Three Novel Mutations in the PHEX Gene in Chinese Subjects with Hypophosphatemic Rickets Extends Genotypic Variability

Mutations in the phosphate-regulating endopeptidase homolog, X-linked, gene (PHEX), which encodes a zinc-dependent endopeptidase that is involved in bone mineralization and renal phosphate reabsorption, cause the most common form of hypophosphatemic rickets, X-linked hypophosphatemic rickets (XLH). The distribution of PHEX mutations is extensive, but few mutations have been identified in Chinese with XLH. We extracted genomic DNA and total RNA from leukocytes obtained from nine unrelated Chinese subjects (three males and six females, age range 11–36 years) who were living in Taiwan. The PHEX gene was amplified from DNA by PCR, and the amplicons were directly sequenced. Expression studies were performed by reverse-transcription PCR of leukocyte RNA. Serum levels of FGF23 were significantly greater in the patients than in normal subjects (mean 69.4 ± 18.8 vs. 27.2 ± 8.4 pg/mL, P < 0.005), and eight of the nine patients had elevated levels of FGF23. Germline mutations in the PHEX gene were identified in five of 9 patients, including novel c.1843 delA, donor splice site mutations c.663+2delT and c.1899+2T>A, and two previously reported missense mutations, p.C733Y and p.G579R. These data extend the spectrum of mutations in the PHEX gene in Han Chinese and confirm variability for XLH in Taiwan

Development of a Fluorescence Polarization-Based Diagnostic Assay for Equine Infectious Anemia Virus

The control of equine infectious anemia virus (EIAV) infections of horses has been over the past 20 years based primarily on the identification and elimination of seropositive horses, predominantly by a standardized agar gel immunodiffusion (AGID) assay in centralized reference laboratories. This screening for EIAV-seropositive horses has been to date hindered by the lack of a rapid diagnostic format that can be easily employed in the field. We describe here the development of a rapid solution-phase assay for the presence of serum antibodies to EIAV based on fluorescence polarization (FP) (patent pending). Peptides derived from antigenic regions of EIAV core and envelope proteins were initially screened for their utility as probes in an FP assay to select the best peptide antigen candidates. The FP assay was optimized to detect the presence of EIAV-specific antibodies by a change in the FP of a fluorescein-labeled immunoreactive peptide diagnostic antigen. The most sensitive and specific peptide probe was a peptide corresponding to the immunodominant region of the EIAV transmembrane protein, gp45. This probe was tested for its reactivity in the optimized FP assay with 151 AGID-positive horse sera and 106 AGID-negative serum samples. The results of these studies demonstrated that the FP assay reactivity correlated with reported AGID results in 106 of 106 negative serum samples (100% specificity) and in 135 of 151 positive serum samples (89.4% sensitivity). The FP assay was also found to have a very low background reactivity and to readily detect antibodies produced early in infection (≤3 weeks postinfection). The developed EIAV FP assay is rapid (5 to 20 min) and simple to perform and is equally suitable for use both in the field and in the diagnostic laboratory, thus providing the basis of an improved commercial diagnostic assay for EIAV infection of horses

Lentivirus Lytic Peptide 1 Perturbs both Outer and Inner Membranes of Serratia marcescens

Bis-lentivirus lytic protein 1 (Bis-LLP1) and polymyxin B exhibited similar killing activities against Serratia marcescens. By electron microscopy, bis-LLP1 interacted with the outer and cytoplasmic bacterial membranes, while polymyxin B affected only the outer membrane. The results of standard biochemical probes supported the findings of the electron microscopy studies, suggesting that these antimicrobial peptides have different mechanisms of action