West-Nile virus encephalitis in an immunocompetent pediatric patient: successful recovery

Background

West Nile virus (WNV) is a mosquito-borne RNA virus belonging to the Flaviviridae family. Symptomatic infection happens in only about 20% of the cases, while WNV neuroinvasive disease (WNND) is rare and accounts for less than 1%. There is insufficient information about natural history and clinical course in children, because underdiagnosis is common, and reports are scarce. On the other hand, Europe has seen a dramatic increase of WNV infections in the last decades, and the Po valley itself, in Northern Italy, has become an endemic region since 2013.

Case presentation

We hereby report a case of West-Nile virus neuroinvasive disease in a 12-year-old boy. This is one of the very few cases diagnosed in the Italian pediatric population. The clinical presentation was compatible with acute encephalitis. Diagnosis was made by detection of specific IgM in both serum and cerebrospinal fluid. He finally was discharged with complete recovery, and no neurologic sequelae after a 12-months follow up period.

Conclusions

Given its non-specific clinical presentation, the diffusion of WNV constitutes a crucial and emerging concern. Even though rare, neuroinvasive WNV infection should always be suspected in pediatric patients, living or traveling in endemic areas, presenting with meningitis, encephalitis or acute flaccid paralysis during the WNV transmission season.

     

Early virus isolation, early structural antigen detection and DNA amplification by the polymerase chain reaction in polymorphonuclear leukocytes from AIDS patients with human cytomegalovirus viraemia.

Fifty AIDS patients were investigated for human cytomegalovirus (HCMV) viraemia when potentially HCMV-related clinical symptoms or syndromes were observed. Nine patients underwent prolonged virologic follow-up, while 41 additional patients were examined only once or sporadically. Concentrated preparations of polymorphonuclear leukocytes (PMNL) from 153 blood samples were obtained for monitoring: (1) early virus isolation in cell cultures 24 h p.i. (viraemia); (2) early structural antigen detection in cytospin preparations (antigenemia); and (3) HCMV DNA in blood (DNAemia) through DNA amplification by the polymerase chain reaction (PCR). Viraemia and antigenemia were quantitated, whereas evaluation of DNAemia was only qualitative. A good correlation between levels of viraemia and antigenemia was consistently found except during ganciclovir treatment. HCMV-related clinical symptoms were observed when the number of infected PMNL was greater than 100 per 2 x 10(5) cells examined. All 56 blood samples positive for viraemia and antigenemia were also PCR-positive, whereas 44 samples (39 of which taken from patients with ascertained HCMV infection in blood) were positive by PCR only. Viraemia and antigenemia were often unrelated to HCMV organ syndromes, such as retinitis, in which only DNAemia was often detected. Prolonged ganciclovir treatment kept viraemia, antigenemia and even DNAemia at a low or negative level, yet drug discontinuation led to rapid progression of HCMV infection in blood. In addition, prolonged antiviral treatment could induce appearance of ganciclovir-resistant HCMV strains, requiring alternative foscarnet therapy. In conclusion, determination of viraemia and antigenemia appears essential for correct clinical management and antiviral treatment of disseminated HCMV infections in AIDS patients. However, PCR is the most sensitive method for diagnosis and monitoring of HCMV infections in blood at a pre-clinical stage.     

Genomes of the endothelial cell-tropic variant and the parental Toledo strain of human cytomegalovirus are highly divergent

The low-passage Toledo strain of human cytomegalovirus (HCMV) and fresh clinical HCMV isolates have been reported to share the capacity to propagate efficiently in endothelial cell cultures. In the laboratory, however, repeated attempts to adapt the Toledo strain to growth in endothelial cells have been unsuccessful. Southern blot analysis of the entire viral genome and restriction length polymorphism analysis of multiple genome regions amplified by PCR demonstrated that the reported endothelial cell-tropic viral variant of the Toledo strain and the parental Toledo strain are highly divergent. In fact, the restriction profile of the genome of the endothelial cell-tropic variant seems highly distinct from that of the parental strain. In conclusion, the degree of dissimilarity between the two genomes suggests that the endothelial cell-tropic variant of the Toledo strain could have originated from a recombination event.     

Serum antibody response to the gH/gL/pUL128–131 five-protein complex of human cytomegalovirus (HCMV) in primary and reactivated HCMV infections

Background

Recently, a new human cytomegalovirus (HCMV) glycoprotein complex has been identified and potentially proposed as a vaccine.

Objective

The aim of this study was to determine whether the HCMV gH/gL/pUL128–pUL130–pUL131 (gH/gL/pUL128–131) 5-protein (pentameric) complex (which has been recently found to be indispensable for the infection of endothelial and epithelial cells) is able to elicit a consistent antibody response in both primary and reactivated HCMV infections.

Study design

The antibody response was determined by both indirect immunofluorescence (IFA) and ELISA, using fixed (IFA) or lysed (ELISA) epithelial (ARPE-19) cells infected with one or more adenoviral vectors, each carrying one HCMV gene and, in parallel, with a control adenovirus vector.

Results

The specificity of results was determined by the reactivity of human neutralizing mAbs recognizing two, three, or four proteins of the complex. In 14 cases of primary infection, an IgG antibody seroconversion to the UL128–131 gene products was consistently detected within 2–4 weeks after onset of infection, while antibodies persisted for at least 12 months. The IgG antibody response to UL128–131 gene products was generally superior to the response to gH and appeared to follow the neutralizing antibody response (as determined in epithelial cells). In reactivated infections, the antibody response showed a trend reminiscent of a booster response. IgG antibodies were detected in HCMV-seropositive healthy adult controls, but not in HCMV-seronegative individuals.

Conclusions

The IgG antibody response to the pentameric complex could be a major target for the evaluation of the antibody response to a pentamer-based vaccine.     

Positive HCMV DNAemia in stem cell recipients undergoing letermovir prophylaxis is expression of abortive infection

Letermovir (LMV) inhibits HCMV replication by binding to components of the HCMV-terminase complex showing a potential role in prevention of HCMV-related complications in allogenic hematopoietic stem cell transplant recipients (allo-HSCTRs). However, little is known about breakthrough HCMV infection and the relevance of HCMV DNAemia during prophylaxis. We reported the results of a multicenter prospective study involving five Italian centers in the management of HCMV DNAemia in 75 adult HCMV-seropositive allo-HSCTRs undergoing LMV prophylaxis. The aim of the present study was to characterize the presence of real HCMV reactivation during LMV prophylaxis. Then, the presence of circulating infectious HCMV particles was determined by virus isolation and degradation of free-floating viral DNA. This report provides the first evidence that during LMV prophylaxis the clinical relevance of HCMV DNAemia should be critically considered.     

Monitoring of human cytomegalovirus infections and ganciclovir treatment in heart transplant recipients by determination of viremia, antigenemia, and DNAemia.

Fourteen heart transplant recipients were monitored for human cytomegalovirus (HCMV) infection based on determination of antigenemia, viremia, and DNAemia (by polymerase chain reaction [PCR]) in peripheral blood polymorphonuclear leukocytes (PMNL). Three patients had symptomatic primary, 10 had recurrent (3 asymptomatic), and 1 (seronegative) had no HCMV infection. Severe clinical symptoms appeared when levels of viremia/antigenemia were greater than 50 infected PMNL/2 x 10(5) cells examined. Of 200 blood samples examined, 93 (46.5%) were positive for viremia/antigenemia and DNAemia, whereas 48 (24.0%) were positive for DNAemia only; 59 (29.5%) were negative in all assays. Follow-up of HCMV infections in heart transplant recipients showed that PCR can detect viral appearance in blood 7-10 days earlier than assays for antigenemia/viremia. On the other hand, viral disappearance from blood, as assessed by PCR, occurred weeks or months later than revealed by other assays. Detection of virus by PCR only was never associated with overt HCMV-related clinical symptoms. Of the 8 symptomatic patients treated with ganiclovir, 2 became PCR-negative at the end of treatment and 1 cleared virus from blood in the following weeks, whereas 5 showed persistent or recurrent infection.