Infection dynamics and persistence of hepatitis E virus on pig farms – a review

Meester, M.; Tobias, T. J.; Bouwknegt, M.; Kusters, N. E.; Stegeman, J. A.; van der Poel, W. H. M.

doi:10.1186/s40813-021-00189-z

Porcine Health Management

Table 1 HEV infection characteristics in pigs in eight inoculation studies

From: Infection dynamics and persistence of hepatitis E virus on pig farms – a review

Reference	Additional information about article	Route of infection	HEV inoculation dose	Latent period (days)	Duration of fecal shedding (days)	Period between exposure and seroconversion (days)
Satou et al. [9]	Modelled data from Halbur et al. [3]	IV	10^4.5 PI₅₀	< 7 ^a	> 7; < 27 ^a	25.0 (95% CI: 20.9–31.3)
Dähnert et al. [10]	Experiment to find minimal infectious dose of HEV in pigs	IV	9,4 * 10 ⁵ copies	range: 9–15	3/4 pigs: 7 (+ − 2.7)	17
			9,9 * 10 ⁴ copies	15	1/4 pigs: 9	23
			4,0 * 10 ³ copies	range: 17–23	no viral clearance seen ^b	27
			7,2 * 10 ³ copies	range: 17–30	no viral clearance 74–61 days after shedding started ^b	27
			6,5 * 10 ² copies	range: 27–30	no viral clearance seen, minimally 18 days ^b	37
			6,5 * 10 ¹ copies	range: 21–37	3/4 pigs: range: 11–28	27
			6,5 copies	range: 37–62	no viral clearance seen ^b	58
Bouwknegt et al. [11]	Block 1	IV	2*10⁴ PCR d.u.	3 (range: 2–7)	49 (95% CI 17–141) ^d	NA
	Block 1	Contact	Unknown	9 ^c	49 (95% CI 17–141) ^d	NA
	Block 2	IV	1*10⁴ PCR d.u.	3 (range: 2–7)	13 (95% CI 11–17) ^d	NA
	Block 2	Contact	Unknown	17 ^c	13 (95% CI 11–17) ^d	NA
Bouwknegt et al. [12]		IV	1*10⁴ PCR d.u.	3.2 (95% CI 2.0–4.3)	39.9 (95% CI 27.7–52.1)	15.7 ^e
Bouwknegt et al. [12]		Contact	Unknown	7.2 (95% CI 4.8–9.6)	23.3 (95% CI 18.7–27.9)	20.2 ^e
Casas et al. [13]	No info about PRRSV status of pigs	Oral	2*10⁵ GEs	22 / 25 ^f	NA	57 ^g
Andraud et al. [14]		Oral	1*10⁹ GEs	6.9 (95% cred. int. 5.8–7.9)	9.7 (95% cred. int. 8.2–11.3)	26.3 (95% cred. int. 23.5–29.5) ^h
Andraud et al. [14]		Contact	Unknown	7.1 (95% cred. int. 3.2–12.3)	9.7 (95% cred. int. 8.2–11.3)	26.3 (95% cred. int. 23.5–29.5) ^h
Salines et al. [15]	PRRSV coinfected. ~ Same study design as Andraud et al. 2013	Oral	1*10⁸ GEs	12.9 (95% cred. int. 12.8–14.4)	48.6 (95% cred. int. 27.9–84.6)	43.1 (95% cred. int.: 35.7–52.2)
Salines et al. [15]		Contact	Unknown	13.4 (95% cred. int. 8.6–17.1)	48.6 (95% cred. int. 27.9–84.6)	43.1 (95% cred. int.: 35.7–52.2)
Salines et al. [16]	One group of HEV only and one of HEV/PCV2 coinfected pigs	Oral (HEV only)	1*10⁷ GEs	12.3 (95% cred. int. 4.4–25.5)	NA	25.6 (95% cred. int.: 19.3–33.8)
Salines et al. [16]	One group of HEV only and one of HEV/PCV2 coinfected pigs	Oral (HEV/PCV2)	1*10⁷ GEs	11.6 (95% cred. int. 2–21.6)	NA	49.4 (95% cred. int.: 40.4–60.4)

Terms for quantifying HEV according to original article were used. In the review one term, genomic copies, is used. ^a Halbur et al. [3], Table 2. ^b Because of the long duration of latency a lot of pig couldn’t be followed up long enough to find the end of shedding period. ^c Data was censored for 20/37 pigs. ^d Based on exposure to shedding of the inoculated animals. ^e Sum of the latent period and the period between shedding and seroconversion. ^f Five animals died within 3 weeks post inoculation, with pyrexia, shivers, difficult breathing (bacterial systemic infections). Only four pigs were successfully infected of which only two shed and two others seroconverted. ^g The two seroconverted pigs had maternal antibodies. ^h Outcome was published as additional file of Salines et al. [15]

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