limit which serves as a lower limit for protein homology.
Boughalmi et al.
12 described a new member of the family
Mimiviridae from the medicinal leech, Hirudo medicinalis,
called Hirudovirus, with a genome represented by two
scaffolds, 1. 16 Mbp and 25. 7 Kbp long, each.
13 This species
has 998 ORFs, 47% of which had orthologs in other species.
The number of common genes, JCVs with the previous four
species can be seen in table 2. Hirudovirus is most similar
to Mimivirus and Mamavirus, possibly only a new strain.
With the inclusion of this new species, the average JCV
increases to 0.6.
Though Cafeteria roenbergensis virus is considered to be
a distant member of the Mimiviridae family, Yoosuf et al.
found ≤ 5% of its genes to be in common with two strains of
Mimiviridae, the Terra1 and Terra2 viruses. Indeed, when
compared to the four members of this group, we see that
the average JCV is 0.03, which is very low, thus we should
exclude Cafeteria roenbergensis virus from this group.
The Poxviridae apobaramin
The Poxviridae are another group of highly variable
NCLDVs, similar to Phycodnaviridae, made up of
two subfamilies, and also of several genera. The
Entomopoxvirinae (EPV) infect insect hosts, whereas the
Chordopoxvirinae (ChPV) infect vertebrates. While these
NCLDVs infect a wide range of hosts, each species infects
a narrow range of hosts. Genetically, these organisms have
a genome size range of 133–360 kbp, and from 133–328
genes, and also vary in AT%. Cluster 4 is comprised of
Chordopoxvirinae species, whereas cluster 5 is made up of
Entomopoxvirus species. Lefkowitz et al.
15 also did pair-
wise sequence comparison (PASC) on DNA polymerase for
all Poxviridae species, and found that comparisons between
the two subfamilies yielded a sequence identity of 23–31%,
which is below the protein homology threshold of 40%.
This is strong evidence that the ChPVs and the EPVs belong
to different baramins. Species in separate EPV genera also
“show almost as much divergence between themselves as
they do with ChPVs”.
Marseilleviridae consists of NCLDVs discovered in water
sources in France, Tunisia16 and Senegal.
17 These species
form a compact baramin, with the majority of their genomes
being collinear with each other, and also share a large
number of orthologous proteins. Even their GC% content
ranges only between 43–45%, which reflects a very similar
genomic makeup. Approximately two thirds of their
genes are ORFans.
16, 18 An analysis of six Marseillevirus
species showed that the pan-genome contained a total
of 608 genes of which 233 genes were common to all
six species. The genomes of these organisms, which are
particularly stable despite varying between distinctly
different ecological niches, further support the stability
of baranomes (the created genome within a specific
kind). Recently, the Port-Miou virus was discovered,
which is 99% similar to Lausannevirus, exhibiting only
one indel per 1,000 bp.
Species Number of common genes JCV
Acanthamoeba castellanii mamavirus 975 0.99
Acanthamoeba polyphaga mimivirus 982 0.69
Acanthamoeba polyphaga moumouvirus 772 0.96
Megavirus chiliensis 835 0.65
Table 2. Jaccard Coefficient Values between Hirudovirus and members of the
Figure 2. Baraminological tree of Ostreococcus, Micromonas, and Bathycoccus species