Dr Desrosiers Research Laboratory

Dr Desrosiers Research Laboratory

Description of Research

The research trajectory of the Desrosiers laboratory has been largely driven by discovery of new viruses and their development into new models of human disease. Dr. Desrosiers led the team and was senior author on the Science publication that described the discovery of the simian immunodeficiency virus and its association with AIDS in rhesus monkeys [1]. This report followed by almost exactly one year the first descriptions of HIV-1 in humans with AIDS. The Desrosiers laboratory is also credited with the discovery of a gamma-2 herpesvirus of rhesus monkeys that is a close homolog of the human Kaposi sarcoma herpesvirus (KSHV) [2]. My laboratory also described the discovery of new type D retroviruses that are a major cause of morbidity and mortality in macaque monkey colonies [3].

The Desrosiers laboratory was the first to define an infectious, pathogenic, molecular clone of SIV, the first of its kind for any HIV, SIV, or any lentivirus [4]. Virus derived from transfection of this full-length cloned proviral DNA is not only replication competent but also fully capable of causing AIDS in monkeys. This SIVmac239 remains the cloned virus of choice and is widely used around the world. The Desrosiers laboratory has used this clone to make a number of important contributions to the understanding of the relative importance and functional role of individual genetic elements of the virus. Each of the six so-called “auxiliary” genes of the virus have been deleted individually and the properties of these gene-deleted viruses have been defined in cell culture and upon experimental infection of rhesus monkeys [5]. Published work with SIV deleted of its nef gene has probably received the most attention. Working subsequently with physician-scientist John Sullivan at UMass Medical School, The Desrosiers laboratory demonstrated that an HIV-positive long-term nonprogressor who was part of a hemophilia cohort was, incredibly, infected with nef-deleted HIV-1 and only nef-deleted HIV-1 even dating back to his first visit [6]. This remarkable case has been largely superceded by a group of 8 HIV-infected individuals in Australia, all infected by the same blood donor, who are all infected only with nef-deleted HIV-1. The degree of attenuation of nef-deleted SIV in monkeys approximates the degree of attenuation of nef-deleted HIV-1 in people. The Desrosiers laboratory has also used this system to characterize the MHC-downregulating activity of the virus, the NF-kB-inducing activity of the virus, and the genetic determinants and physiologic relevance of macrophage tropism.

In an extensive series of publications, the remarkable protective capacity of live-attenuated nef-deleted strains of SIV, including strains with deletions of multiple genetic elements, has been demonstrated [7]. In fact, the protective capacity of nef-deleted SIV to this day remains the gold standard for vaccine protection in the SIV-rhesus model. Nonetheless, the findings demonstrate that a protective vaccine against HIV-1 is going to be very difficult to develop.

On the herpesvirus front, the principle growth-transforming gene in the gamma-2 herpesvirus of New World primates, an oncogenic herpesvirus called herpesvirus saimiri, has been defined [8]. In subsequent work, equivalent growth-transforming activity of the equivalently-placed gene in the rhesus monkey rhadinovirus and in the human Kaposi sarcoma herpesvirus was demonstrated. The Desrosiers laboratory has also contributed to the understanding of gamma-2 herpesvirus late gene regulation, to receptor usage determined by the gH/gL glycoprotein complex of RRV, and to development of gamma-2 herpesviruses as gene transfer and vaccine vectors.

A good portion of the effort in the Desrosiers lab at the current time is directed to defining ways by which a protective sterilizing barrier may be achieved against SIV/HIV. The current focus is on two approaches: recombinant gamma-2 herpesvirus [9] and use of AAV vector to deliver persistent levels of potent broadly-neutralizing antibodies [10]. Some recent results with recombinant RRV are worthy of further note.

Glycoproteins of RRV and other herpesviruses have a “bad” codon usage (bad for expression) and are naturally trans-induced by the immediate early gene product ORF57. The viral-encoded glycoproteins of HIV, SIV and related lenti-retroviruses also have a bad codon usage and are naturally transinduced by rev. We noticed that the nature of the bad codon usage of RRV gH and gL was different from the bad codon usage of HIV and SIV gp160. We changed the codon usage for six amino acids in a SIV gp160 cassette to reflect the bad codon usage of RRV gH and gL. A total of 10.5% of the codons were changed and the rev-response element (the RRE) was left intact. The effects on expression were astounding. The SIV gp160 with the altered codon usage was no longer trans-induced by rev. However, this codon-altered gp160 cassette was now strongly trans-induced by RRV orf 57. Conversely, gH could be made rev-inducible only when the codon usage was made gp160-like. These results indicate that for both SIV rev and RRV orf57, two completely different virus families, transinduction was dependent on the nature of the bad codon usage. Furthermore, the codon-dependent transinduction appears to be intimately tied to cellular proteins called Schlafens. Rev induction of the natural gp160 sequence was potently inhibited by three of the five known Schlafens and orf57 induction of the codon-modifed version of gp160 was potently inhibited by all five Schlafens. The inhibitory activity of Schlafen 11 against codon-modified gp160 could be overcome by increasing concentrations of orf57 in a dose-dependent manner. Our results suggest that the cellular Schlafens serve as restriction factors for both herpesviruses and lentiviruses and that both orf57 and rev function at least in part to overcome this restriction. These observations have practical applications in attempts to use recombinant RRV as an experimental vaccine approach for AIDS in monkeys. The Desrosiers laboratory has previously published that recombinant RRV-SIVenv with a codon-optimized env cassette and CMV i.e. promoter did NOT elicit detectable anti-env antibody responses in monkeys. However, the new recombinant RRV-SIVenv with altered codon usage and orf57-inducible env expression IS eliciting anti-env antibody responses. Now perhaps this recombinant herpesvirus approach can match, or come close to matching, live attenuated SIV for the degree of vaccine protection that can be achieved.

Dr. Desrosiers has been a strong advocate for the need for more basic, discovery research in the search for an AIDS vaccine, and less government-funded product development, product manufacturing and clinical testing [11,12]. Dr Desrosiers gave a controversial plenary lecture at the 2008 national AIDS meeting summarizing this point of view. The dismal performance of vaccines in the six expensive human efficacy trials that have been carried out to date supports the point of view that we are a long way from finding a vaccine with a chance of showing the kinds of efficacy that we need.

References:

1. Daniel MD, Letvin NL, King NW, Kannagi M, Sehgal PK, et al. (1985) Isolation of T-cell tropic HTLV-III-like retrovirus from macaques. Science 228: 1201-1204.
2. Desrosiers RC, Sasseville VG, Czajak SC, Zhang X, Mansfield KG, et al. (1997) A herpesvirus of rhesus monkeys related to the human Kaposi’s sarcoma-associated herpesvirus. J Virol 71: 9764-9769.
3. Daniel MD, King NW, Letvin NL, Hunt RD, Sehgal PK, et al. (1984) A new type D retrovirus isolated from macaques with an immunodeficiency syndrome. Science 223: 602-605.
4. Kestler H, Kodama T, Ringler D, Marthas M, Pedersen N, et al. (1990) Induction of AIDS in rhesus monkeys by molecularly cloned simian immunodeficiency virus. Science 248: 1109-1112.
5. Kestler HW, 3rd, Ringler DJ, Mori K, Panicali DL, Sehgal PK, et al. (1991) Importance of the nef gene for maintenance of high virus loads and for development of AIDS. Cell 65: 651-662.
6. Kirchhoff F, Greenough TC, Brettler DB, Sullivan JL, Desrosiers RC (1995) Brief report: absence of intact nef sequences in a long-term survivor with nonprogressive HIV-1 infection. N Engl J Med 332: 228-232.
7. Daniel MD, Kirchhoff F, Czajak SC, Sehgal PK, Desrosiers RC (1992) Protective effects of a live attenuated SIV vaccine with a deletion in the nef gene. Science 258: 1938-1941.
8. Desrosiers RC, Bakker A, Kamine J, Falk LA, Hunt RD, et al. (1985) A region of the Herpesvirus saimiri genome required for oncogenicity. Science 228: 184-187.
9. Bilello JP, Manrique JM, Shin YC, Lauer W, Li W, et al. (2011) Vaccine protection against simian immunodeficiency virus in monkeys using recombinant gamma-2 herpesvirus. J Virol 85: 12708-12720.
10. Johnson PR, Schnepp BC, Zhang J, Connell MJ, Greene SM, et al. (2009) Vector-mediated gene transfer engenders long-lived neutralizing activity and protection against SIV infection in monkeys. Nat Med 15: 901-906.
11. Damania B, DeMaria M, Jung JU, Desrosiers RC (2000) Activation of lymphocyte signaling by the R1 protein of rhesus monkey rhadinovirus. J Virol 74: 2721-2730.
12. Desrosiers RC (2004) Prospects for an AIDS vaccine. Nat Med 10: 221-223.

Link to Dr. Ronald Desrosiers Publications