by us makes possible the weeding out of seropositive animals, as required, and the exclusion of contaminated tissue.     

Rapid detection of cytomegalovirus DNA and RNA in blood of renal transplant patients by in vitro enzymatic amplification.

Cytomegalovirus infection causes significant morbidity and mortality in renal transplant patients. The only marker of CMV infection that appears to correlate with the development of symptomatic illness is viremia. However, CMV grows slowly in tissue culture, requiring 2-6 weeks of incubation for detection of characteristic cytopathic effect. The efficacy of antiviral therapy for CMV may be improved by earlier detection of viremia and institution of antiviral therapy. We performed amplification of CMV DNA and RNA from peripheral blood of renal transplant patients using the polymerase chain reaction (PCR) technique. We consistently detected CMV DNA by PCR earlier than CMV was detected by culture. Detection of CMV RNA in one patient confirmed the presence of actively replicating virus in peripheral blood. Amplification of peripheral blood from healthy CMV-seropositive and seronegative individuals, and from seropositive renal transplant patients without evidence of active CMV disease, was consistently negative. These preliminary data indicate that PCR may provide a means for earlier diagnosis of CMV viremia. Future prospective studies should determine if early detection of CMV DNA by PCR in peripheral blood does predict viremia and symptomatic illness, and if earlier institution of antiviral therapy based on PCR results improves outcome for the CMV-infected transplanted patient.     

Relationship between the occurrence of virus in plasma and cerebrospinal fluid of HIV-1 infected individuals

Attempts to isolate human immunodeficiency virus type 1 (HIV-1) were carried out on cerebrospinal fluid (CSF) and blood plasma samples from 111 HIV-1 infected subjects in various stages of infection. HIV-1 was recovered at a low rate from CSF of persons with normal immunological parameters but frequently from patients with abnormal values, in all stages of immune system involvement. Isolation from plasma was positive in the majority of the patients, in all stages of infection, with a frequency that was related to the degree of immunodeficiency. HIV-1 could be recovered from the CSF of most patients (74%) with viremia when 85 paired specimens of 58 patients were analyzed. By contrast, HIV-1 was isolated from CSF, but not from plasma, in one case only. HIV-1 p24 antigen measured by an enzyme-linked immunosorbent assay (ELISA) was detectable in only four CSF samples compared with 15 serum samples in paired specimens. These findings indicate that most patients with HIV-1 infection have circulating cell-free infectious virus in the blood and simultaneously demonstrable HIV-1 in the CSF. Replication of HIV-1 exclusively in the central nervous system (CNS) appears to be a rare event.     

Enterovirus IgM detection: specificity of mu-antibody-capture radioimmunoassays using virions and procapsids of Coxsackie B virus

A predominantly type-specific mu-capture radioimmunoassay (RIA) of IgM antibodies to Coxsackie B1-B5 (CB1-CB5) viruses was previously described (Frisk et al., 1984). The present study is concerned with the specificity of this assay, using as antigen different strains of one serotype (CB5) and procapsids of two serotypes (CB3 and CB5). Eight strains of CB5 virions were tested against acute and/or convalescent sera from 10 patients from whom CB5 had been isolated. Seven patients' sera were tested against their own strain. The frequency of IgM-positive patients varied from 9 of 10 (90%) to 5 of 10 (50%). In three cases the highest titres were obtained with the patients' own strain. When sera from patients with other enterovirus infections were tested against the CB5 strains, heterotypic titres were obtained to a certain extent (0-15.6%). The strains giving a high frequency of homotypic titres varied concerning heterotypic reactions. It is concluded that the choice of strain is important if a high frequency of homotypic titres with no or only a few heterotypic reactions is to be obtained. When procapsids were used as antigen, both homotypic and heterotypic titres were seen to a large extent. All patients with homotypic IgM against CB3 or CB5 virions showed IgM against the CB3 or the CB5 procapsids, respectively. When sera from patients with other enterovirus infections were tested, IgM was found in 54 of 93 patients (58%) with use of the CB3 procapsid and in 52 of 87 patients (60%) with the CB5 procapsid. It was often not the same patients who showed IgM against the two different procapsids. When both procapsids were used, IgM positivity was found in 62 of 81 patients (77%) with other enterovirus infections. It is concluded that the use of two or more procapsids in combination is of value for the diagnosis of a recent or current enterovirus infection.     

Feeding practices of HIV-1-infected mothers: the role of counsellors

In this issue of Acta Paediatrica, Chopra et al. report that voluntary counselling is central to preparing mothers for making a proper informed choice about adequate feeding practices to prevent their infants from acquiring HIV infection. The recommendations given and the way in which counselling is performed are the most important determinants of a mother's decision about how to feed her infant. In this article, we summarize the main arguments for and against breastfeeding by HIV-infected mothers. Conclusions: Further studies are needed to determine the alternatives to breastfeeding in countries where there is no access to safe formula feeding or to antiretroviral drugs. HIV-positive mothers should be made aware of the available feeding alternatives through adequate counselling from properly trained persons.     

Regular pattern of respiratory syncytial virus and rotavirus infections and relation to weather in Stockholm, 1984–1993

Objective: To seek the possible epidemiologic relationship between the two dominant pediatric infectious agents, respiratory syncytial virus (RSV) and rotavirus, and to analyze the relationship of RSV to influenza virus infections and climate.
Methods: In the laboratory register, we retrospectively identified pediatric cases less than 5 years of age from the period 1984–93 (including the winter of 1994). RSV was diagnosed by immunofluorescence in nasopharyngeal samples and rotavirus infections by electron microscopy of feces.
Results: We observed a regular and significant pattern of early RSV epidemics (December to February), alternating every other year with later ones (March to April). There were twice as many hospital admissions during early compared to late epidemics. There was a similar but reverse pattern of early and late rotavirus seasons. Influenza A virus outbreaks occurred during the same period as early RSV epidemics. Several weather factors, such as temperature, precipitation, wind force and humidity were analyzed in relation to RSV epidemics without disclosing an important relationship. Cloudiness was, however, found to be associated with RSV peaks.
Conclusions: The possibility of predicting RSV epidemics may be useful for medical planning.