The impact of the pandemic influenza A(H1N1) 2009 virus on seasonal influenza A viruses in the southern hemisphere, 2009.

Data collected over winter 2009 by five World Health Organisation National Influenza Centres in the southern hemisphere were used to examine the circulation of pandemic and seasonal influenza A strains during the first pandemic wave in the southern hemisphere.There is compelling evidence that the pandemic influenza A(H1N1) 2009 virus significantly displaced seasonal influenza A(H1N1) and, to a lesser extent, A(H3N2) viruses circulating in the southern hemisphere. Complete replacement of seasonal influenza A strains, however, was not observed during the first pandemic wave.

Congenital varicella syndrome diagnosed by polymerase chain reaction--scarring of the spinal cord, not the skin.

A term infant with congenital varicella syndrome (CVS) is reported. Monoplegia of the left arm and paraplegia were present with no evidence of dermatomal skin scarring. Following death at 12 days of age, autopsy documented severe atrophy and gliosis of the spinal cord. Testing for varicella-zoster virus by the polymerase chain reaction method on brain tissue was positive. This case extends the current understanding of the clinical and pathological features of CVS.

Improving permissive infection of human cytomegalovirus in cell culture.

Changes in human cytomegalovirus (HCMV) titre occurring under different conditions were studied using plaque assay. No significant change in titre was found using primary embryonic fibroblasts or primary foreskin fibroblasts, or with the addition of dexamethasone to the medium. Significant increases in titre were found when standard cultures were pre-incubated in medium containing DEAE-dextran and/or calcium chloride. However, DEAE-dextran and/or calcium chloride had no significant effect on HCMV detection using the shell vial assay, possibly because enhancement affects permissive infection, but not surface expression of viral antigens. DEAE-dextran and calcium chloride can be included in the medium of standard cultures as a means of obtaining higher titres of HCMV, and are particularly useful for isolates that are difficult to culture.

Cytomegalovirus and human herpesvirus 6 both cause viral disease after renal transplantation.

BACKGROUND: Systemic viral disease after renal transplantation, especially after treatment with OKT3 or antithymocyte globulin, has usually been attributed to cytomegalovirus (CMV) infection. Identification of human herpesvirus 6 (HHV6) has raised the possibility that infection or reactivation of this virus may also occur in the same setting. METHODS: We thus examined the incidence of CMV and HHV6 infection in a prospective blinded consecutive series of 30 renal and renal/pancreas transplant patients, 22 of whom received OKT3, antithymocyte globulin, or both. RESULTS: Clinical diagnosis of a viral syndrome was made in 15 patients. Three patients with only HHV6 DNA in urine or serum had fever and abnormal liver function but not neutropenia. All five CMV-seronegative patients who received positive kidneys developed moderate to severe disease with fever and neutropenia but also had HHV6 DNA in urine or serum. Seven CMV-seropositive patients developed disease, mostly after OKT3/antithymocyte globulin, but six shed both CMV and HHV6 in urine or serum. The simultaneous detection of both HHV6 and CMV DNA in either urine or serum was the strongest predictor of disease (and also the severity of disease), with an odds ratio of 99.0 (95% confidence intervals 5.4-1814, P<0.002). CONCLUSION: Most systemic viral disease after renal transplantation may be due to either coinfection or reactivation of CMV and HHV6 together. A wider understanding of risk factors for severe viral disease in this setting may come from testing for both viruses in all donors and patients in both clinical practice and clinical trials.

Removal of inhibitors of CSF-PCR to improve diagnosis of herpesviral encephalitis.

CSF-PCR is currently the most sensitive test to diagnose encephalitis due to cytomegalovirus or herpes simplex virus. However, false negative results sometimes arise due to inhibitors in CSF. We have shown that the inhibitory effects may be due to increased levels of proteins and increased cell numbers, but are not due to cellular DNA. Simple techniques were used to remove the inhibitors and successfully apply these methods to CSF specimens that gave equivocal results when tested untreated.

HCMV-DNA is detected more frequently than infectious virus in blood leucocytes of immunocompromised patients: a direct comparison of culture-immunofluorescence and PCR for detection of HCMV in clinical specimens.

In two studies comparing detection of human cytomegalovirus (HCMV) in 118 patients (93 of whom were immunocompromised) by the polymerase chain reaction (PCR) and virus isolation using either early antigen detection by culture-immunofluorescence or conventional cytopathic effect, DNA-PCR was found to be the most sensitive, followed by culture-immunofluorescence, then by cytopathic effect. Urine was inhibitory to the action of Taq polymerase; this was overcome by concentration of HCMV with PEG 6000 prior to gene amplification. Without PEG treatment, HCMV-DNA in 6 of the 11 specimens positive by culture-immunofluorescence was not detectable by PCR. In healthy seropositive individuals, HCMV-DNA was not detected in leucocytes. However, in immunocompromised patients with AIDS or transplants, and therefore at high risk of HCMV infection or reactivation, blood leucocytes were usually positive for HCMV-DNA (19/20), some for as long as 20 weeks after initial detection and persisting for long after culture-immunofluorescence became negative. Neither HCMV-RNA nor infectious HCMV were detected in the follow-up blood leucocyte specimens from immunocompromised patients who had detectable HCMV-DNA in these cells. These data suggest that persistence of HCMV-DNA in blood leucocytes of immunocompromised patients after reactivation or primary infection may be due to persistence of non-viable virus, residual HCMV genomic DNA, or latent HCMV-DNA.

Dual antibody rises to cytomegalovirus and human herpesvirus type 6: frequency of occurrence in CMV infections and evidence for genuine reactivity to both viruses.

The frequency of high (greater than 256) IgG anti-human herpesvirus type 6 (HHV-6) titers in sera known to be positive for IgM anti-cytomegalovirus (CMV) or IgM anti-Epstein Barr virus (EBV) was significantly greater than in sera from healthy controls or from a group of ill patients who were CMV and EBV IgM-negative (15/25 and 17/25 vs. 1/25 and 2/25, respectively, P less than .001). There was serologic evidence of simultaneous HHV-6 infection or reactivation (a rise in IgG anti-HHV-6 titer or the presence of IgM anti-HHV-6) in sera from 14 of 17 primary CMV infections. In 5 of the 10 patients with concurrent rises in IgG titers to both viruses, the rise in IgG anti-HHV-6 preceded that of IgG anti-CMV. Complete removal of IgG anti-CMV reactivity from 5 sera from patients who had a primary CMV infection with a rise in IgG anti-HHV-6 titer had no effect on the IgG anti-HHV-6 titer of those sera, demonstrating that the rise in HHV-6 IgG titer was not a consequence of anti-CMV antibodies cross-reacting in the HHV-6 IgG assay.

The exanthem of Ross River virus infection: histology, location of virus antigen and nature of inflammatory infiltrate.

The exanthem of epidemic polyarthritis, a disease caused by Ross River (RR) virus, was examined three days after onset of the common erythematous and the rare purpuric forms of the eruption. The dermis showed a light perivascular infiltrate of mononuclear cells in both, with extravasation of erythrocytes in the latter. No immunoglobulins (IgM, IgG, IgA) or complement components (Clq, C3) were detected. Most of the infiltrating cells were T lymphocytes of the T suppressor-cytotoxic class. Their perivascular location, the scarcity of other lymphocytes or phagocytes, and rapid resolution of the rash indicated that the T lymphocytes were responsible for cytotoxic destruction of virus-infected cells. A few monocyte-macrophage cells were identified in the perivascular infiltrate. RR virus antigen was found in the basal epidermal and eccrine duct epithelial cells of both types of lesion and in the perivascular zone of the erythematous lesion, but appeared to have been eliminated from this region in the purpuric lesion. It is suggested that secondary effects of the T-cytotoxic reaction on nearby capillaries are responsible for erythema, oedema and purpura in the exanthem.