Mucosal immunization against hepatitis A: antibody responses are enhanced by co-administration of synthetic oligodeoxynucleotides and a novel cationic lipid.

Hepatitis A caused by hepatitis A virus (HAV) transmitted by the fecal-oral route, results in considerable morbidity and economic loss. Mucosal immunization can be more effective than conventional injection at inducing both local and systemic immunity to HAV. Here we show that co-administration of killed HAV with synthetic oligodeoxynucleotides (ODNs) containing CpG sequences, and a novel polycationic sphingolipid (CCS)/cholesterol liposomal delivery system, markedly enhances the HAV-specific antibody response at the intestinal interface, particularly when delivered intrarectally or intranasally, to Balb/c mice at low HAV doses. A mucosally delivered, antigen-sparing HAV vaccine that is easily administered without specialized equipment or personnel, is an attractive alternative for facilitating mass immunization in hepatitis A outbreaks.

Multiple adaptive mechanisms to chronic liver disease revealed at early stages of liver carcinogenesis in the Mdr2-knockout mice.

Molecular events preceding the development of hepatocellular carcinoma were studied in the Mdr2-knockout (Mdr2-KO) mice. These mice lack the liver-specific P-glycoprotein responsible for phosphatidylcholine transport across the canalicular membrane. Portal inflammation ensues at an early age followed by hepatocellular carcinoma development after the age of 1 year. Liver tissue samples of Mdr2-KO mice in the early and late precancerous stages of liver disease were subjected to histologic, biochemical, and gene expression profiling analysis. In an early stage, multiple protective mechanisms were found, including induction of many anti-inflammatory and antioxidant genes and increase of total antioxidant capacity of liver tissue. Despite stimulation of hepatocyte DNA replication, their mitotic activity was blocked at this stage. In the late stage of the disease, although the total antioxidant capacity of liver tissue of Mdr2-KO mice was normal, and inflammation was less prominent, many protective genes remained overexpressed. Increased mitotic activity of hepatocytes resulted in multiple dysplastic nodules, some of them being steatotic. Expression of many genes regulating lipid and phospholipid metabolism was distorted, including up-regulation of choline kinase A, a known oncogene. Many other oncogenes, including cyclin D1, Jun, and some Ras homologues, were up-regulated in Mdr2-KO mice at both stages of liver disease. However, we found no increase of Ras activation. Our data suggest that some of the adaptive mechanisms induced in the early stages of hepatic disease, which protect the liver from injury, could have an effect in hepatocarcinogenesis at later stages of the disease in this hepatocellular carcinoma model.

Rectal immunization of mice with hepatitis A vaccine induces stronger systemic and local immune responses than parenteral immunization.

Systemic (spleen cell (SPLC), serum antibodies) and intestinal mucosal (Peyer's patch cells (PPC), lamina propria lymphocytes (LPLs), coproantibodies) immune responses were compared in mice immunized with varying doses (144, 72, 36, 18 ELISA units [EU]) of HAVRIX, an alum-adsorbed killed hepatitis A virus (HAV) vaccine, delivered either intrarectally (i.r.) or intraperitoneally (i.p.) in three doses at weekly intervals. HAV-specific IgG, IgM, and IgA antibody responses were evaluated by ELISPOT and EIA and HAV-responsive lymphocytes by lymphocyte stimulation assays. Systemic IgG responses were greater in mice immunized intraperitoneally with 144, 72, and 36EU of HAVRIX, while IgM and IgA responses were greater in PPC and LPL cell populations, serum and coproantibodies of rectally immunized mice, particularly at HAVRIX doses of 36 and 18EU. Rectal immunization at lower doses (36, 18EU) also elicited strong cellular responses in all cell populations while parenteral (i.p.) vaccination, did not. Results suggest that rectal immunization may be a highly effective way of inducing both local and systemic immunity to HAV.

Parvovirus B19 nonstructural (NS1) protein as a transactivator of interleukin-6 synthesis: common pathway in inflammatory sequelae of human parvovirus infections?

This review focuses on the role that human parvovirus B19 nonstructural (NS1) protein as a transactivator of the proinflammatory cytokine, interleukin-6 (IL-6), might play in triggering the multiparametric inflammatory outcomes of B19 infection. Parvovirus B19 is a ubiquitous virus, and it is often expressed during conditions of immunodepression including that induced by long-term chemotherapy, viral infection (HIV, HTLV-1), or genetic immunodeficiency disorders. Through NS1 expression, B19 may contribute to the immune dysregulation associated with these disorders, or serve as a cofactor in enhancing retroviral replication. Hence, NS1 transactivation of proinflammatory cytokine promoters such as IL-6 may be pivotal in triggering the various inflammatory and autoimmune disorders that have been linked to parvovirus B19 infections.

Lymphocyte recognition of human parvovirus B19 non-structural (NS1) protein: associations with occurrence of acute and chronic arthropathy?

Immune recognition of recombinant parvovirus B19 non-structural (rNS1) protein was studied by immunoblot and lymphoproliferative assays in blood from the following B19 seropositive groups: B19 infected (n = 14), B19 exposed but non-infected (n = 16), other illness with rash (n = 3), chronic arthropathy of unknown aetiology (n = 4) and healthy controls (n = 7). Sera from 11 B19 seronegative subjects were also studied. Sera collected at initial diagnosis or at the time of accidental B19 exposure in pregnancy were tested for NS1 antibody and evidence of B19 DNA by nested PCR. Follow-up specimens were obtained 3-12 months later for serological, PCR and proliferation studies. B19 DNA was detected sporadically in early specimens and in one follow-up specimen from a subject who developed chronic arthropathy after B19 infection. There was no correlation with development of arthropathy. NS1-specific IgG was detected in early sera from B19-infected and exposed subjects but to a lesser degree in follow-up specimens, and in only one healthy control serum. No correlation with the presence of NS1-specific antibodies was found with development of acute or chronic arthropathy. Although lymphocyte proliferation in response to stimulation with rNS1 in vitro occurred at a higher frequency in patients who developed acute and chronic joint manifestations after B19 infection, suggesting an association with this outcome, NS1-reactive lymphocytes were also found in three B19 seronegative patients, two of whom had recently been exposed to B19 but had no illness. Hence, immune recognition of NS1 may be more indicative of recent infection with, or exposure to, parvovirus B19 than associated with development of arthropathy as previously reported.