Herpes Simplex Virus Type 2 UL24 Gene Is a Virulence Determinant in Murine and Guinea Pig Disease Models

A herpes simplex virus type 2 (HSV-2) UL24 β-glucuronidase (UL24-βgluc) insertion mutant was derived from HSV-2 strain 186 via standard marker transfer techniques. Cell monolayers infected with UL24-βgluc yielded cytopathic effect with syncytium formation. UL24-βgluc replicated to wild-type viral titers in three different cell lines. UL24-βgluc was not virulent after intravaginal inoculation of BALB/c mice in that all inoculated animals survived doses up to 400 times the 50% lethal dose (LD(50)) of the parental virus. Furthermore, few UL24-βgluc-inoculated mice developed any vaginal lesions. Intravaginal inoculation of guinea pigs with UL24-βgluc at a dose equivalent to the LD(50) of parental virus (≈5 × 10(3) PFU) was not lethal (10/10 animals survived). Although genital lesions developed in some UL24-βgluc-inoculated guinea pigs, both the overall number of lesions and the severity of disease were far less than that observed for animals infected with parental strain 186

Recombinant Vesicular Stomatitis Virus Vectors Expressing Herpes Simplex Virus Type 2 gD Elicit Robust CD4(+) Th1 Immune Responses and Are Protective in Mouse and Guinea Pig Models of Vaginal Challenge

Recombinant vesicular stomatitis virus (rVSV) vectors offer an attractive approach for the induction of robust cellular and humoral immune responses directed against human pathogen target antigens. We evaluated rVSV vectors expressing full-length glycoprotein D (gD) from herpes simplex virus type 2 (HSV-2) in mice and guinea pigs for immunogenicity and protective efficacy against genital challenge with wild-type HSV-2. Robust Th1-polarized anti-gD immune responses were demonstrated in the murine model as measured by induction of gD-specific cytotoxic T lymphocytes and increased gamma interferon expression. The isotype makeup of the serum anti-gD immunoglobulin G (IgG) response was consistent with the presence of a Th1-CD4(+) anti-gD response, characterized by a high IgG2a/IgG1 IgG subclass ratio. Functional anti-HSV-2 neutralizing serum antibody responses were readily demonstrated in both guinea pigs and mice that had been immunized with rVSV-gD vaccines. Furthermore, guinea pigs and mice were prophylactically protected from genital challenge with high doses of wild-type HSV-2. In addition, guinea pigs were highly protected against the establishment of latent infection as evidenced by low or absent HSV-2 genome copies in dorsal root ganglia after virus challenge. In summary, rVSV-gD vectors were successfully used to elicit potent anti-gD Th1-like cellular and humoral immune responses that were protective against HSV-2 disease in guinea pigs and mice

De novo missense variants in phosphatidylinositol kinase PIP5KIγ underlie a neurodevelopmental syndrome associated with altered phosphoinositide signaling

Phosphoinositides (PIs) are membrane phospholipids produced through the local activity of PI kinases and phosphatases that selectively add or remove phosphate groups from the inositol head group. PIs control membrane composition and play key roles in many cellular processes including actin dynamics, endosomal trafficking, autophagy, and nuclear functions. Mutations in phosphatidylinositol 4,5 bisphosphate [PI(4,5)P2] phosphatases cause a broad spectrum of neurodevelopmental disorders such as Lowe and Joubert syndromes and congenital muscular dystrophy with cataracts and intellectual disability, which are thus associated with increased levels of PI(4,5)P2. Here, we describe a neurodevelopmental disorder associated with an increase in the production of PI(4,5)P2 and with PI-signaling dysfunction. We identified three de novo heterozygous missense variants in PIP5K1C, which encodes an isoform of the phosphatidylinositol 4-phosphate 5-kinase (PIP5KIγ), in nine unrelated children exhibiting intellectual disability, developmental delay, acquired microcephaly, seizures, visual abnormalities, and dysmorphic features. We provide evidence that the PIP5K1C variants result in an increase of the endosomal PI(4,5)P2 pool, giving rise to ectopic recruitment of filamentous actin at early endosomes (EEs) that in turn causes dysfunction in EE trafficking. In addition, we generated an in vivo zebrafish model that recapitulates the disorder we describe with developmental defects affecting the forebrain, including the eyes, as well as craniofacial abnormalities, further demonstrating the pathogenic effect of the PIP5K1C variants. We describe a neurodevelopmental disorder associated with de novo gain-of-function variants in PIP5KIγ kinase. The variants cause perturbed endosomal function resulting from increased production of phosphatidylinositol 4,5 bisphosphate and enhanced association of F-actin at endosomes. Moreover, mutant zebrafish larvae recapitulate the phenotypes observed in affected individuals from our cohort