cThe cytidine deaminase APOBEC3G (A3G) exerts a multifaceted antiviral effect against HIV-1 infection. First, A3G was shown to be able to terminate HIV infection by deaminating the cytosine residues to uracil in the minus strand of the viral DNA during reverse transcription. Also, a number of studies have indicated that A3G inhibits HIV-1 reverse transcription by a non-editingmediated mechanism. However, the mechanism by which A3G directly disrupts HIV-1 reverse transcription is not fully understood. In the present study, by using a cell-based coimmunoprecipitation (Co-IP) assay, we detected the direct interaction between A3G and HIV-1 reverse transcriptase (RT) in produced viruses and in the cotransfected cells. The data also suggested that their interaction did not require viral genomic RNA bridging or other viral proteins. Additionally, a deletion analysis showed that the RT-binding region in A3G was located between amino acids 65 and 132. Overexpression of the RT-binding polypeptide A3G 65-132 was able to disrupt the interaction between wild-type A3G and RT, which consequently attenuated the anti-HIV effect of A3G on reverse transcription. Overall, this paper provides evidence for the physical and functional interaction between A3G and HIV-1 RT and demonstrates that this interaction plays an important role in the action of A3G against HIV-1 reverse transcription. Several host proteins have been identified as intrinsic restriction factors because of their ability to inhibit HIV replication and/or dissemination (2, 31, 41, 52). Among them, the apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3G; here referred to as A3G) is the one that restricts HIV-1 replication through more than one mechanism (17,32,37,38,40). In the absence of the HIV-1 viral infectivity factor (Vif), A3G is incorporated into progeny viruses through its interaction with the nucleocapsid (NC) domain of the Gag protein and/or viral RNA (1,15,56,63). Once these progeny viruses initiate new infection, the incorporated A3G will deaminate the cytidine to uridine in the viral minus-strand DNA during reverse transcription, resulting in hypermutation in the provirus. As a result, the HIV-1 proviral DNA will be no longer functional or degrade rapidly (21,32,38,64). Additionally, the mutated proviral DNA may produce defective or truncated viral polypeptides that represent a significant source of major histocompatibility complex class I (MHC-I)-restricted epitopes to activate HIV-1-specific CD8 ϩ cytotoxic T lymphocytes (CTLs) (12).Reverse transcription catalyzed by HIV-1 reverse transcriptase (RT) is a critical step for HIV-1 to establish its replication cycle. In infected cells, RT employs tRNA 3Lys and the polypurine tract as primers and converts the viral genomic RNA into doublestranded viral DNA (23). This process is catalyzed by both the DNA polymerase and RNase H activities of RT (23,49). Interestingly, in addition to the deaminase activity, A3G has also been shown to directly inhibit HIV-1 reverse transcription by a non...

Clin Invest Med 2008; 31 (1): E8-E15. AbstractObjective: Ki-67 is a proliferation-associated nuclear antigen and is expressed in all cycling cells except for resting cells in the G0-phase. PCNA is an acidic nuclear protein and has been recognized as a histologic marker for the G1/ S phase in the cell cycle. Ki-67and PCNA labeling indices are considered to reflect cell proliferation, particularly, growth fraction. The purpose of this study is to investigate the expression levels of Ki-67 and PCNA in prostate cancer (PCa) and benign prostatic hyperplasia (BPH) and their potential on the early diagnosis of PCa. Methods: Human prostate cancer cell lines LNCaP and PC-3, human normal prostate epithelial cell line HuPEC, tissues from patients with PCa (121 cases) and BPH (45) and 36 normal cases were examined for the expression of Ki-67 and PCNA by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Then, the association of Ki-67 and PCNA expression with clinical grading of PCa was analyzed by immunohistochemistry staining. Results: The ratios of PCNA and Ki-67 expression levels in LNCaP and PC-3 were higher (P<0.05, P<0.001) than that in HuPEC. The two markers were differentially expressed in three tissues and showed increased expression in PCa (P<0.05) and BPH (P<0.05), relative to human normal prostate tissues. Compared with BPH, the ratio of Ki-67 and PCNA expressed in tumour tissue was increased (P<0.05). The increase of Ki-67 was greater than that of PCNA. Expression of the two markers increased after different grading of PCa cases Prostate cancer (PCa) is the second most frequent cause of male cancer-related death in the United States of America (USA) and Western Europe. Its incidence is continuously rising, with over 200 000 new cancers and 35 000~40 000 deaths per year, 1 Carcinogenesis and the mechanisms influencing the progression and prognosis of PCa is a multistep process, involving both genetic insults to epithelial cells and changes in epithelial-stromal interactions. 2 Despite extensive research PCa is not understood.There are two proliferative markers-Ki-67 and proliferating cell nuclear antigen (PCNA). Ki-67 antigen is expressed in proliferative cells throughout the G1, S, G2, and M phases, and provides a reliable index of cellular proliferation 3,4 PCNA is an acidic nuclear protein, expressed mainly in phase S of the cellular cycle. It becomes active, in various tissues par-

Background: HIV-1 integration is promoted by viral integrase and its cellular cofactors. Results: Nucleoporin 62 interacts with HIV-1 integrase in chromatin, and shRNA knockdown of nucleoporin 62 was able to impair integrase chromatin association and viral replication. Conclusion: Interaction of nucleoporin 62 and HIV-1 integrase contributes to viral DNA integration. Significance: A new nucleoporin was identified as an integrase-binding cofactor required for HIV-1 integration and replication.

Background Early gut microbial colonization is important for postnatal growth and immune development of the chicken. However, at present, commercial chickens are hatched and raised without adult hens, thus are cut off from the microbiota transfer between hens and chicks. In this study, we compared the gut microbiota composition between hen-reared and separately reared chicks, and its impact on the resistance to H9N2 avian influenza virus, with the motive of investigating the impact of this cutoff in microbiota transfer. Results We used the 16SrRNA sequencing method to assess the composition of the gut microbiota in chicks represented by three hen-reared groups and one separately reared group. We found that the diversity of gut microbes in the chicks from the three hen-reared groups was more abundant than in the separately reared group, both at the phylum and genus levels. Our findings highlight the importance of early parental care in influencing the establishment of gut microbiota in the early life of chicks. SourceTracker analysis showed that the feather and cloaca microbiota of hens are the main sources of gut microbiota of chicks. After H9N2 exposure, the viral infection lasted longer in the separately reared chicks, with the viral titers in their oropharyngeal swabs being higher compared to the hen-reared chicks at day 5 post-infection. Interestingly, our results revealed that the gut microbiota of the hen-reared chicks was more stable after H9N2 infection in comparison to that of the separately reared chicks. Conclusions Microbiota transfer between the hens and their chicks promotes the establishment of a balanced and diverse microbiota in the early life of the chicks and improves microbiota stability after H9N2 challenge. These findings advance our understanding of the protective role of gut microbiota in the early life of chicks and should be instrumental in improving chick rearing in the commercial poultry industry.

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