Varicella zoster infection in the immunocompromised child.

PURPOSE: To describe varicella zoster virus infection in the immunocompromised child and provide guidelines to decrease the risk of infection and complications for these children. POPULATION: Children infected with varicella zoster virus, particularly those with a compromised immune system. CONCLUSIONS: Varicella zoster virus infection can have serious consequences for children with malignancies and infection with the human immunodeficiency virus, as well as children on chronic steroid therapy. PRACTICE IMPLICATIONS: The advanced practice nurse often is responsible for identifying those children at increased risk for VZV infection and its complications and for planning and implementing interventions to decrease the risks to the immunocompromised child.

End joining of genomic DNA and transgene DNA in fertilized mouse eggs.

A linear 5.2-kb HS2/beta-globin construct with an upstream KpnI terminus (4-nucleotide (nt) 3' protruding single strand, PSS) and a downstream SalI terminus (4-nt 5' PSS) was microinjected into fertilized mouse eggs. The injected DNA fragments integrated into the mouse genome primarily as a head-to-tail tandem array. Chromosome/transgene junctions were obtained from seven of eight transgenic animals. All of the junctions occurred in the proximity of a transgene KpnI end; a maximum loss of 8 nt from the transgene terminus was observed. Two of these junctions completely preserved the 4-nt KpnI 3' PSS. Transgene/transgene junctions from two animals were analyzed. SalI/KpnI junctions that completely preserved both the SalI 5' PSS and the KpnI 3' PSS were found in each animal. These are the first examples of complete nt preservation at junctions formed between a 5' PSS terminus and a 3' PSS terminus in transgenic mice. The data are consistent with the fill-in model of Thode et al. [Cell 60 (1990) 921-928] in which alignment proteins juxtapose 5' PSS and 3' PSS termini; DNA polymerase then utilizes the recessed 3'-OH of the 5' PSS terminus as a primer to synthesize DNA across the gap. This mechanism results in the formation of junctions with no loss of sequence. The results described in the present paper suggest that this mechanism may be involved in the formation of junctions in transgenic mice.

Autonomous, erythroid-specific DNase I hypersensitive site formed by human beta-globin locus control region (LCR) 5' HS 2 in transgenic mice.

The human beta-globin locus control region (LCR) is composed of four erythroid-specific, DNase I hypersensitive (HS) sites that are located 6 to 18 kb upstream of the epsilon-globin gene. The beta-globin LCR appears to have two major functions. First, the sequences "open" a chromosomal domain that includes the epsilon-, gamma-, and beta-globin genes and, second, the LCR directs high-level, erythroid-specific expression of each globin gene family member. An LCR subfragment containing only 5' HS 2 can confer these properties on a linked beta-globin gene. To determine whether 5' HS 2 can form an erythroid-specific, DNase I hypersensitive site in the absence of a linked globin gene, a 1.9-kb DNA fragment containing this site was injected into fertilized mouse eggs and DNase I hypersensitivity was analyzed in the animals that developed. In 9 of 10 transgenic mouse lines, the human 5' HS 2 fragment formed a DNase I hypersensitive site in fetal liver but not in fetal brain. These results suggest that human 5' HS 2 can function autonomously to organize an open chromatin domain specifically in erythroid cells.

Human beta-globin locus control region: analysis of the 5' DNase I hypersensitive site HS 2 in transgenic mice.

The human beta-globin locus control region (LCR) is essential for high-level expression of human epsilon-, gamma-, and beta-globin genes. Developmentally stable DNase I hypersensitive sites (designated HS) mark sequences within this region that are important for LCR activity. A 1.9-kilobase (kb) fragment containing the 5' HS 2 site enhances human beta-globin gene expression 100-fold in transgenic mice and also confers position-independent expression. To further define important sequences within this region, deletion mutations of the 1.9-kb fragment were introduced upstream of the human beta-globin gene, and the constructs were tested for activity in transgenic mice. Although enhancer activity was gradually lost with deletions of both 5' and 3' sequences, a 373-base-pair (bp) fragment retained the ability to confer relative position-independent expression. Three prominent DNase I footprints were observed in this region with extracts from the human erythroleukemia cell line K-562, one of which contained duplicated binding sites for transcription factor AP-1 (activator protein 1). When the 1.9-kb fragment containing an 18-bp deletion of the AP-1 binding sites was tested in transgenic mice, enhancer activity decreased 20-fold but position-independent expression was retained.

Enzyme immunoassay for direct detection of influenza type A and adenovirus antigens in clinical specimens.

Detection of viral antigens in specimens without prior cultivation in cell culture provides the most rapid method for specific viral diagnosis. A solid-phase, double-antibody enzyme immunoassay was developed for this purpose and tested with clinical specimens containing influenza type A and adenovirus. Polystyrene microtiter wells were the solid phase and were coated with virus-specific guinea pig immunoglobulins. Specimens were added, and bound viral antigens were detected by addition of virus-specific rabbit immunoglobulins followed by enzyme-labeled goat antirabbit immunoglobulin G. Two methods of labeling goat anti-rabbit immunoglobulin G with horseradish peroxidase were investigated: covalent attachment and a noncovalent, immunological binding of antibody to enzyme, the peroxidase-antiperoxidase method. Both methods of labeling resulted in assays that could detect 10(3.5) 50% tissue culture infectious doses of influenza type A and 10(3.8) 50% tissue culture infectious doses of adenovirus. Equal sensitivity was noted with alkaline phosphatase-labeled goat anti-rabbit immunoglobulin G. An increase in sensitivity of three- to sixfold was achieved when virus-specific rabbit immunoglobulins and conjugate were diluted in 1% gelatin. The solid-phase, double-antibody enzyme immunoassay detected influenza type A and adenovirus in isolation-positive clinical specimens with 53% (21/40) and 62% (13/21) efficiency, respectively. The solid-phase, double-antibody enzyme immunoassay has considerable potential as a practical and rapid method for detection of respiratory viral antigens in nasal wash and throat swab specimens. For optimal value, however, greater sensitivity than was provided by the present methods is desirable.