SEA-PHAGES | Superinfection immunity

Link to this post \| posted today, 15:42
pia1@pitt.edu	Does superinfection immunity completely block a lysogen from being reinfected by the same temperate phage that established the lysogeny?

Link to this post \| posted today, 15:50
debbie	If both phages have the same repressor, then a lysogen of one should not be infected by the other phage. We have examples where the phages of the same cluster do infect a lysogen, but their repressor is broken/absent. We also have examples where a phage can carry 2 different repressors (why not, right?) and keep keep out phages of a different cluster. in order for a phage to maintain lysogeny, a repressor can be essential. Papers include Cell, 2023. Other papers of D29. A paper about phage Tweety…. Lots of examples. debbie

Link to this post | posted today, 15:50

debbie

If both phages have the same repressor, then a lysogen of one should not be infected by the other phage. We have examples where the phages of the same cluster do infect a lysogen, but their repressor is broken/absent. We also have examples where a phage can carry 2 different repressors (why not, right?) and keep keep out phages of a different cluster. in order for a phage to maintain lysogeny, a repressor can be essential.
Papers include Cell, 2023. Other papers of D29. A paper about phage Tweety….
Lots of examples.
debbie

Link to this post \| posted today, 15:54
viknesh	pia1@pitt.edu Does superinfection immunity completely block a lysogen from being reinfected by the same temperate phage that established the lysogeny? In general, homotypic superinfection immunity is complete, meaning that a given phage will not be able to complete a productive infection in a lysogen of that phage – you wont expect to see plaques. At some low frequency, you can expect to see plaques. These are often the result of a mutant phage within the population of phage in your lysate that cannot be repressed. You might imagine, for example, a mutation in the binding site of the immunity repressor that weakens binding and repression. If your phage is behaving counter to these generalized outcomes, please do share!

Link to this post | posted today, 15:54

viknesh

pia1@pitt.edu
Does superinfection immunity completely block a lysogen from being reinfected by the same temperate phage that established the lysogeny?

In general, homotypic superinfection immunity is complete, meaning that a given phage will not be able to complete a productive infection in a lysogen of that phage – you wont expect to see plaques. At some low frequency, you can expect to see plaques. These are often the result of a mutant phage within the population of phage in your lysate that cannot be repressed. You might imagine, for example, a mutation in the binding site of the immunity repressor that weakens binding and repression. If your phage is behaving counter to these generalized outcomes, please do share!

Link to this post \| posted today, 18:10
pia1@pitt.edu	Thanks, Debbie and Vik. I’ve tried several times to attach the results slide as a PPT or JPG, but it isn’t going through. Would it be okay if I email the results instead? I’m trying to share the superinfection immunity test outcomes for phages Dmitri and Arri. Dmitri behaved as expected (no clearing or plaques on the lysogen lawn), but Arri’s results were unexpected (EOP ~10⁻⁴). I’d appreciate any thoughts you might have. Of course, we’ll need to repeat the experiments. 1.74Mb

Link to this post | posted today, 18:10

pia1@pitt.edu

Thanks, Debbie and Vik. I’ve tried several times to attach the results slide as a PPT or JPG, but it isn’t going through. Would it be okay if I email the results instead? I’m trying to share the superinfection immunity test outcomes for phages Dmitri and Arri. Dmitri behaved as expected (no clearing or plaques on the lysogen lawn), but Arri’s results were unexpected (EOP ~10⁻⁴). I’d appreciate any thoughts you might have. Of course, we’ll need to repeat the experiments.

Link to this post \| posted today, 18:11
pia1@pitt.edu	This time, it did go through. So please ignore what I said about emailing.

Link to this post \| posted today, 18:43
viknesh	pia1@pitt.edu Thanks, Debbie and Vik. I’ve tried several times to attach the results slide as a PPT or JPG, but it isn’t going through. Would it be okay if I email the results instead? I’m trying to share the superinfection immunity test outcomes for phages Dmitri and Arri. Dmitri behaved as expected (no clearing or plaques on the lysogen lawn), but Arri’s results were unexpected (EOP ~10⁻⁴). I’d appreciate any thoughts you might have. Of course, we’ll need to repeat the experiments. Ping, have you been able to reproduce these results? As an aside, when spotting a dilution series on a plate, I would avoid circling each spot (or at least erasing the circles before imaging) as they are distracting and not great for publication. Since we'd love to be able to use these data for potential publications, consider just listing the dilutions next to the spots or preparing a grid. Edited today, 18:49

Link to this post | posted today, 18:43

viknesh

pia1@pitt.edu
Thanks, Debbie and Vik. I’ve tried several times to attach the results slide as a PPT or JPG, but it isn’t going through. Would it be okay if I email the results instead? I’m trying to share the superinfection immunity test outcomes for phages Dmitri and Arri. Dmitri behaved as expected (no clearing or plaques on the lysogen lawn), but Arri’s results were unexpected (EOP ~10⁻⁴). I’d appreciate any thoughts you might have. Of course, we’ll need to repeat the experiments.

Ping, have you been able to reproduce these results?

As an aside, when spotting a dilution series on a plate, I would avoid circling each spot (or at least erasing the circles before imaging) as they are distracting and not great for publication. Since we'd love to be able to use these data for potential publications, consider just listing the dilutions next to the spots or preparing a grid.

Edited today, 18:49

Link to this post \| posted today, 18:47
debbie	Hi Ping, You have a seqeunce right? And you have identified the repressor. You can compare it to other DC1 phage sequences. And you have other DC1 phages in your U of Pittsburgh collection. Test those! Consider compiling the data of DC1 phages, their infections patterns and their genomic comparisons (especially of the repressor sequence). And note that the simplest answer may be the best one - is your lysate pure? And I agree with Vic - grids of dilutions presented in a comparative way (when you repeat) will produce publication quality pictures. debbie

Link to this post | posted today, 18:47

debbie

Hi Ping,
You have a seqeunce right? And you have identified the repressor.
You can compare it to other DC1 phage sequences. And you have other DC1 phages in your U of Pittsburgh collection. Test those! Consider compiling the data of DC1 phages, their infections patterns and their genomic comparisons (especially of the repressor sequence).

And note that the simplest answer may be the best one - is your lysate pure?

And I agree with Vic - grids of dilutions presented in a comparative way (when you repeat) will produce publication quality pictures.
debbie

Link to this post \| posted 13 minutes ago
pia1@pitt.edu	Debbie and Vic, thank you both for all the helpful suggestions! To Vic’s question about reproducibility: No, these experiments haven’t been repeated yet, but they definitely need to be. I first saw the unusual results for Arri over the summer and have been wondering about them ever since. I brought it up today because I’m now seeing similar patterns with other phages on my students’ plates, and I’m worried I might be missing something. To Debbie’s question about lysate purity: I share that concern. I revived Arri by plating the phage stock stored at Pitt and then flooded the webbed plate. So if there was another phage in the original stock at a low titer (low enough not to interfere with sequencing), it could have been propagated along with Arri. Do you have any suggestions for confirming purity, Debbie?

Link to this post | posted 13 minutes ago

pia1@pitt.edu

Debbie and Vic, thank you both for all the helpful suggestions!

To Vic’s question about reproducibility: No, these experiments haven’t been repeated yet, but they definitely need to be. I first saw the unusual results for Arri over the summer and have been wondering about them ever since. I brought it up today because I’m now seeing similar patterns with other phages on my students’ plates, and I’m worried I might be missing something.

To Debbie’s question about lysate purity: I share that concern. I revived Arri by plating the phage stock stored at Pitt and then flooded the webbed plate. So if there was another phage in the original stock at a low titer (low enough not to interfere with sequencing), it could have been propagated along with Arri. Do you have any suggestions for confirming purity, Debbie?

Recent Activity

Superinfection immunity