The nef Gene of SIVmac239 Is Necessary for Efficient Growth in H9 Cells.

AIDS viruses require an intact functional nef gene in order to induce disease. The nonpathogenic molecular cloned virus SIVmac239nef-deletion encodes a truncated nef gene. This attenuated reading frame is expressed both in vitro and in a virus-infected animal in vivo.

A candidate live inactivatable attenuated vaccine for AIDS.

The recent discovery of long term AIDS nonprogressors who harbor nef-attenuated HIV suggests that a naturally occurring live vaccine for AIDS may already exist. Animal models have shown that a live vaccine for AIDS, attenuated in nef, is the best candidate vaccine. There are considerable risks, real and perceived, with the use of live HIV vaccines.

Differential regulation of the virulence genes of Listeria monocytogenes by the transcriptional activator PrfA.

The two Listeria monocytogenes strains EGD and NCTC 7973 display a different regulation pattern of their PrfA-dependent genes. All PrfA-dependent genes from L. monocytogenes NCTC 7973 are much more efficiently transcribed in brain-heart infusion medium than those from strain EGD.

The nef gene from a long-term HIV type 1 nonprogressor.

We examined the nef gene of HIV-1 in a long-term nonprogressor to look for evidence suggesting an attenuated virus. The nef gene was previously shown to be required for induction of AIDS. Simian immunodeficiency virus (SIV) deleted in nef, while infectious, fails to sustain the high viral loads necessary for the induction of AIDS in infected adult rhesus monkeys.

Upstream U3 sequences in simian immunodeficiency virus are selectively deleted in vivo in the absence of an intact nef gene.

Major transcriptional control elements are located within the U3 region of the long terminal repeats (LTRs) of lentivirus and other retroviral genomes. The nef auxiliary gene of simian immunodeficiency virus (SIV) and human immunodeficiency virus overlaps about 70% of the 450- to 560-bp-long U3 region present in these primate lentiviruses. We analyzed viral DNA sequences present in rhesus monkeys infected with a mutant of SIVmac containing a 182-bp deletion in the region of nef that does not overlap the LTR.

Cloning and characterization of the S fimbrial adhesin II complex of an Escherichia coli O18:K1 meningitis isolate.

S fimbrial adhesins (Sfa), which are able to recognize sialic acid-containing receptors on eukaryotic cells, are produced by Escherichia coli strains causing urinary tract infections or newborn meningitis. We recently described the cloning and molecular characterization of a determinant, termed sfaI, from the chromosome of an E. coli urinary tract infection strain.

Importance of the nef gene for maintenance of high virus loads and for development of AIDS.

When rhesus monkeys were infected with a form of cloned SIVmac239 having a premature stop signal at the 93rd codon of nef, revertants with a coding codon at this position quickly and universally came to predominate in the infected animals. This suggests that there are strong selective forces for open functional forms of nef in vivo. Although deletion of nef sequences had no detectable effect on virus replication in cultured cells, deletion of nef sequences dramatically altered the properties of virus in infected rhesus monkeys.

Induction of AIDS in rhesus monkeys by molecularly cloned simian immunodeficiency virus.

Better understanding of the pathogenesis of acquired immunodeficiency syndrome (AIDS) would be greatly facilitated by a relevant animal model that uses molecularly cloned virus of defined sequence to induce the disease. Such a system would also be of great value for AIDS vaccine research. An infectious molecular clone of simian immunodeficiency virus (SIV) was identified that induces AIDS in common rhesus monkeys in a time frame suitable for laboratory investigation.

Molecular changes associated with replication of simian immunodeficiency virus in human cells.

The SIVmac239 infectious clone does not have a premature stop codon in its transmembrane protein (TMP) region and it produces full-length (41 kilodalton, kDa) TMP in macaque peripheral blood lymphocytes (PBL) in vitro and in vivo. However, viruses with truncated forms of TMP (28kDa) are selected during propagation in human cell types; truncated forms arise from point mutations, CAG (glutamine) to TAG (stop), in the viral genome. These results document molecular changes associated with adaptation of SIVmac for growth in human cells.

Nef genes of SIV.

Molecular clones of SIVmac were constructed that differed only in sequences within the nef gene. DEAE-transfection of viral DNA containing an open from of nef yielded virus that replicated with similar kinetics and to a similar extent in macaque peripheral blood lymphocyte (PBL) cultures as virus with a deletion or stop codon within nef. Rhesus monkeys that received each kind of molecularly cloned virus became infected.

Significance of premature stop codons in env of simian immunodeficiency virus.

The location of the translational termination codon for the transmembrane protein (TMP) varies in three infectious molecular clones of simian immunodeficiency virus from macaques (SIVmac). The SIVmac251 and SIVmac142 infectious clones have premature stop signals that differ in location by one codon; transfection of these DNAs into human HUT-78 cells yielded virus with a truncated TMP (28 to 30 kilodaltons [kDa]). The SIVmac239 infectious clone does not have a premature stop codon in its TMP-coding region.

Use of infectious molecular clones of simian immunodeficiency virus for pathogenesis studies.

Three infectious molecular clones of SIVmac and one of HIV-2 exhibit remarkable variation in their biological properties despite similarities in genome organization and sequence relatedness. Cloned viruses differed in their ability to grow in various cultured cells, in their ability to infect macaques, and in the location of the env stop codon. Sequences from the 3' end predict that at least three of the four clones do not have an intact, functional nef gene.

Characterization of infectious molecular clones of simian immunodeficiency virus (SIVmac) and human immunodeficiency virus type 2: persistent infection of rhesus monkeys with molecularly cloned SIVmac.

Infection of macaque monkeys with simian immunodeficiency virus (SIV) is probably the best animal model currently available for studying acquired immunodeficiency syndrome. In this report, we describe three infectious molecular clones of SIVmac and one of human immunodeficiency virus type 2 (HIV-2) and their use in the study of cell and species specificity, animal infection, and the relationship of gene sequence to function. Replication of the cloned viruses in different cell lines varied dramatically.

Simian immunodeficiency virus from African green monkeys.

Simian immunodeficiency virus (SIV) was isolated from the total peripheral blood mononuclear cell population and the monocyte-macrophage adherent cell population of three seropositive green monkeys originating from Kenya. SIV from these African green monkeys (SIVagm) was isolated and continuously produced with the MOLT-4 clone 8 (M4C18) cell line but not with a variety of other cells including HUT-78, H9, CEM, MT-4, U937, and uncloned MOLT-4 cells. Once isolated, these SIVagm isolates were found to replicate efficiently in M4C18, SupT1, MT-4, U937, and Jurkat-T cells but much less efficiently if at all in HUT-78, H9, CEM, and MOLT-4 cells.

Comparison of simian immunodeficiency virus isolates.

Information on the extent of genetic variability among non-human primate lentiviruses related to human immunodeficiency virus (HIV) is sorely lacking. Here we describe the isolation of two molecular clones from the simian immunodeficiency virus (SIV) and their use to derive restriction endonuclease maps of five SIV isolates from rhesus macaques and one from a cynomolgus macaque. Although similar, all six viral isolates are readily distinguishable; the single isolate from a cynomolgus macaque is the most different.

Nucleotide sequence of the alpha ribosomal protein operon of Escherichia coli.

In Escherichia coli some 19 transcription units encoding the 52 ribosomal proteins are scattered throughout the genome. One of the units, the alpha operon, encodes genes for the ribosomal proteins S13, S11, S4 and L17 as well as the alpha subunit of RNA polymerase. We report here the complete 3.