Differential binding of IgG and IgA to mucus of the female reproductive tract.

Cells of the endocervix are responsible for the secretion of mucins, which provide an additional layer of protection to the female reproductive tract (FRT). This barrier is likely fortified with IgA as has previously been shown in the gastrointestinal tract and lungs of mice. Mucus associated IgA can facilitate clearance of bacteria. While a similar function for IgG has been proposed, an association with mucus has not yet been demonstrated. Here we find that IgA and IgG are differentially associated with the different types of mucus of the FRT. We observed that while both IgA and IgG are stably associated with cervical mucus, only IgG is associated with cervicovaginal mucus. These findings reveal that antibodies can bind tightly to mucus, where they can play a significant role in the fortification of the mucus barriers of the FRT. It may be possible to harness this interaction in the development of vaccines designed to protect the FRT mucosal barriers from sexually transmitted diseases such as HIV.

A respiratory syncytial virus replicon that is noncytotoxic and capable of long-term foreign gene expression.

Respiratory syncytial virus (RSV) infection of most cultured cell lines causes cell-cell fusion and death. Cell fusion is caused by the fusion (F) glycoprotein and is clearly cytopathic, but other aspects of RSV infection may also contribute to cytopathology. To investigate this possibility, we generated an RSV replicon that lacks all three of its glycoprotein genes and so cannot cause cell-cell fusion or virus spread. This replicon includes a green fluorescent protein gene and an antibiotic resistance gene to enable detection and selection of replicon-containing cells. Adaptive mutations in the RSV replicon were not required for replicon maintenance. Cells containing the replicon could be cloned and passaged many times in the absence of antibiotic selection, with 99% or more of the cells retaining the replicon after each cell division. Transient expression of the F and G (attachment) glycoproteins supported the production of virions that could transfer the replicon into most cell lines tested. Since the RSV replicon is not toxic to these cultured cells and does not affect their rate of cell division, none of the 8 internal viral proteins, the viral RNA transcripts, or the host response to these molecules or their activities is cytopathic. However, the level of replicon genome and gene expression is controlled in some manner well below that of complete virus and, as such, might avoid cytotoxicity. RSV replicons could be useful for cytoplasmic gene expression in vitro and in vivo and for screening for compounds active against the viral polymerase.