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Mouse mammary tumor virus (MMTV) is a pH-dependent virus that uses mouse transferrin receptor 1 (TfR1) for entry into cells. Previous studies demonstrated that MMTV could induce pH 5-dependent fusion-from-with of mouse cells. Here we show that the MMTV envelope-mediated cell–cell fusion requires both the entry receptor and low pH (pH 5). Although expression of the MMTV envelope and TfR1 was sufficient...
The V3 loop of HIV-1 gp120 is considered occluded on many primary viruses. However, virus sensitivity to neutralization by different V3 mAbs often varies, indicating that access to V3 is not restricted equally for all antibodies. Here, we have sought to gain a better understanding of these restrictions by determining the neutralizing activities of 7 V3 mAbs (19b, 39F, CO11, F2A3, F530, LA21, and LE311)...
Hantaan virus (HTNV) is a pathogenic hantavirus that causes hemorrhagic fever with renal syndrome (HFRS). HTNV infection is mediated by αvβ3 integrin. We used protein blots of Vero E6 cell homogenates to demonstrate that radiolabeled HTNV virions bind to gC1qR/p32, the acidic 32-kDa protein known as the receptor for the globular head domain of complement C1q. RNAi-mediated suppression of gC1qR/p32...
Cholesterol present in the plasma membrane of target cells has been shown to be important for the infection by SARS-CoV. We show that cholesterol depletion by treatment with methyl-β-cyclodextrin (mβCD) affects infection by SARS-CoV to the same extent as infection by vesicular stomatitis virus-based pseudotypes containing the surface glycoprotein S of SARS-CoV (VSV-ΔG-S). Therefore, the role of cholesterol...
One of most intriguing features of the HIV-1 subtype B epidemic in Brazil is the high frequency of isolates exhibiting tryptophan (W) in the tetramer (GWGR) at the tip of the V3 loop. We observed that the frequencies of glutamic and aspartic acids at site 25 of the V3 loop are quite distinct in GWGR isolates compared with viruses with other tetramers. The basic amino acids at sites 11 and 25 of V3...
Several echoviruses use decay accelerating factor (DAF) as a cell surface receptor. However, most of them require additional cell surface coreceptors. We investigated the respective roles of DAF and class I human leukocyte antigen (HLA) molecules in the early steps of the echovirus 11 (EV11) lifecycle in rhabdomyosarcoma (RD) cells. EV11 infection was inhibited at an early stage by anti-β2-microglobulin...
Comprehension of the pathogenetic potential of human parvovirus B19 requires the definition of the complete spectrum of cellular tropism and a functional analysis of the viral genome in infected cells. In this study, we carried out a systematic functional analysis of B19 virus genome in the course of infection of susceptible bone marrow mononuclear cells and myeloblastoid UT7/EpoS1 cells, in terms...
The replication complex of Red clover necrotic mosaic virus (RCNMV) has been shown to possess silencing suppression activity. Here a newly developed viral-based assay for the identification of silencing suppression activity was used to provide evidence for a second, mechanistically distinct method of silencing suppression provided for by the RCNMV movement protein (MP). This new assay relies on Turnip...
To counteract the problems associated with the purification of HIV envelope, we developed a new purification method exploiting the high affinity of a peptide mimicking CD4 towards the viral glycoprotein. This miniCD4 was used as a ligand in affinity chromatography and allowed the separation in one step of HIV envelope monomer from cell supernatant and the capture of pre-purified trimer. This simple...
Tick-borne flaviviruses are maintained in nature in an enzootic cycle involving a tick vector and a vertebrate host. Thus, the virus replicates in two disparate hosts, each providing selective pressures that can influence virus replication and pathogenicity. To identify viral determinants associated with replication in the individual hosts, plaque purified Langat virus (TP21pp) was adapted to growth...
Ultraviolet (u.v.) inactivated coxsackievirus B3 (CVB3) induces rapid calcium flux in naïve BALB/c CD4+ T cells. CD4+ cells lacking decay accelerating factor (DAF−/−) show little calcium flux indicating that virus cross-linking of this virus receptor protein is necessary for calcium signaling in CVB3 infection. Interaction of CVB3 with CD4+ cells also activates NFAT DNA binding. To show that NFAT...
Half of subtype B Brazilian HIV-1 harbors the V3 tip GWGR instead of the GPGR. To investigate the evolution of GW variants, we analyzed 81 env sequences and 5 full-length GW genomes from antiretroviral-naïve individuals sampled between 1983 and 1999. Phylogenetic analysis indicated that GW strains intermingle in the tree with other subtype B sequences. The mean d N /d S values of GW...
We have documented that epidermal growth factor receptor protein tyrosine kinase (EGFR-PTK) signaling negatively affects intracellular trafficking and transduction efficiency of recombinant adeno-associated virus 2 (AAV2) vectors. Specifically, inhibition of EGFR-PTK signaling leads to decreased ubiquitination of AAV2 capsid proteins, which in turn, facilitates viral nuclear transport by limiting...
FOXP3 is a necessary transcription factor for the development and function of CD4+ regulatory T-cells (Tregs). The role of Tregs in HIV-1 infection remains unclear. Here, we show that expression of FOXP3 in primary human CD4 T-cells significantly inhibits HIV-1 infection. Since FOXP3 inhibits NFAT activity, and NFAT proteins contribute to HIV-1 transcription, we explore a transcriptional repressive...
The full-length of the occlusion body (OB) protein gene of Penaeus monodon nucleopolyhedrovirus (PemoNPV) was successfully isolated. The OB gene sequence contained an open reading frame (ORF) of 1359 nucleotides encoding a protein of 452 amino acid residues with a predicted molecular mass of 50.6 kDa. A putative late promoter element, TAAG, was identified 72 nt upstream of the translation start site...
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