Taishi Tanabe

Dual-subtype FIV vaccine protects cats against in vivo swarms of both homologous and heterologous subtype FIV isolates

ObjectiveTo evaluate the immunogenicity and efficacy of an inactivated dual-subtype feline immunodeficiency virus (FIV) vaccine. DesignSpecific-pathogen-free cats were immunized with dual-subtype (subtype A FIVPet and subtype D FIVShi) vaccine and challenged with either in vivo- or in vitro-derived FIV inocula. MethodsDual-subtype vaccinated, single-subtype vaccinated, and placebo-immunized cats were challenged with in vivo-derived heterologous subtype B FIVBang [10–100 50% cat infectious doses (CID50)], in vivo-derived homologous FIVShi(50 CID50), and in vitro- and in vivo-derived homologous FIVPet(20–50 CID50). Dual-subtype vaccine immunogenicity and efficacy were evaluated and compared to single-subtype strain vaccines. FIV infection was determined using virus isolation and proviral PCR of peripheral blood mononuclear cells and lymphoid tissues. ResultsFour out of five dual-subtype vaccinated cats were protected against low-dose FIVBang (10 CID50) and subsequently against in vivo-derived FIVPet (50 CID50) challenge, whereas all placebo-immunized cats became infected. Furthermore, dual-subtype vaccine protected two out of five cats against high-dose FIVBang challenge (100 CID50) which infected seven out of eight single-subtype vaccinated cats. All dual-subtype vaccinated cats were protected against in vivo-derived FIVPet, but only one out of five single-subtype vaccinated cats were protected against in vivo-derived FIVPet. Dual-subtype vaccination induced broad-spectrum virus-neutralizing antibodies and FIV-specific interferon-γ responses along with elevated FIV-specific perforin mRNA levels, suggesting an increase in cytotoxic cell activities. ConclusionDual-subtype vaccinated cats developed broad-spectrum humoral and cellular immunity which protected cats against in vivo-derived inocula of homologous and heterologous FIV subtypes. Thus, multi-subtype antigen vaccines may be an effective strategy against AIDS viruses.

IFNγ inhibition of cell growth in glioblastomas correlates with increased levels of the cyclin dependent kinase inhibitor p21 WAF1/CIP1

Glioblastoma is a highly aggressive form of brain cancer characterized by uncontrolled cell growth resulting from a loss of cell cycle regulation. In this study we determined the antiproliferative effects of interferon gamma (IFNγ) on the glioblastoma cell lines T98G, SNB-19 and U-373, focusing on the ability of IFNγ to increase levels of p21WAF1/CIP1, an important negative regulator of cell cycle events. IFNγ was found to inhibit the growth of all cell lines, with inhibition ranging from 82.2% to 45.4%. Flow cytometry analysis showed that IFNγ treatment caused a cell cycle delay in the G1 or S phases. The strength of this delay varied, correlating with the degree by which IFNγ inhibited proliferation of each cell line. IFNγ treatment increased the production of the cyclin dependent kinase inhibitor (CKI) p21WAF1/CIP1 in all cell lines, the level and kinetics of production of which correlated with the degree and stage of inhibition of cellular proliferation. Further, immunoprecipitation of p21WAF1/CIP1 in complexes of p21WAF1/CIP1/cyclin-dependent kinase 2 (cdk2)/cyclin showed that the amount of p21WAF1/CIP1 in the complexes and the inhibition of cdk2-cyclin kinase activity correlated with the level of p21WAF1/CIP1 produced in the cells by IFNγ. These results show that IFNγ has significant antiproliferative effects on the glioblastoma cell lines and suggest that p21WAF1/CIP1 plays a role in mediating these effects.

Dual-subtype FIV vaccine (Fel-O-Vax® FIV) protection against a heterologous subtype B FIV isolate

Vaccine trials were undertaken to determine whether the Fel-O-Vax® FIV, a commercial dual-subtype (subtypes A and D) feline immunodeficiency virus (FIV) vaccine, is effective against a subtype B FIV isolate. Current results demonstrate the Fel-O-Vax FIV to be effective against a subtype B virus, a subtype reported to be the most common in the USA.

Inhibition of the glioblastoma cell cycle by type I IFNs occurs at both the G1 and S phases and correlates with the upregulation of p21WAF1/CIP1

The antiproliferative effect of IFNα was tested on the human glioblastoma cell lines, U-373MG and T98G. IFNα significantly inhibited the growth of both cell lines, but was more effective in retarding the growth of U-373MG cells. Flow cytometry analysis indicated that synchronized IFNα-treated U-373MG cells showed a strong block in the progression of cells out of the S phase of the cell cycle. T98G cells, on the other hand, showed a moderate delay in the transition of cells from G1 to S phase and only a slight delay in the S phase, consistent with the decreased antiproliferative effect of IFNα on this cell line. IFNα-treated cells were then tested for the induction of the tumor suppressor gene product, p21WAF1/CIP1. Higher levels of p21WAF1/CIP1 were detected in lysates from IFNα-treated U-373MG cells as compared to media controls for as long as 18 h. In IFNα-treated T98G cells, p21WAF1/CIP1 levels were slightly elevated at 4 and 6 h, but decreased to levels similar to controls thereafter, correlating with the antiproliferative effects of IFNα on each cell line. Immunoprecipitation studies on lysates from IFNα-treated U-373MG and T98G cells indicated that increased amounts of p21WAF1/CIP1 were complexed to both cyclin D1 and cyclin E. Further, reduced cyclin-dependent kinase 2 (cdk2) activity was found in both IFNα-treated U-373MG and T98G cells, suggesting a mechanism by which p21WAF1/CIP1 exerted its antiproliferative effects. Lastly, we analyzed the time-dependent production of the cyclins Dl, E, and A. No differences in cyclin D1 levels were found between IFNα-treated and media-treated U-373MG and T98G cells. However, both IFNα-treated U-373MG and T98G cells showed a prolonged elevation in cyclin E, correlating with the G1 to S phase delays observed in these cell lines. Further, the duration of cyclin E production corresponded with the magnitude of the cell cycle delays seen in IFNα-treated U-373MG and T98G cells. Prolonged elevation of cyclin A was also seen in both IFNα-treated U-373MG and T98G cells, the magnitude of which correlated with the S phase delay observed in these cell lines. Thus, the data indicate that IFNα has significant antiproliferative activity against glioblastoma cells that is mediated, at least in part, by the tumor suppressor gene product, p21WAF1/CIP1.

Feline Immunodeficiency Virus Lacks Sensitivity to the Antiviral Activity of Feline IFN-γ

The antiviral activity of recombinant feline interferon-γ (rFeIFN-γ) against feline immunodeficiency virus (FIV) was investigated. A persistently FIVBang-infected feline T cell line (FeT-J/Bang) wa...