Vector competence and transovarial transmission of two Aedes aegypti strains to Zika virus

Figures & data

Figure 1 Schematic representation of the experimental design.

Figure 2 ZIKV infection rates of midguts (A), salivary glands (B) and ovaries (C) in two Ae. aegypti strains at different dpe to the blood meal. Eleven to fourteen mosquitoes were sampled per day. Error bars represent confidence intervals (95%).

Figure 3 Quantification of Zika viral RNA copies by real-time PCR with reverse transcription detected in midguts (A), salivary glands (B) and ovaries (C) of two Ae. aegypti strains at different dpe. Error bars represent sd.

Table 1 Positive percentages and viral titers in the brains of infant mice bitten by infectious mosquitoes

Strain	Number of mosquitoes^a	Number of mice tested	Number of positive mice	Positive percent (%)	Average virus titer of mouse brain (log10 RNA copies per mL)^b
					4d	7d	10d^*
HK	21	9	9	100.00	5.86±0.43	7.84±1.18	8.13±0.57
RL	24	9	9	100.00	6.92±1.07	8.50±0.24	9.59±0.71

Abbreviations: days, d; Zika virus, ZIKV.

a Number of blood-engorged mosquitoes removed from the cage by CO₂ anesthesia after blood-sucking. All salivary glands of these mosquitoes were ZIKV-positive.

b At 10 days post feeding, the average virus titer in the brains of infant mice bitten by RL strain females was significantly higher than that for those bitten by HK strain females.

* At 10 days post-feeding, the average titre in the brains of mice bitten by RL strain females was significantly higher than that for mice bitten by HK strain females.

Table 2 IR, MIR and viral titers of oviposited females, eggs and newly emerged females in the first gonotrophic cycle of infectious Ae.aegypti

Exp.	Strain	Number tested	Number positive	IR^a (%)	MIR^b (%)	log10 RNA copies per mL
Oviposited females^c	HK	14	14	100	—	7.48±1.31
	RL	13	13	100	—	7.70±0.61
Eggs (30 per pool)	HK	29	10	34.48	1.15	3.16±0.25
	RL	25	16	64	2.13	3.85±0.67
Salivary gland of newly emerged females^d	HK	35	6	17.14	—	5.04±0.91
	RL	31	5	16.13	—	4.25±0.35

Abbreviation: Zika virus, ZIKV.

a IR (infection rate) is calculated as the ratio of the number of ZIKV-positive individuals or pools to the total number of individuals or pools tested.

b MIR (minimum infection rate) is the ratio of the number of positive pools to the total number of individuals (eggs) tested.

c Oviposited females were mosquitoes that laid eggs in the first gonotrophic cycle. Ten to fifteen individuals were randomly removed from cages and analyzed.

d Eggs obtained from the first gonotrophic cycle were reared under standard laboratory conditions through the larvae and pupae stages until a new generation of adults emerged. The salivary glands of newly emerged females were dissected and analyzed.

Table 3 IR, MIR and viral titers of oviposited females, eggs and newly emerged females in the second gonotrophic cycle of infectious Ae.aegypti

Exp.	Strain	Number tested	Number positive	IR^a (%)	MIR^b (%)	log10 RNA copies per mL
Oviposited females^c	HK	14	14	100	—	9.48±1.12
	RL	10	10	100	—	8.05±2.77
Eggs (30 per pool)	HK	24	13	54.17	1.81	4.41±0.82
	RL	23	12	52.17	1.74	5.19±0.71
Salivary gland of newly emerged females^d	HK	47	1	2.13	—	4.77±0.00
	RL	43	1	2.33	—	3.45±0.00

Abbreviation: Zika virus, ZIKV.

a IR (infection rate) is calculated as the ratio of the number of ZIKV-positive individuals or pools to the total number of individuals or pools tested.

b MIR (minimum infection rate) is the ratio of the number of positive pools to the total number of individuals (eggs) tested.

c Oviposited females were mosquitoes that laid eggs in the second gonotrophic cycle. Ten to fifteen individuals were randomly removed from cages and analyzed.

d Eggs obtained from the second gonotrophic cycle were reared under standard laboratory conditions through the larvae and pupae stages until a new generation of adults emerged. The salivary glands of newly emerged females were dissected and analyzed.