Discovery and validation of potential bacterial biomarkers for lung cancer.

Microbes are residents in a number of body sites, including the oral and nasal cavities, which are connected to the lung via the pharynx. The associations between oral diseases and increased risk of lung cancer have been reported in previous prospective studies. In this study, we measured variations of salivary microbiota and evaluated their potential association with lung cancer, including squamous cell carcinoma (SCC) and adenocarcinoma (AC). A three-phase study was performed: First, we investigated the salivary microbiota from 20 lung cancer patients (10 SCC and 10 AC) and control subjects (n=10) using a deep sequencing analysis. Salivary Capnocytophaga, Selenomonas, Veillonella and Neisseria were found to be significantly altered in patients with SCC and AC when compared to that in control subjects. Second, we confirmed the significant changes of Capnocytophaga, Veillonella and Neisseria in the same lung cancer patients using quantitative PCR (qPCR). Finally, these bacterial species were further validated on new patient/control cohorts (n=56) with qPCR. The combination of two bacterial biomarkers, Capnocytophaga and Veillonella, yielded a receiver operating characteristic (ROC) value of 0.86 with an 84.6% sensitivity and 86.7% specificity in distinguishing patients with SCC from control subjects and a ROC value of 0.80 with a 78.6% sensitivity and 80.0% specificity in distinguishing patients with AC from control subjects. In conclusion, we have for the first time demonstrated the association of saliva microbiota with lung cancer. Particularly, the combination of the 16S sequencing discovery with qPCR validation studies revealed that the levels of Capnocytophaga and Veillonella were significantly higher in the saliva from lung cancer patients, which may serve as potential biomarkers for the disease detection/classification.

Involvement of non-structural proteins (NS) in influenza A infection and viral tropism.

Hemagglutinin (HA) of influenza A has been reported as the key protein in viral infection. Therefore, the density and the dynamic pattern of this protein in viral envelope will affect the virus to infect target cells. We used a lentiviral system to study the influenza A H1N1 viral infection. Herein we demonstrate that the influenza non-structural proteins (NS) significantly promote viral infection. By substituting NS gene segment from an H1N1 genome set of A/WSN/1933 with the NS segment isolated from another H1N1 substrain genome set, China246, we found that viral infection tropism was significantly altered. The reassortant H1N1 shows almost identical infectivity compared with its parental virus, A/WSN/1933, for the human epithelial cell line HOT, but shows only 1/100 infectivity of its parental virus when infecting the Madin-Darby canine kidney (MDCK) cell line. These results suggest that not only is NS important in the infectivity of human influenza virus, but that it may play a critical role in viral tropism, allowing the virus to mutate and spread to other species.

gp120-independent HIV infection of cells derived from the female reproductive tract, brain, and colon.

The infection of CD4 cells may have significant involvement in the transmission and long-term persistency of HIV. Using HIV clones carrying the enhanced green fluorescent protein (EGFP), we infected epithelial and glioneuronal cell lines derived from the female reproductive tract, brain, colon, and intestine. HIV infection was quantified by counting EGFP-positive cells. Infection was quantified in cell lines from the female reproductive tract, brain tissue, and colon tissue (0.36%-3.15%). Virus replicated in the infected cells and the progeny virus were infectious for CD4 cells, HeLa-CD4, and CEM T lymphocytes. Furthermore, we found that infection of these epithelial and brain cell lines is independent of gp120. The results from the infection of CD4 epithelial cells suggest that HIV can traverse epithelial cell layers by infecting them through a gp120-independent mechanism. Infection of glial and neuronal cell lines suggests that HIV infection of these cells is a probable mechanism for HIV pathogenicity in the brain and a possible cause for persistent infection in patients.

Involvement of claudin-7 in HIV infection of CD4(-) cells.

BACKGROUND: Human immunodeficiency virus (HIV) infection of CD4(-) cells has been demonstrated, and this may be an important mechanism for HIV transmission. RESULTS: We demonstrated that a membrane protein, claudin-7 (CLDN-7), is involved in HIV infection of CD4(-) cells. A significant increase in HIV susceptibility (2- to 100-fold) was demonstrated when CLDN-7 was transfected into a CD4(-) cell line, 293T. In addition, antibodies against CLDN-7 significantly decreased HIV infection of CD4(-) cells. Furthermore, HIV virions expressing CLDN-7 on their envelopes had a much higher infectivity for 293T CD4(-) cells than the parental HIV with no CLDN-7. RT-PCR results demonstrated that CLDN-7 is expressed in both macrophages and stimulated peripheral blood leukocytes, suggesting that most HIV virions generated in infected individuals have CLDN-7 on their envelopes. We also found that CLDN-7 is highly expressed in urogenital and gastrointestinal tissues. CONCLUSION: Together these results suggest that CLDN-7 may play an important role in HIV infection of CD4(-) cells.