Virus

LETTER

doi:10.1038/nature11599

Resurrection of endogenous retroviruses in antibody-deficient mice
George R. Young1, Urszula Eksmond1, Rosalba Salcedo2, Lena Alexopoulou3, Jonathan P. Stoye4 & George Kassiotis1

Tcra2/2 or Tcrd2/2 mice, lacking T-cell receptor (TCR)ab and
TCRcd T cells, respectively, showed low eMLV expression (Fig. 1f). eMLV expression was similarly low in H2-A,E2/2 mice (MGI allele

Rag1–/–
60%

102

100

104
103
102
101
100

Monocytes Neutrophils

Rag1–/–

101
100
100 101 102 103 104
83A25
Ctrl antibody

100

76%

24%

Liver

101

105

Lung

102

WT
Cell counts (%)

Dendritic cells Erythroid cells 35%

51%

64%

WT

Rag1–/–

NK cells

50

0
100 101 102 103 104

83A25

h g 105

Cell counts (%)

104
103
102

Ighm–/–

Ighm–/– MD4

H2-A,E–/–

Tcra–/–

Tcrd–/–

WT

100

Rag1–/–

101

100

CD4+
T cells

CD8+
T cells

96%

B cells

95%

85%

50

0
100 101 102 103 104

WT

83A25
Ighm–/–

MD4

Spleen

107
106
105
104
103
102
101
100

Tlr7–/–

106

WT

Spleen

107

Myd88–/–

f

eMLV expression, relative to Hprt

Empty channel

103

103

WT
Rag1–/–

106

e

Splenocytes
WT

104

107

Kidney

d

1.9

105

c

Muscle

0
Log2 fold change

WT
Rag1–/–

Ileum

–1.9

106

Colon

Emv2 env
Emv2 gag
Ccl17
Ear11
Mgl2
Gm10002
Ms4a4c
Klrb1b
Cd209d

Macrophages
107

Spleen

Rag1–/–

eMLV expression, relative to Hprt

b

Macrophages
WT

eMLV expression, relative to Hprt

a

eMLV expression, relative to Hprt

The mammalian host has developed a long-standing symbiotic relationship with a considerable number of microbial species. These include the microbiota on environmental surfaces, such as the respiratory and gastrointestinal tracts1, and also endogenous retroviruses (ERVs), comprising a substantial fraction of the mammalian