Kaposi's sarcoma-associated herpesvirus glycoprotein K8.1 is critical for infection in a cell-specific manner and functions at the attachment step on keratinocytes.

IMPORTANCE: Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of several B cell malignancies and Kaposi's sarcoma. We analyzed the function of K8.1, the major antigenic component of the KSHV virion in the infection of different cells. To do this, we deleted K8.1 from the viral genome. It was found that K8.1 is critical for the infection of certain epithelial cells, e.g., a skin model cell line but not for infection of many other cells. K8.1 was found to mediate attachment of the virus to cells where it plays a role in infection. In contrast, we did not find K8.1 or a related protein from a closely related monkey virus to activate fusion of the viral and cellular membranes, at least not under the conditions tested. These findings suggest that K8.1 functions in a highly cell-specific manner during KSHV entry, playing a crucial role in the attachment of KSHV to, e.g., skin epithelial cells.

Archetype JC polyomavirus DNA associated with extracellular vesicles circulates in human plasma samples.

BACKGROUND: JC polyomavirus (JCPyV) establishes a stable and successful interaction with the host, causing progressive multifocal leukoencephalopathy (PML) in immunocompromised subjects. Recently, it has been reported that JCPyV, like other viruses, may exploit extracellular vesicles (EV) in cell cultures. OBJECTIVE: To investigate the presence of JCPyV-DNA in EV circulating in human plasma obtained from patients at risk for PML. STUDY DESIGN: JCPyV-DNA status was studied in EV obtained from 170 plasma samples collected from 120 HIV positive patients and 50 healthy donors. EV were extracted from plasma and characterized by Nanoparticle tracking analysis, by western blot for presence of tetraspanin CD63, CD81, annexin II, cythocrome C protein and, finally, by immunoelectron microscopy (IEM). Presence and quantitation of JCPyV-DNA were assessed with Multiplex real-time TaqMan PCR assay. RESULTS: The JCPyV-DNA plasma prevalence in 120 HIV positive patients and 50 healthy donors was 28% and 4%, respectively. The investigation performed on well-characterized plasma EV reported JCPyV-DNA detection in 15 out of 36 (42%) of the viremic samples (14 were from HIV patients and 1 from healthy people) at a mean level of 23.5 copies/mL. The examination of EV selected samples reported the percentage of JCPyV-DNA in EV of 5.4% of the total viral load. Moreover, IEM reported the presence of JCPyV Vp1 antigen in plasma-derived EV. CONCLUSION: The potential role of EV-associated JCPyV-DNA open new avenues and mechanistic insights into the molecular strategies adopted by this polyomavirus to persist in the host and spread to the central nervous system.

Torque teno virus microRNA detection in cerebrospinal fluids of patients with neurological pathologies.

BACKGROUND: Torque teno virus (TTV) is a widespread anellovirus that establishes persistent infections in humans and represents the most abundant component of the human virome. TTV encodes microRNAs (miRNA) which are found both in viremic and not viremic subjects being potentially ideal tools for the virus to evade the immune system response and to maintain chronic infection in the host. OBJECTIVE: To investigate TTV-DNA loads and TTV-miRNAs expression in cerebrospinal fluids (CSF) from subjects under analysis for the assessment of neurological diseases. STUDY DESIGN: Detection of TTV-DNA and TTV-miRNAs (e. g. miRNA t1a, t3b, and tth8) were carried out from CSF samples of 93 subjects with neurological diseases by using universal real-time PCR, real-time RT-PCR, and next-generation sequencing (NGS) analyses. RESULTS: TTV-DNA was detected in 11 of 93 (12 %) CSFs with a mean TTV load of 155 copies/mL. Conversely, 29 CSF samples (31 %) were positive for at least one TTV-miRNA, while 15 (16 %) CSFs contained all the TTV-miRNAs examined. Overall, TTV-miRNA tth8 was detected in 62 % of samples, followed by TTV miRNA t3b (56 %), and t1a (29 %). Interestingly, TTV-miRNAs were found in CSF samples that were negative for the presence of TTV-DNA. Next-generation sequencing analysis carried out from 4 TTV-DNA negative CSF samples detected reads mapped in TTV-miRNA sequences region. CONCLUSIONS: These results shed novel light on the relationship between TTV and the central nervous system and make compelling furthered studies for investigating the potential role of TTV-miRNAs in neurological disorders.