Naturally occurring genotype 2b/1a hepatitis C virus in the United States

<p>Abstract</p> <p>Background</p> <p>Hepatitis C Virus (HCV) infected patients are frequently repeatedly exposed to the virus, but very few recombinants between two genotypes have been reported.</p> <p>Findings</p> <p>We describe the discovery of an HCV recombinant using a method developed in a United States clinical lab for HCV genotyping that employs sequencing of both 5' and 3' portions of the HCV genome. Over twelve months, 133 consecutive isolates were analyzed, and a virus from one patient was found with discordant 5' and 3' sequences suggesting it was a genotype 2b/1a recombinant. We ruled out a mixed infection and mapped a recombination point near the NS2/3 cleavage site.</p> <p>Conclusions</p> <p>This unique HCV recombinant virus described shares some features with other recombinant viruses although it is the only reported recombinant of a genotype 2 with a subtype 1a. This recombinant represents a conundrum for current clinical treatment guidelines, including treatment with protease inhibitors. This recombinant is also challenging to detect by the most commonly employed methods of genotyping that are directed primarily at the 5' structural portion of the HCV genome.</p

A role for ubiquitin ligase recruitment in retrovirus release

Retroviral Gag polyproteins have specific regions, commonly referred to as late assembly (L) domains, which are required for the efficient separation of assembled virions from the host cell. The L domain of HIV-1 is in the C-terminal p6(gag) domain and contains an essential P(T/S)AP core motif that is widely conserved among lentiviruses. In contrast, the L domains of oncoretroviruses such as Rous sarcoma virus (RSV) have a more N-terminal location and a PPxY core motif. In the present study, we used chimeric Gag constructs to probe for L domain activity, and observed that the unrelated L domains of RSV and HIV-1 both induced the appearance of Gag-ubiquitin conjugates in virus-like particles (VLP). Furthermore, a single-amino acid substitution that abolished the activity of the RSV L domain in VLP release also abrogated its ability to induce Gag ubiquitination. Particularly robust Gag ubiquitination and enhancement of VLP release were observed in the presence of the candidate L domain of Ebola virus, which contains overlapping P(T/S)AP and PPxY motifs. The release defect of a minimal Gag construct could also be corrected through the attachment of a peptide that serves as a physiological docking site for the ubiquitin ligase Nedd4. Furthermore, VLP formation by a full-length Gag polyprotein was sensitive to lactacystin, which depletes the levels of free ubiquitin through inhibition of the proteasome. Our findings suggest that the engagement of the ubiquitin conjugation machinery by L domains plays a crucial role in the release of a diverse group of enveloped viruses

An atypical case of Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC)-associated renal cell carcinoma identified by next-generation sequencing

Germline mutations in the fumarate hydratase (FH) gene classically lead to Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC) syndrome. Patients with HLRCC typically exhibit multiple cutaneous and uterine leiomyomas at a young age. They also display a 20–30% lifetime risk for renal carcinomas, which commonly present before 40 years of age, have a distinct papillary morphology, and an aggressive phenotype. However, the clinical presentation of HLRCC and the morphology of HLRCC-associated renal cell carcinomas (RCCs) can be variable and thereby evade diagnosis. Here, we present two cases of HLRCC-associated RCC to emphasize this point. The first case is typical of HLRCC, involving a 29-year-old man with multiple cutaneous leiomyomas and a renal tumor with characteristic papillary morphology. Next, we describe a 48-year-old man presenting with metastatic cancer of unknown primary origin and no skin findings. Interestingly, next-generation sequencing of his metastatic tumor identified two unique FH mutations. In both cases, FH mutations were confirmed as germline. These cases highlight the variable presentations of HLRCC-associated RCC and underscore the importance of screening tumors of unknown origin for FH mutations using next-generation sequencing. Keywords: Renal cell carcinoma, HLRCC, Fumarate hydratase, Next-generation sequencin