12th International AIDS Conference Geneva, Switzerland - June 28-July 3, 1998

Int Conf AIDS 1998 Jun 28-Jul 3; 12:4-5 (abstract no. 11112)

Naif H, Alali M, Li S, French R, Stewart G, Cunningham A
Centre for Virus Research, Westmead Hospital, Sydney, NSW, Australia.

OBJECTIVES: To investigate the mechanism of infection of an HIV+ve person homozygous for CCR5 Δ32 and identification of co-receptors other than CCR5 that are used by isolated viruses.

METHODS: The patient was repeatidly positive for HIV antibody by ELISA and western blot. Homozygosity for CCR5 Δ32 mutation was detected by PCR and confirmed by DNA sequencing. Virus growth in MT2 cell line, macrophages and lymphocytes was measured by CPE, p24 antigen ELISA and DNA-PCR. The original virus was cocultured with PBMCs from donors (including relatives) who were normal or homozygous for CCR5 Δ32 mutation.

RESULTS: Recently we have identified a person homozygous for CCR5 Δ32 who was infected with HIV. The homozygous CCR5 mutation in this person was identical to the published 32 nucleotide deletion found in approximately 1% of Caucasians. His HIV-ve brother was also homozygous for the Δ32 mutation, therefore his cells were utilized as donor cells for culture of defined strains of virus. The original HIV isolate grew rapidly in cultures from both CCR5 positive PBMCs and his brother's cells. The virus demonstrated dual tropism growing in both T cell lines (MT-2) and primary macrophages, exhibiting a similar pattern of HIV replication to other clinical isolates but with a relatively low productive infection. Sequencing of the V3 region directly from patient's cellular DNA revealed relatively minor changes compared with B subtype consensus sequence. Sequencing is currently being repeated with isolates from the cocultures of both CCR5 Δ32/Δ32 and CCR5 wild type cells. The envelope region has also been cloned and expressed into E. coli in attempt to eventually be expressed in CHO cells. Co-receptor usage by this virus was examined using HOS cells kindly donated by Dr D. Littman. It predominantly used BONZO (STRL33) but also used others.

CONCLUSIONS: This study demonstrates that homozygosity for CCR5 Δ32 is not absolutely protective against HIV infection and that infection may occur using other alternative coreceptors such as STRL33. The viral isolates were confirmed to be a dual tropic with relatively slow growth in primary cells. No major changes were found in the sequence of the V3 region of the HIV strain, directly from the patient's cells.

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