title: Calculating HIV-1 infectious titre using a virtual TCID(50) method.
abstract: Studies of HIV-1 replication kinetics and fitness require an accurate determination of the level of infectious HIV-1 present in virus stocks. The standard technique for measuring the level of replication-competent infectious virus in culture supernatants or patient samples is the tissue culture dose for 50% infectivity (TCID(50)), which provides an accurate assessment of the level of infectious HIV-1. However, it is a time-consuming technique which typically takes two or more weeks to complete and requires PHA-stimulated PBMC from HIV-1 seronegative donors or an appropriate cell line. Thus rapid, cell-free surrogate measures for TCID(50) are desirable. Here, we introduce the virtual TCID(50) technique: a new cell-free method estimating a surrogate of infectious titer by comparing the reverse transcriptase activity in virus stock to that of reference viruses with a known TCID(50) value. We have demonstrated that the virtual TCID(50) obtained through this technique is comparable to the actual infectious TCID(50). This method greatly simplifies the process of accurate HIV-1 titration and is particularly beneficial for studies which require titration of large number of HIV-1 isolates.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Gao
authors.forename: Immaculate
authors.initials: I
authors.lastname: Nankya
authors.forename: Awet
authors.initials: A
authors.lastname: Abraha
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Troyer
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Nelson
authors.forename: Andrea
authors.initials: A
authors.lastname: Rubio
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Arts
mesh_terms: D002478:Cells, Cultured; D054303:HIV Reverse Transcriptase / Q000378:metabolism*; D015497:HIV-1 / Q000201:enzymology / Q000472:pathogenicity*; D006801:Humans; D007963:Leukocytes, Mononuclear; D012015:Reference Standards; D014773:Virology / Q000379:methods*
chemical_list: C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase