1/4. acyclovir-resistant bilateral keratitis associated with mutations in the HSV-1 thymidine kinase gene.PURPOSE: To evaluate the contribution of molecular methods for the diagnosis of an acyclovir-resistant HSV-1 bilateral keratitis in an AIDS patient and to report a new point mutation in the nucleotide sequence of the thymidine kinase (tk) gene involved. methods: A 31 year old hiv-positive female presented with severe, active, bilateral and sight-threatening keratitis of 6 months duration, which was treated unsuccessfully with acyclovir. After corneal biopsy, samples were analysed by standard virological procedures, in situ hybridization, and PCR. The tk gene was cloned and subsequently sequenced. RESULTS: Conventional virological methods remained inconclusive. However, in situ hybridization and PCR rapidly confirmed the diagnosis of HSV-1 keratitis. The tk gene sequence revealed the presence of five variations previously described in two reference strains, but also a new point mutation at nucleotide position 431 which leads to an amino-acid change at position 144 that supported the hypothesis of a putatively altered functional form of the enzyme. Intravenous foscarnet treatment in an induction regimen was effective and cicatrization occurred within 3 weeks. CONCLUSIONS: PCR and in situ hybridization are effective and powerful techniques when other virological procedures are non-contributive, particularly in immunocompromised patients previously treated with antiviral drugs. The new point mutation identified in the tk gene may be associated with resistance to acyclovir.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/4. Cytological diagnosis of herpesvirus keratitis by means of in situ hybridization: report of a case.Typical herpesvirus keratitis that developed in a 12-year-old boy was initially diagnosed cytologically by the Papanicolaou method demonstrating the 'ground-glass' appearance of the nuclei with multinucleated syncytial cells. Subsequently, the in situ hybridization technique was applied to identify the herpes simplex virus (HSV) dna in the Papanicolaoudestained cellular samples. Positive hybridization was found with intense staining for the HSV dna in the nuclei of cells having a 'ground-glass' appearance. in situ hybridization has been shown to be a useful technique for the identification of HSV in corneal scrapes, and similar studies may be carried out in cellular samples from the other body sites.- - - - - - - - - - ranking = 2.3333333333333keywords = hybridization (Clic here for more details about this article) |
3/4. Possible role of herpes simplex virus in the origin of Posner-Schlossman syndrome.PURPOSE/methods: We conducted this study to determine if the herpesviruses are possible etiologic agents in Posner-Schlossman syndrome. We aspirated aqueous humor samples from patients during acute attacks of the syndrome. Ten normal aqueous humor specimens from patients undergoing cataract surgery were used as controls. dna was extracted and subjected to polymerase chain reaction amplification and Southern blot hybridization. RESULTS/CONCLUSION: All three specimens were positive for amplified genomic fragments of herpes simplex virus and negative for varicella-zoster virus and cytomegalovirus. Ten normal aqueous specimens were negative for all three. herpes simplex virus may play a role in the origin of Posner-Schlossman syndrome.- - - - - - - - - - ranking = 0.33333333333333keywords = hybridization (Clic here for more details about this article) |
4/4. Direct identification of herpes simplex virus type-1 in human corneal tissue. Methodology and application of in situ dna hybridization technique.The definitive diagnosis and determination of recurrence of herpes simplex keratitis are still difficult in clinical ophthalmology. At present, isolation of virus by tissue culture is perhaps the best method for establishing a specific aetiological diagnosis of viral infection. But due to its complicated and time-consuming procedures, the application of tissue culture for virus isolation in clinical work is still limited. In situ dna hybridization is a specific and quick technique for directly detecting genetic materials, dna and rna, of viruses. In this study, this technique was used to identify herpes simplex virus type 1 from a patient's cornea suffered from recurrent herpetic keratitis. The technique offers a convenient and specific method for clinicians to make a definitive diagnosis and differential diagnosis of viral infectious diseases. The advantages and disadvantages of other different methods available for viral diagnosis, such as light and electron microscopy and immunohistochemistry were discussed with an emphasis on in situ dna hybridization.- - - - - - - - - - ranking = 2keywords = hybridization (Clic here for more details about this article) |