微生物学

Time to AIDS infection is longer with HIV-2, compared to HIV-1, but without antiretroviral therapy both infections will cause AIDS-related mortality. In HIV-2 infection, monitoring of antiretroviral treatment (ART) efficacy is challenging since a large proportion of HIV-2-infected individuals displays low or undetectable plasma RNA levels. Hence, quantification of cellular DNA load may constitute an alternative method for monitoring ART efficacy. Moreover, sensitive HIV-2 DNA quantification protocols are also important for the characterization of the HIV-2 reservoirs, and ultimately for the development of HIV-2 cure strategies. We have developed a sensitive and robust HIV-2 DNA quantification protocol based on whole blood as DNA source, including normalization of leukocyte cell numbers using parallel quantification of the single copy porphobilinogen deaminase gene. The specificity and sensitivity of the assay was 100%. The limit of detection was 1 copy and limit of quantification was 5 copies. When applying this protocol to HIV-2 infected, it was found that HIV-2 viral DNA was detectable in individuals in whom viral RNA was undetectable or under quantification level. Thus, this method provides a sensitive approach to HIV-2 DNA viral quantification from whole blood of HIV-2 infected patients.

Human hepatic cancer cell lines such as HepG2, Huh7, and HLE cannot get infected with Hepatitis B virus (HBV) due to lack of an HBV receptor(s). Transfection with HBV genome has so far been referred as a tool to mimic HBV infection. However, since sodium taurocholate cotransporting polypeptide (NTCP) was identified as a functional receptor for HBV (Yan et al., 2012), hepatocyte cell lines that were stably transfected with a plasmid for NTCP expression have been used for HBV infection. This protocol is designed for infection with HBV in human hepatocyte cell line HepG2 expressing NTCP (HepG2-hNTCP-C4 cells; Iwamoto et al., 2014) or primary human hepatocytes (PHHs). In this section, we also describe one of the methods for the assessment of HBV infection: Quantification of the intracellular encapsidated HBV DNA.

Almost all individuals infected with human immunodeficiency virus (HIV) are also infected with cytomegalovirus (CMV) and Epstein Barr virus (EBV). The aims of our studies have included characterizing and measuring the latent HIV reservoir and understanding the association between asymptomatic replication of CMV (and other herpesvirus, including EBV) and this HIV reservoir (Gianella et al., 2014). This protocol was designed to simultaneously co-extract DNA and RNA from the same peripheral blood mononuclear cell (PBMC) aliquot and quantify HIV, CMV and EBV DNA, as well as HIV RNA using droplet digital PCR (ddPCR).

For collection and processing of male genital secretions and quantification of HIV RNA and DNA from seven human herpesviruses from seminal plasma, refer to protocol “Quantification of HIV RNA and Human Herpesvirus DNA in Seminal Plasma” (Vargas-Meneses et al., 2015).

Multiple viruses can co-infect the genital tract, modifying the immunologic and virologic milieu and possibly playing a role in viral transmission and pathogenesis. The aim of our studies has been to understand the complex relationships between HIV-1 RNA, and multiple human herpesviruses known to frequently replicate in the genital tract of HIV-infected men (i.e. cytomegalovirus [CMV], Epstein Bar virus [EBV], herpes simplex virus [HSV] types 1 and 2, and human herpesviruses [HHV] 6, 7 and 8) (Gianella et al., 2013a; Gianella et al., 2013b; Gianella et al., 2013c; Gianella et al., 2014). This protocol was designed to collect and process male genital secretion (GS), and to isolate and further quantify HIV RNA and DNA of seven HHV from seminal plasma using quantitative real time PCR technology.

The reverse transcription (RT) reaction is a critical step in HIV-1 life cycle. It is very strongly regulated and the target of several restriction factors (TRIM5α, APOBECs, SAMHD1, etc.). The progress of reverse transcription can be followed by measuring viral DNA by quantitative PCR (qPCR). This method is sensitive enough to allow detection of low amounts of HIV-1 DNA in infected cells and discriminate between several types of reverse transcription intermediates (so called 《early》 and 《late》 RT products, 2 Long Terminal Repeat (LTR) circles, integrated DNA).