Table 1 Role of let-7 family members as biomarkers in viral infections

HBV

Let-7c

Up

qRT-PCR

Human (serum samples of chronic hepatitis, n = 29)

99.1/98.8

[110]

HBV

Let-7c

Up

qRT-PCR

Human (serum samples of OBI, n = 11)

99.9/99.8

[110]

HBV

Let-7f

Up

Solexa

Sequencing

qRT-PCR

Human (serum samples of HCC, n = 55)

97.9/99.1

[104]

HBV

Let-7b

Up

qRT-PCR

Human (serum samples of early HCC, n = 120)

84.8/50

[273]

HBV

Let-7d-5p

Up

qRT-PCR

Human (serum samples of fibrosis, n = 14)

AUC = 0.82

[274]

HBV

Let-7c

Up

Solexa

Sequencing

qRT-PCR

Human (serum samples of chronic HBV, n = 30)

–

[104]

HBV

Let-7c

Up

qRT-PCR

Human (serum samples of chronic HBV, n = 30)

–

[104]

HBV

Let-7b-3p

Up

Microarray

Human (PBMC samples of chronic HBV, n = 16)

–

[275]

HBV

Let-7a

Up

qRT-PCR

Human (tissue samples of hepatocellular carcinoma

with active virus replication, n = 13)

/in vitro (HepG2.2.15)

–

[114]

HBV

Let-7a, b, c

Up

qRT-PCR

Human (tissue samples of chronic HBV)

–

[276]

HBV

Let-7g

Up

qRT-PCR

Human (tissue samples post-treatment with nucleos(t)ide analog in chronic HBV)

–

[277]

HBV

Let-7g

Up

qRT-PCR

Human (n = 14 tissue samples of hepatocellular carcinoma with post-treatment nucleos(t)ide analog)

–

[277]

HBV

Let-7a, b, d, g, i

Up

Microarray

In vitro (chronic hepatitis HepG2.2.15)

–

[278]

HBV

Let-7b

Down

qRT-PCR

Human (serum samples of chronic HBV with dysplastic nodule, n = 30)

84.8/50

[273]

HBV

Let-7f

Down

qRT-PCR

Human (serum samples of HCC, n = 373)

–

[279]

HBV

Let-7c

Let-7a

Down

qRT-PCR

Human (tissue samples of HCC, n = 23)

–

[280]

HBV

Let-7a

Down

qRT-PCR

Human (tissue samples of HCC, n = 20)

–

[124]

HBV

Let-7c

Down

qRT-PCR

Human (tissue samples of HCC, n = 25)

–

[281]

HBV

Let-7a

Down

qRT-PCR

Human (tissue samples of HCC, n = 20)

–

[282]

HBV

Let-7a, b, c, d

Down

Sequencing

qRT-PCR

Human (tissue samples of HCC)

–

[283]

HBV

Let-7a

Down

qRT-PCR

Human (tissue samples of HCC with less active virus replication, n = 10)

/in vitro (HepG2)

–

[114]

HBV

Let-7g

Down

qRT-PCR

Human (tissue samples of HCC with pretreatment nucleos(t)ide analog, n = 15)

–

[277]

HBV

Let-7g

Down

qRT-PCR

Human (tissue samples of pretreatment with nucleos(t)ide analog in chronic HBV, n = 27)

–

[277]

HBV

Let-7

Down

qRT-PCR

Human (tissue samples of HCC, n = 19)

/in vitro (HBx-HepG2)

-

[284]

HBV

Let-7a, c, d, e, f, g, i

Down

Microarray

qRT-PCR

In vitro (HBx-HepG2)

–

[124]

HBV

Let-7a, b, c, e, i

Down

Microarray

qRT-PCR

In vitro (HBx-SNU-182)

–

[124]

HBV

Let-7a, g

Down

Microarray

In vitro (acute hepatitis HepG2)

–

[278]

HBV

Let-7a

Down

qRT-PCR

In vitro (HepG2)

–

[120]

HBV

Let-7f

-

Microarray

qRT-PCR

Human (plasma samples of chronic HBV treated with PEG-IFN, n = 94)

–

[285]

HCV

Let-7a-1

Up

qRT-PCR

Human (serum samples of chronic HBV with liver cirrhosis, n = 20)

75/70

[134]

HCV

Let-7c, g, i

Up

qRT-PCR

Human (serum samples of HCV, n = 33)

–

[286]

HCV

(genotype 1)

Let-7g

Up

qRT-PCR

Human (tissue, serum samples of chronic HCV treated with PEG-IFN/RBV, n = 18)

–

[287]

HCV

Let-7a-5p

Down

qRT-PCR

Human (serum samples of chronic HCV with liver cirrhosis, n = 25)

92/80

[133]

HCV

Let-7a-1

Down

qRT-PCR

Human (serum samples of HCC, n = 40)

70/82.5

[134]

HCV

Let-7d-5p

Down

qRT-PCR

Human (plasma samples of chronic HCV with liver fibrosis, n = 24)

AUC = 0.79

[262]

HCV

Let-7a-5p

Down

qRT-PCR

Human (plasma samples of chronic HCV with liver fibrosis, n = 24)

AUC = 0.77

[262]

HCV

Let-7c-5p

Down

qRT-PCR

Human (plasma samples of chronic HCV with liver fibrosis, n = 24)

AUC = 0.73

[262]

HCV

Let-7a-5p

Let-7c-5p

Let-7d-5p

Down

Microarray

qRT-PCR

Human (plasma samples of chronic HCV, n = 32)

–

[262]

HCV

Let-7a, b, c, d, e, g

Down

qRT-PCR

Human (plasma samples of chronic hepatitis, n = 236)

–

[288]

HCV

Let-7a

Down

qRT-PCR

Human (serum samples of HCV, n = 97)

–

[289]

HCV

Let-7a-1

Down

qRT-PCR

Human (serum samples of chronic HCV, n = 20)

-

[134]

HCV

(genotype 1)

Let-7g

Down

qRT-PCR

Human [tissue (n = 6), serum (n = 19) samples of chronic HCV untreated with PEG-IFN/RBV]

–

[287]

HCV

(genotype 1)

Let-7g

Down

qRT-PCR

Human (tissue samples of chronic HCV, n = 18)

–

[287]

HCV (genotype 4)

Let-7a, g

Down

qRT-PCR

Human (tissue samples of chronic HCV, n = 50)

–

[290]

HCV

Let-7i

Down

qRT-PCR

Human (tissue samples of HCC, n = 22)

–

[291]

HCV

Let-7a, b, c, d, e, f, g, i

Down

qRT-PCR

Human (tissue samples of transplanted liver with HCV-related end-stage liver disease, n = 61)

–

[140]

HCV

Let-7a, b, c, d

Down

Sequencing

qRT-PCR

Human (tissue samples of HCC)

–

[283]

HCV

(genotypes

1b and 2a)

Let-7g

Down

qRT-PCR

In vitro

(Ava.5-Huh7, JFH1-Huh7.5.1)

–

[287]

HTLV-I

Let-7a

Up

qRT-PCR

In vitro (Tax-Hut102)

–

[292]

HTLV-I

Let-7a

Down

qRT-PCR

Human (blood samples of adult T-cell leukemia)

/in vitro (HBZ-C81-66, ATL-2)

–

[292]

HHV-8

Let-7a, b, c, d, e, f, g, i

Down

Microarray

Human (tissue samples of Kaposi’s sarcoma, n = 14)

–

[293]

HHV-8

Let-7a, b, e, f

Down

qRT-PCR

Human (tissue samples of Kaposi’s sarcoma, n = 4)

–

[294]

HHV-8

Let-7a, b, e, f

Down

qRT-PCR

Human (tissue samples of primary effusion lymphoma, n = 12)

–

[294]

HHV-8

Let-7a

Down

qRT-PCR

In vitro (TIVE cell)

–

[295]

HPV-16

Let-7a

Up

qRT-PCR

Human (tissue samples of precervical cancer (LSIL), n = 4)

–

[192]

HPV-16 and -18

Let-7a

Up

qRT-PCR

Human (tissue samples of precervical cancer (HSIL), n = 9)

–

[192]

HPV-16

Let-7d

Down

Microarray

qRT-PCR

Human (tissue samples of head and neck squamous cell carcinoma, n = 37)

–

[296]

HPV

Let-7b

Down

qRT-PCR

Human (serum, brush pap samples of squamous cervical cell carcinoma, n = 7)

–

[297]

HPV

Let-7g

Down

qRT-PCR

Human (tissue samples of cervical cancer, n = 20)

–

[298]

HPV

Let-7

Down

qRT-PCR

Human (tissue samples of lung cancer, n = 56)

–

[103]

EBV

Let-7d-5p

Let-7f-5p

Up

Illumina deep sequence

In vitro (SNK6 cell)

–

[299]

EBV/HSV-2

Let-7b

Up

qRT-PCR

Human (serum samples of sex workers, n = 46)

–

[300]

EBV/ HPV

Let-7b

Up

qRT-PCR

Human (serum samples of sex workers, n = 5)

–

[300]

EBV

Let-7a-5p

Let-7c-5p

Let-7d-5p

Let-7e-5p

Let-7g-5p

Down

qRT-PCR

Human (plasma samples of mononucleosis, n = 15)

–

[301]

EBV

Let-7c

Let-7e

Down

qRT-PCR

Human (tissue samples of post-transplant smooth muscle tumor, n = 5)

–

[302]

EBV

Let-7a-5p

Let-7g-5p

Down

Illumina deep sequence

In vitro (SNK6 cell)

–

[299]

EBV

Let-7a-5p

Let-7g-5p

Let-7i-5p

Down

Illumina deep sequence

In vitro (SNT16 cell)

–

[299]

EBV

Let-7a-5p

:et-7b-5p

Let-7f-5p

Down

Sequencing

qRT-PCR

In vitro (AGS)

–

[303]

EBV

Let-7b

Down

qRT-PCR

Human (serum samples of sex workers, n = 15)

–

[300]

HHV-6A

Let-7c

Down

Microarray

In vitro (NK-92 cell)

–

[304]

HHV-6B

let-7c

Down

Microarray

In vitro (NK-92 cell)

–

[304]

HSV-2

Let-7b

Up

qRT-PCR

Human (serum samples of sex workers, n = 67)

–

[300]

SARS-CoV-2

Let-7b

Up

qRT-PCR

Human (PBMC

samples of COVID-19, n = 18)

83.3/93.3

[305]

RSV

Let-7d

Up

Microarray

qRT-PCR

Human (nasal mucosa samples, n = 42)

–

[306]

RSV

Let-7b

Up

qRT-PCR

In vitro (MDDC cell)

–

[307]

RSV

Let-7c, i

Up

qRT-PCR

In vitro (NHBE cell)

–

[307]

H1N1

Let-7e

Let-7f

Up

Microarray

In vivo (mice)

–

[207]

H1N1

Let-7a, e, f, g, i

Up

NGS

In vitro (A549 cell)

–

[308]

H7N9 Avian

Let-7b, g

Up

qRT-PCR

Human (serum sample, n = 21)

–

[309]

H5N1

Let-7a, b, e, f

Up

NGS

In vitro (A549 cell)

–

[308]

H3N2

Let-7b, g, f

Up

NGS

In vitro (A549 cell)

-

[308]

H1N1

Let-7g

Down

Microarray

qRT-PCR

Human (PBMC samples, n = 299)

–

[208]

H1N1

Let-7g

Down

qRT-PCR

In vitro (A549)

–

[310]

H7N9

Let-7e

Down

qRT-PCR

Human (serum samples, n = 21)

–

[309]

H7N7

Let-7g

Down

qRT-PCR

In vitro (A549 cell)

–

[310]

H5N1

Let-7g

Down

NGS

In vitro (A549 cell)

–

[308]

H5N1 Avian

Let-7f

Down

Microarray

In vivo (macaque)

–

[311]

H3N2

Let-7a, i

Down

NGS

In vitro (A549 cell)

–

[308]

HIV-1

Let-7g-3p

Up

qRT-PCR

Human (plasma samples of acute HIV-1, n = 60)

100/100

[240]

HIV-1

Let-7g-3p

Up

qRT-PCR

Human (plasma samples of eclipse HIV-1, n = 20)

100/95.8

[240]

HIV-1

Let-7b, I, f

Down

Microarray

qRT-PCR

Human (PBMC samples of chronic HIV, n = 7)

–

[123]

HIV-1

Let-7c

Down

qRT-PCR

Human (plasma samples of naive HIV-1, n = 25)

–

[312]

HIV-1

Let-7c

Down

qRT-PCR

Human (plasma samples of HIV with ART therapy, n = 25)

–

[312]

HIV-1

Let-7c

Down

qRT-PCR

Human (plasma samples of elite controller, n = 19)

–

[312]

HIV-1

Let-7g

Down

Nanostring

TLDA

Human (PBMC samples of untreated-viremic controller, n = 6)

–

[313]

Human Metapneo

Let-7f

Up

qRT-PCR

In vitro (A549 cell)

–

[314]

West Nile

Let-7a, e, g, i

Up

qRT-PCR

In vivo (mice)

–

[315]

West Nile

Let-7c

Down

qRT-PCR

In vivo (mice)

–

[315]

Japanese encephalitis

Let-7a, b

Up

qRT-PCR

Human [n = 3 tissue samples of encephalitis/in vitro (N9)/in vivo (mice)]

–

[270]

DENV-2

Let-7e

Down

qRT-PCR

In vitro (PBMC)

–

[316]

Zika

Let-7a

Down

NGS

In vitro (neural stem cell)

–

[317]

Hendra

Let-7

Up

NGS

Horse (n = 6 blood samples)

–

[318]

Persistent Coxsackie B4

Let-7b-3p

Let-7d-3p

Let-7f-1-3p

Down

Sequencing

In vitro (PANC-1)

–

[319]