1 patent only protects the created sequence (such as the sequence of constructing plasmid), and does not protect the naturally occurring sequence (such as the sequence of human pathogenic gene);
The technology protected by patent should not be made public before the patent application date. If you can find this sequence in places like NCBI 10 and articles 20 years ago, even if there is patent protection, it has expired now;
If this sequence is constructed by yourself, and you have no relevant reports when searching for the latest literature, or even entrust an authoritative organization to conduct novelty search, you have a great chance to apply for a new patent. If you don't intend to apply for a new patent and just want to use it without infringement, then release this sequence from public channels as soon as possible. For example, publish it on your own blog. As long as it is made public, no one will have a chance to apply for a patent in the future.
On the patent website, only the patent has entered the public period can you find the relevant information, but if you have applied but have not entered the public period, you can't find it.