Hello @Shilpi - G. 

I am not very clear with your question. Anyhow, here are some suggestions that may help you to measure the mRNA level of your target gene (which also correspond to the protein expression level) and subsequently to identify whether the (expressed) protein is secreted type or not. 

1. Measurement of the transcription (mRNA) and expression (protein) levels of your target gene during Infection:

      a. Infect human cells (i.e. HUVECs, HEK 293 cells, ...) with freshly prepared bacteria (from culture) at different times of coincubation (i.e. 0h, 30min, 1h, ...) 

      b. Collect media from the bacteria-human cell coculture supernatants and media from 0.05% sodium deoxycholate–PBS-lysed bacteria-human cells (after centrifugation).

      c. Extract total bacterial RNA using TRIzol reagent and digest with RNase-Free DNase. 

      d. Generate cDNA from the extracted total mRNA by reverse transcription using a cDNA Synthesis Kit.

      e. Using the cDNA as template, measure the mRNA (level) with qPCR using a SYBR Ex-Taq Kit where 16S RNA gene of your bacteria will be used as the inner reference.

      f. Collect supernatants as in step b. to detect protein concentrations using a Protein Concentration Assay Kit or Nanodrop; and immunodetect the target protein with Western blot assay. 

2. Determine the secretion of the protein during infection .

      a. Proceed as described above in 1.a., and collect only total proteins in all the supernatants (without lysis of bacterial or human cells)  

      b. Perfom western blot assay for the immunodetection of your bacterial target protein in the supernatant protein specimens (always at different coincubation times). Thus you will get the estimated time required for your protein to be properly secreted.

The paper in this link may help you to setup the experiment.

Good luck!

https://www.ncbi.nlm.nih.gov/pubmed/24277745