Molecular characteristics of occult hepatitis B virus from blood donors in southeast China.

The characteristics of 30 carriers with occult hepatitis B virus (HBV) infection (OBI) were compared with those of 30 individuals diagnosed as being HBV carriers at the time of blood donation, 60 asymptomatic carriers, and 60 chronic hepatitis patients. The prevalence of genotype C was significantly higher in carriers with OBIs than in any other HBsAg-positive (HBsAg(+)) group (P < 0.001). Specific amino acid substitutions in the regions from amino acids 117 to 121 and amino acids 144 to 147 located in the major hydrophilic region of the S gene were associated with carriers with OBIs (P < 0.01 for carriers with OBIs versus HBsAg(+) donors, carriers with OBIs versus HBsAg(+) asymptomatic carriers, and carriers with OBIs versus HBsAg(+) chronic hepatitis patients). G145R was the major variation in the HBV isolates responsible for local occult HBV infections.

Mycoplasma hominis lipid-associated membrane protein antigens for effective detection of M. hominis-specific antibodies in humans.

Lipid-associated membrane proteins (LAMPs) from 14 Mycoplasma hominis isolates or strains share similar protein and antigenicity profiles. Of 31 human immunodeficiency virus-infected patients from whose samples M. hominis was cultured, 28 tested strongly positive for serum antibodies to M. hominis LAMPs. The remaining 3 serum samples showed low antibody titer to LAMPs from all of the 14 M. hominis isolates or strains, which was likely the result of the compromised immune systems of the patients. Thus, M. hominis LAMPs as a whole are homogenous in antigenicity within the species, despite having many different serotypes. Serological study involving 564 healthy blood donors and 211 patients attending sexually transmitted disease clinics by LAMPs showed that general populations were widely exposed to M. hominis. Women were infected with M. hominis at a younger age than were men. The prevalence of infection increased markedly among sexually active persons.

Hepatitis e vaccine to prevent morbidity and mortality during epidemics.

Recurrent, large, waterborne epidemics of hepatitis E virus (HEV) occur regularly after monsoon rains contaminate water supplies in Asia or during humanitarian crises in Africa. These epidemics commonly affect thousands of persons, and it has a high mortality in pregnant women who become infected. Although a subunit HEV vaccine has been developed by Chinese investigators and was found to be highly effective and safe in a large clinical trial, this vaccine is only available in China. Until it is prequalified by the World Health Organization, the vaccine may not be available for use outside of China in low-income countries that lack national vaccine regulatory agencies. In this manuscript, we explore possible strategies for providing access to this potentially important vaccine for international use in responding to epidemics of HEV in low-resource countries.

The modulation of hepatitis C virus 1a replication by PKR is dependent on NF-kB mediated interferon beta response in Huh7.5.1 cells.

Protein kinase R (PKR), a sensor of double-stranded RNA, plays an important role in the host response to viral infection. Hepatitis C genotype 2a virus (HCV2a) has been shown to induce PKR activation to suppress the translation of antiviral interferon stimulated genes (ISGs), suggesting that PKR inhibitor can be beneficial for treating chronically HCV-infected patients in conjunction with interferon alpha and ribavirin. However, in this study, we found that PKR inhibition using siRNA PKR, shRNA PKR or PKR inhibitor enhanced HCV 1a replication and rendered Huh7.5.1 cells more susceptible to HCV1a infection. Additionally, PKR silencing suppressed NF-kB activation and NF-kB mediated STAT1 phosphorylation in Huh7.5.1 cells and HCV1a persistently infected Huh7.5.1 cells (2HDD4). These effects were accompanied by a reduction of interferon beta response and thereby enhanced HCV1a replication in Huh7.5.1 cells. We conclude that host cells can employ PKR activation to restrict HCV1a replication through regulation of NF-kB expression.

The enhancement of RNAi against HIV in vitro and in vivo using H-2K(k) protein as a sorting method.

Gene therapy offers a potentially an effective treatment for many human diseases, including HIV/AIDS. One of the most studied gene delivery systems is the use of lentivirus based vectors, which can deliver genes into both dividing and nondividing cells. However, low infection efficiency represents an obstacle for proper evaluation of their biological function. In this study, a recombinant lentiviral vector which expressed short hairpin RNAs (shRNAs) targeted against the HIV-1 vif/pol was transduced into various cells. An MHC class I molecule, H-2K(k), was used as a marker to accumulate the virally transduced cells through immunomagnetic sorting. In vitro testing of transduced cells showed 85% suppression of HIV in post-sorted PBMCs compared to 30% in pre-sorted PBMCs. In additional, using a mouse xenotransplantation model with the same treatment protocol for cell enrichment, a >95% decrease in HIV activity in post-sorted cells was achieved, as compared to nearly none in the pre-sorted cells. These studies offer a practical method to accumulate virally transduced cells, which can be applied to evaluate the performance of various shRNAs constructs.

Mycoplasma fermentans infection promotes immortalization of human peripheral blood mononuclear cells in culture.

Chronic infection or colonization by mycoplasma(s) could gradually and significantly alter many biologic properties of mammalian host cells in culture, including induction of malignant transformation. We examined effects of Mycoplasma fermentans infection on the continuing survival and immortality of human peripheral blood mononuclear cells (PBMCs) from healthy blood donors. Without specific supplemental growth factors, human PBMCs normally die rapidly, with few cells other than macrophages/monocytes surviving after 2 weeks in cultures. Only occasional Epstein-Barr virus (EBV)-positive B lymphocytes would continue to proliferate and undergo spontaneous immortalization. Our present study revealed that infection of human PBMCs in culture with the incognitus and PG18 strains of M fermentans, but surprisingly not with some other strains tested in parallel, markedly enhanced the rate of EBV-positive B lymphocytes to undergo immortalization (74% vs 17%). Compared with spontaneously immortalized PBMCs, the PBMCs immortalized in cultures infected with the mycoplasmas often had prominent karyotype changes with chromosomal loss, gain, or translocations. Furthermore, many of these immortalized B lymphocytes were found to be monoclonal in nature. The in vitro findings would be of relevance to lymphoproliferative disorders that occurred in patients with immune suppression. The mycoplasma-mediated promotional effect in cell immortalization and its potential clinical implications warrant further study.