They have different mutations and are different genetic lineages so definitely independent events

Together, we provide the requisite genetic, serological and biochemical evidence to support 33G-like be designated as a new serotype, which we have named 33H. So far, we have seen this new serotype in Mongolia and South Africa - very excited to see where else it might be!

Lastly, to confirm the lack of acetylation in the 33G-like capsule due to the loss of wciG, we conducted 1H NMR on the capsular polysaccharide, which showed that in contrast with 33G capsule, the 33G-like capsule lacks any acetyl residues.

To verify that inactivation of wciG was responsible for the change in the quellung result, we constructed an 'artificial 33G-like' by deleting wciG in a 33G strain. Indeed, this changed the quellung result from 10B and 33B to 10B and 33F.

We also conducted deep-sequencing and PCR from the nasopharyngeal swabs themselves to confirm the presence of the mutations in vivo (suggesting they were unlikely to have occurred during laboratory culture)

When we examined the capsule locus, the 33G-like capsule locus was identical to that of 33G except for one difference - all the 33G-like isolates had frameshift mutations in a capsule gene called wciG, which encodes an acetyltransferase.

During our pneumonia surveillance program in adults in Mongolia, we isolated pneumococcal variants in nasopharyngeal swabs that resembled serotype 33G. Where 33G yields the serotype result of 10B and 33B by quellung, these variants (which we called 33G-like) would give the result of 10B and 33F.