I have ClamAV engine 0.99.2 installed and it no longer works with currently provided definitions
is there some way to reformat the currently downloaded definition so they will work in this older environment?

(I have tried to upgrade my PCRE version but to no avail I am running RHEL 5.5 which I cannot upgrade for reasons I wont go into)

[root@wclceste5 pcre]# clamscan -v
LibClamAV Error: cli_pcre_compile: PCRE compilation failed at offset 20: unrecognized character after (?<
LibClamAV Error: cli_pcre_build: failed to build pcre regex
ERROR: Database initialization error: Malformed database

----------- SCAN SUMMARY -----------
Known viruses: 6744096
Engine version: 0.99.2
Scanned directories: 0
Scanned files: 0
Infected files: 0
Data scanned: 0.00 MB
Data read: 0.00 MB (ratio 0.00:1)
Time: 110.135 sec (1 m 50 s)
[root@wclceste5 pcre]#