Transmission network and phylogenetic analysis reveal older male-centered transmission of CRF01_AE and CRF07_BC in Guangxi, China

Figures & data

Table 1. Socio-demographic characteristics of HIV patients in Guangxi, 2017–2018.

Variables	Study population (n = 484)		Patients in transmission cluster (n = 267)		Patients in transmission cluster containing RHI (n = 157)		Patients in large transmission cluster (n = 134)		Patients with high linkage (n = 69)
	n	%	n	%	n	%	n	%	n	%
Age
<30 years old	50	10.4	20	7.5	8	5.1	7	5.2	4	5.8
30–49 years old	233	48.1	114	42.7	71	45.2	64	47.8	27	39.1
≥50 years old	201	41.5	133	49.8	78	49.7	63	47.0	38	55.1
Gender
Male	352	72.7	192	71.9	115	73.2	100	74.6	52	75.4
Female	132	27.3	75	28.1	42	26.8	34	25.4	17	24.6
Ethnicity
Han	439	90.7	249	93.3	148	94.3	128	95.5	64	92.8
Zhuang	45	9.3	18	6.7	9	5.7	6	4.5	5	7.2
Education
≤6 years	264	54.6	161	59.6	94	59.9	80	59.7	42	60.9
7–9 years	170	35.1	91	34.1	53	33.8	46	34.3	24	34.8
≥10 years	50	10.3	17	6.3	10	6.3	8	6.0	3	4.3
Occupation
Farmer	335	69.2	189	70.8	113	72.0	100	74.6	47	68.1
Others	149	30.8	78	29.2	44	28.0	34	25.4	22	31.9
Marital Status
Unmarried	117	24.2	61	22.8	38	24.2	35	26.1	14	20.3
Married/Cohabiting	278	57.4	157	58.8	96	61.1	79	59.0	43	62.3
Divorced/Widowed	89	18.4	49	18.4	23	14.7	20	14.9	12	17.4
Transmission Route
HETs	388	80.2	220	82.4	124	79.0	102	76.1	53	76.8
IDUs	84	17.3	43	16.1	30	19.1	29	21.6	13	18.8
Others	12	2.5	4	1.5	3	1.9	3	2.2	3	4.4
HIV Subtype
CRF01_AE	257	53.1	145	54.3	71	45.3	51	38.1	42	60.9
CRF08_BC	162	33.5	87	32.6	63	40.1	63	47.0	12	17.4
CRF07_BC	48	9.9	29	10.9	23	14.6	20	14.9	15	21.7
Others	17	3.5	6	2.2	0	0.0	0	0.0	0	0.0
Time from Diagnosis to Sampling
≤2 years	339	70.0	196	73.4	114	72.6	93	69.4	50	72.5
>2 years	145	30.0	71	26.6	43	27.4	41	30.6	19	27.5
Infection Status
RHI	25	5.2	25	9.4	25	15.9	12	9.0	13	18.8
CHI	459	94.8	242	90.6	132	84.1	122	91.0	56	81.2
High-risk Sexual Behaviour
Yes	108	22.3	62	23.2	40	25.5	34	25.4	15	21.7
No	376	77.7	205	76.8	117	74.5	100	74.6	54	78.3
History of Intravenous Drug Use
Yes	103	21.3	53	19.9	37	23.6	35	26.1	15	21.7
No	381	78.7	214	80.1	120	76.4	99	73.9	54	78.3
Current Place of Residence
Lingshan	192	39.7	102	38.2	71	45.3	67	50.0	29	42.2
Qinbei	106	21.9	63	23.6	31	19.7	28	20.9	11	15.9
Qinnan	104	21.5	56	21.0	36	22.9	27	20.1	23	33.3
Pubei	60	12.4	41	15.4	17	10.8	11	8.2	5	7.2
Outside Qinzhou	22	4.5	5	1.8	2	1.3	1	0.8	1	1.4

Other genotypes include subtype B, C, G, CRF55_01B and unique recombinant form. Other transmission routes include mem who have sex with men (MSM), blood transmission (BLD) and unknown. Abbreviations: ART, antiretroviral therapy; IDUs, intravenous drug users; HETs, heterosexuals; CRF, circulating recombinant form; RHI, recent HIV infection; CHI, chronic HIV infection.

Figure 1. HIV Transmission network in Guangxi. Nodes indicate HIV patients or sequences. The size of a node is proportional to its degree. Edges (i.e. links) represent genetic linkage (≤0.018 substitutions/site). Colours indicate different age groups in (a) and HIV subtypes in (b). Shapes indicate gender in (a) and different transmission routes in (b). Other genotypes include subtype B, C, G, CRF55_01B and unique recombinant form. Other transmission routes include mem who have sex with men (MSM), blood transmission (BLD), and unknown.

Figure 2. Large transmission clusters. Nodes indicate patients or sequences. The size of a node is proportional to its degree. Edges (i.e. links) represent genetic linkage (≤0.018 substitutions/site). Colours indicate different age groups. Shapes indicate different transmission routes. Nodes with degree ≥15 (i.e. individuals at high risk of HIV transmission) are circled with black dashed lines and indicated by black arrows, except for one node in cluster five with degree  = 10.

Figure 3. Transmission clusters containing RHI. Nodes indicate patients or sequences. The size of a node is proportional to its degree. Edges (i.e. links) represent genetic linkage (≤0.018 substitutions/site). Colours indicate different age groups. Shapes indicate HIV infection status. Recently infected individuals are circled with black dashed lines and indicated by black arrows. Clusters are arranged by different HIV subtypes. Abbreviations: CRF, circulating recombinant form; CHI, chronic HIV infection; RHI, recent HIV infection.

Figure 4. HIV migration events. Well-supported virus dispersal events among age-gender subgroups of (a) CRF01_AE, (b) CRF08_BC, and (c) CRF07_BC. Only results with a Bayes factor (BF) ≥ 3 and posterior probability support ≥0.9 are presented. Arrows indicate the direction of HIV migration events. The colours were chosen to visually distinguish the different level of BF values. Abbreviations: OF, older female; OM, older male; YF, younger female; YM, younger male.

Table 2. Factors associated with clustering among HIV patients in Guangxi, 2017–2018.

Variables	Study Population (n)	Patient in transmission cluster [n (%)]	COR (95% CI)	P value	AOR (95% CI)	P value
Age
<30 years old	50	20 (40.0)	1		1
30–49 years old	233	114 (48.9)	1.432 (0.772–2.675)	0.253	1.258 (0.600–2.637)	0.544
≥50 years old	201	133 (66.2)	2.934 (1.552–5.546)	0.001	2.303 (1.012–5.241)	0.047
Gender
Male	352	192 (54.5)	1		1
Female	132	75 (56.8)	1.096 (0.733–1.641)	0.654	1.401 (0.844–2.325)	0.192
Ethnicity
Zhuang	45	18 (40.0)	1		1
Han	439	249 (56.7)	1.966 (1.052–3.675)	0.034	3.089 (1.381–6.909)	0.006
Education
≥10 years	50	17 (34.0)	1		1
7–9 years	170	91 (53.5)	2.236 (1.158–4.318)	0.017	2.311 (1.099–4.858)	0.027
≤6 years	264	161 (61.0)	2.939 (1.558–5.546)	0.001	2.508 (1.190–5.287)	0.016
Occupation
Others	149	78 (52.3)	1		1
Farmer	335	189 (56.4)	1.178 (0.800–1.736)	0.406	0.872 (0.540–1.407)	0.574
Marital Status
Unmarried	117	61 (52.1)	1		1
Married/Cohabiting	278	157 (56.5)	1.191 (0.772–1.837)	0.429	0.733 (0.423–1.273)	0.270
Divorced/Widowed	89	49 (55.1)	1.125 (0.647–1.955)	0.677	0.662 (0.334–1.315)	0.239
Transmission Route
Others	12	4 (33.3)	1		1
IDUs	84	43 (51.2)	2.098 (0.587–7.501)	0.255	1.486 (0.307–7.199)	0.623
HETs	388	220 (56.7)	2.619 (0.776–8.844)	0.121	1.633 (0.426–6.266)	0.475
HIV Subtype
CRF01_AE	257	145 (56.4)	1		1
CRF08_BC	162	87 (53.7)	0.896 (0.604–1.330)	0.586	1.031 (0.628–1.693)	0.905
CRF07_BC	48	29 (60.4)	1.179 (0.629–2.211)	0.608	1.305 (0.647–2.633)	0.457
Others	17	6 (35.3)	0.421 (0.151–1.174)	0.098	0.545 (0.183–1.626)	0.276
Time from Diagnosis to Sampling
>2 years	145	71 (49.0)	1		1
≤2 years	339	196 (57.8)	1.429 (0.967–2.111)	0.073	1.244 (0.719–2.152)	0.434
Infection Status
CHI	459	242 (52.7)	1		1
RHI	25	25 (100.0)	1448586946	0.998	1214111167	0.998
High-risk Sexual Behaviour
No	376	205 (54.5)	1		1
Yes	108	62 (57.4)	1.124 (0.730–1.732)	0.595	1.192 (0.724–1.963)	0.490
History of Intravenous Drug Use
No	381	214 (56.2)	1		1
Yes	103	53 (51.5)	0.827 (0.535–1.280)	0.394	1.441 (0.535–3.881)	0.469
Current Place of Residence
Pubei	60	41 (68.3)	1		1
Lingshan	192	102 (53.1)	0.525 (0.284–0.970)	0.040	0.512 (0.253–1.035)	0.062
Qinbei	106	63 (59.4)	0.679 (0.348–1.324)	0.256	0.874 (0.403–1.895)	0.733
Qinnan	104	56 (53.8)	0.541 (0.278–1.053)	0.071	0.438 (0.210–0.915)	0.028
Outside Qinzhou	22	5 (22.7)	0.136 (0.044–0.424)	0.001	0.137 (0.041–0.452)	0.001

Other genotypes include subtype B, C, G, CRF55_01B and unique recombinant form. Other transmission routes include mem who have sex with men (MSM), blood transmission (BLD) and unknown. Statistically significant P values are indicated in bold. Abbreviations: ART, antiretroviral therapy; COR, crude odds ratios; AOR, adjusted odds ratios; CI, confidence intervals; IDUs, intravenous drug users; HETs, heterosexuals; CRF, circulating recombinant form; RHI, recent HIV infection; CHI, chronic HIV infection.

Table 3. Factors associated with high linkage (i.e. degree ≥7) among clustered individuals within networks.

Variables	Patients in transmission cluster (n)	Patients with high linkage [n (%)]	COR (95% CI)	P value	AOR (95% CI)	P value
Age
<30 years old	20	4 (20.0)	1		1
30–49 years old	114	27 (23.7)	1.241 (0.382–4.030)	0.719	1.119 (0.260–4.810)	0.880
≥50 years old	133	38 (28.6)	1.600 (0.502–5.096)	0.426	1.241 (0.265–5.817)	0.784
Gender
Male	192	52 (27.1)	1		1
Female	75	17 (22.7)	0.789 (0.421–1.478)	0.459	0.522 (0.230–1.180)	0.118
Ethnicity
Zhuang	18	5 (27.8)	1		1
Han	249	64 (25.7)	0.899 (0.309–2.622)	0.846	0.570 (0.146–2.225)	0.419
Education
≥10 years	17	3 (17.6)	1		1
7–9 years	91	24 (26.4)	1.672 (0.442–6.329)	0.449	1.532 (0.295–7.967)	0.612
≤6 years	161	42 (26.1)	1.675 (0.458–6.121)	0.435	1.481 (0.294–7.459)	0.634
Occupation
Others	78	22 (28.2)	1		1
Farmer	189	47 (24.9)	0.843 (0.465–1.525)	0.571	0.965 (0.445–2.096)	0.929
Marital Status
Unmarried	61	14 (23.0)	1		1
Married/Cohabiting	157	43 (27.4)	1.266 (0.634–2.530)	0.504	1.559 (0.613–3.964)	0.351
Divorced/Widowed	49	12 (24.5)	1.089 (0.450–2.633)	0.850	1.271 (0.398–4.053)	0.686
Transmission Route
Others	4	3 (75.0)	1		1
IDUs	43	13 (30.2)	0.144 (0.014–1.522)	0.107	0.164 (0.005–5.552)	0.315
HETs	220	53 (24.1)	0.106 (0.011–1.039)	0.054	0.076 (0.004–1.360)	0.080
HIV Subtype
CRF01_AE	145	42 (29.0)	1		1
CRF08_BC	87	12 (13.8)	0.392 (0.193–0.796)	0.010	0.167 (0.061–0.459)	0.001
CRF07_BC	29	15 (51.7)	2.628 (1.167–5.918)	0.020	3.635 (1.384–9.548)	0.009
Others	6	0 (0.0)	0 (0)	0.999	0 (0)	0.999
Time from Diagnosis to Sampling
>2 years	71	19 (26.8)	1		1
≤2 years	196	50 (25.5)	0.937 (0.506–1.735)	0.837	0.965 (0.349–2.668)	0.946
Infection Status
CHI	242	56 (23.1)	1		1
RHI	25	13 (52.0)	3.598 (1.554–8.331)	0.003	3.468 (1.315–9.146)	0.012
High-risk Sexual Behavior
No	205	54 (26.3)	1		1
Yes	62	15 (24.2)	0.892 (0.462–1.725)	0.735	0.836 (0.376–1.859)	0.660
History of Intravenous Drug Use
No	214	54 (25.2)	1		1
Yes	53	15 (28.3)	1.170 (0.597–2.292)	0.648	1.446 (0.209–9.987)	0.709
Current Place of Residence
Pubei	41	5 (12.2)	1		1
Lingshan	102	29 (28.4)	2.860 (1.022–8.009)	0.045	7.170 (1.999–25.721)	0.003
Qinbei	63	11 (17.5)	1.523 (0.487–4.759)	0.469	1.806 (0.492–6.625)	0.373
Qinnan	56	23 (41.1)	5.018 (1.710–14.722)	0.003	4.824 (1.476–15.762)	0.009
Outside Qinzhou	5	1 (20.0)	1.800 (0.166–19.500)	0.629	1.501 (0.083–27.284)	0.784

Other genotypes include subtype B, C, G, CRF55_01B and unique recombinant form. Other transmission routes include mem who have sex with men (MSM), blood transmission (BLD) and unknown. Statistically significant P values are indicated in bold. Abbreviations: COR, crude odds ratios; AOR, adjusted odds ratios; CI, confidence intervals; IDUs, intravenous drug users; HETs, heterosexuals; CRF, circulating recombinant form; RHI, recent HIV infection; CHI, chronic HIV infection.

Table 4. Differences between RHI and CHI patients among clustered individuals within networks

Variables	Patients in transmission cluster (n)	RHI patients		CHI patients		χ^2	P value
		n	%	n	%
Age						5.431	0.020
<50 years old	134	7	28.0	127	52.5
≥50 years old	133	18	72.0	115	47.5
Gender						0.854	0.355
Male	192	16	64.0	176	72.7
Female	75	9	36.0	66	27.3
Ethnicity						2.311	0.128*
Han	249	21	84.0	228	94.2
Zhuang	18	4	16.0	14	5.8
Education						2.873	0.646
≤6 years	161	17	68.0	142	58.7
7–9 years	91	7	28.0	84	34.7
≥10 years	17	1	4.0	16	6.6
Occupation						1.552	0.213
Farmer	189	15	60.0	174	71.9
Others	78	10	40.0	68	28.1
Marital Status						1.858	0.395
Unmarried	61	3	12.0	58	24.0
Married/Cohabiting	157	17	68.0	140	57.8
Divorced/Widowed	49	5	20.0	44	18.2
Transmission Route						6.500	0.036**
HETs	220	25	100.0	195	80.6
IDUs	43	0	0.0	43	17.8
Others	4	0	0.0	4	1.6
HIV Subtype						10.222	0.012**
CRF01_AE	145	21	84.0	124	51.2
CRF08_BC	87	2	8.0	85	35.1
CRF07_BC	29	2	8.0	27	11.2
Others	6	0	0.0	6	2.5
Time from Diagnosis to Sampling						9.992	0.002
≤2 years	196	25	100.0	171	70.7
>2 years	71	0	0.0	71	29.3
High-risk Sexual Behavior						1.192	0.275
Yes	62	8	32.0	54	22.3
No	205	17	68.0	188	77.7
History of Intravenous Drug Use						5.524	0.019*
Yes	53	0	0.0	53	21.9
No	214	25	100.0	189	78.1
Current Place of Residence						10.370	0.027**
Lingshan	102	5	20.0	97	40.1
Qinbei	63	5	20.0	58	24.0
Qinnan	56	12	48.0	44	18.2
Pubei	41	3	12.0	38	15.7
Outside Qinzhou	5	0	0.0	5	2.0

Other genotypes include subtype B, C, G, CRF55_01B and unique recombinant form. Other transmission routes include mem who have sex with men (MSM), blood transmission (BLD) and unknown. * indicates Yates’s correction for continuity. ** indicates Fisher’s exact test. Statistically significant P values are indicated in bold. Abbreviations: IDUs, intravenous drug users; HETs, heterosexuals; CRF, circulating recombinant form; RHI, recent HIV infection; CHI, chronic HIV infection.