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Published Date: 2019-03-03 17:35:19
Subject: PRO/AH/EDR> MERS-CoV (29): animal reservoir, camel, vaccine trial
Archive Number: 20190303.6347273
MERS-COV (29): ANIMAL RESERVOIR, CAMEL, VACCINE TRIAL
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Date: Sat 2 Mar 2019
Source: Viruses 2019 11 (3):212 [summarized, edited]
https://www.mdpi.com/1999-4915/11/3/212


Citation: DR Adney, L Wang, N van Doremalen, W Shi, Y Zhang, WP Kong, et al. Efficacy of an adjuvanted Middle East respiratory syndrome Coronavirus spike protein vaccine in dromedary camels and alpacas. Viruses 2019; 11(3): 212; doi:10.3390/v11030212.

Abstract
MERS-CoV is present in dromedary camels throughout the Middle East and Africa. Dromedary camels are the primary zoonotic reservoir for human infections. Interruption of the zoonotic transmission chain from camels to humans, therefore, may be an effective strategy to control the ongoing MERS-CoV outbreak. Here we show that vaccination with an adjuvanted MERS-CoV Spike protein subunit vaccine confers complete protection from MERS-CoV disease in alpaca and results in reduced and delayed viral shedding in the upper airways of dromedary camels. Protection in alpaca correlates with high serum neutralizing antibody titers. Lower titers of serum neutralizing antibodies correlate with delayed and significantly reduced shedding in the nasal turbinates of dromedary camels. Together, these data indicate that induction of robust neutralizing humoral immune responses by vaccination of naive animals reduces shedding that potentially could diminish the risk of zoonotic transmission.

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[In the discussion chapter, the authors indicate that after vaccination, low neutralizing antibody titers were detected in the upper respiratory tract. Vaccine platforms aimed specifically at inducing high levels of mucosal immunity or those that induce humoral as well as cellular immunity may be required for complete protection. The response to vaccination in dromedary camels varies widely, as was demonstrated in the study by the fact that one out of the 3 camels in the vaccination group did not respond to vaccination at all. The trial involved alpacas and dromedaries born in the US; intranasal challenge with MERS-CoV yielded distinctly different outcomes in the alpaca compared to dromedary camels. Though alpacas are easier to get, future vaccination trials deserve to be performed on dromedary camels.

Although the origins and transmission of MERS are poorly understood, since the emergence of the disease in 2012, the dromedary camel has remained as the one documented source of human zoonotic infection. There is considerable circumstantial evidence supporting camel-to-human transmission, including evidence of camels and humans becoming infected with an identical MERS-CoV. Among the 1125 MERS-CoV cases reported to WHO between 1 Jan 2015 and 13 Apr 2018, 30.9 per cent were primary cases (the 1st known human case in a potential or putative chain of transmission). Among primary cases, 191 (54.9 per cent) reported direct or indirect contact with dromedaries, 164 (47.1 per cent) reported direct, physical contact with dromedaries, and 155 (44.5 per cent) reported contact with products derived from dromedaries, namely unpasteurized camel milk.

One of the measures to interrupt zoonotic transmission of MERS could be vaccination of dromedaries and/or humans. Vaccination of dromedaries should target mainly the offspring, regarded to be the main source of virus dissemination. The above report addresses one of several vaccination trials performed in recent years.

A recent review paper by Chinese researchers (ref 1) included vaccination (in humans and animals) among its topics. It was indicated that among all the functional/non-functional structural proteins of MERS-CoV (similar to SARS-CoV), the S protein is the principal antigenic component that induces antibodies to block virus-binding, stimulate host immune responses, fuse or neutralize antibodies and/or protect the immune system against virus infection. Therefore, the S protein has been selected as a significant target for the development of vaccines.

The authors review 5 MERS-CoV vaccine strategies, their development and advantages/disadvantages.
1. Inactivated virus vaccines
2. Live-attenuated virus vaccines
3. Viral vector vaccines
4. Subunit vaccines
5. DNA vaccines.

For each strategy, the process of production, references, advantages and disadvantages are presented (see table 3 in ref 1).

There are still no commercial vaccines available against MERS-CoV. To vaccinate camels, animals in which MERS-CoV infection is manifested by a mild or subclinical disease, the MERS vaccine -- when becoming certified and available -- should preferably be combined with vaccine(s) protecting against significant camel disease (for example, camel pox) in order to safeguard the cooperation of the camel owners.

Reference:
1. Z Song, Y Xu, L Bao, L Zhang, P Yu, Y Qu, et al. From SARS to MERS, thrusting coronaviruses into the spotlight. Viruses 2019; 11(1): 59; https://doi.org/10.3390/v11010059; https://www.mdpi.com/1999-4915/11/1/59. - Mod.AS]

See Also

MERS-CoV (02): Kenya, animal reservoir, camel, serosurveillance, genotyping 20190105.6240916
2018
---
MERS-CoV (48): Saudi Arabia (MK) animal reservoir, camel, spread, OIE 20181205.6182531
MERS-CoV (26): Saudi Arabia, abattoir workers (Nigeria), primary camel exposure 20180818.5972601
MERS-CoV (14): Israel, animal reservoir, camelids 20180506.5787312
2017
---
MERS-CoV (66): Burkina Faso, animal reservoir, camels, FAO, RFI 20171029.5411777
MERS-CoV (64): Saudi Arabia, animal reservoir, human, camel milk 20171012.5375933
MERS-CoV (62): animal reservoir, camels, FAO, OIE, WHO 20171002.5354608
MERS-CoV (40): animal reservoir, camels, review, FAO 20170619.5115999
MERS-CoV (29): Qatar, animal reservoir, camels 20170527.5066519
MERS-CoV (28): Qatar, Saudi Arabia (HA) 20170524.5059234
MERS-CoV (23): Saudi Arabia (AS) animal reservoir, human contact, OIE, RFI 20170421.4986081
MERS-CoV (21): Egypt, animal reservoir, camel, ex Sudan, control, RFI 20170405.4948727
MERS-CoV (18): Africa, animal reservoir, camels, 2015, research 20170331.4939980
2016
---
MERS-CoV (87): Jordan, animal reservoir, camelids, OIE 20160802.4385317
MERS-CoV (66): Saudi Arabia, animal reservoir, camelids, OIE, RFI 20160618.4294807
MERS-CoV (59): animal reservoir, review 20160610.4275921
MERS-CoV (40): Egypt, animal reservoir, camel, ex Sudan, susp. 20160316.4097730
MERS CoV (21): Saudi Arabia, animal reservoir, camel, comment 20160216.4023772
MERS CoV (19): Saudi Arabia, animal reservoir, camel, prevention, RFI 20160204.3995194
MERS-CoV (18): Saudi Arabia, animal reservoir, camel, vaccination, comment 20160203.3990284
MERS-CoV (16): Saudi Arabia (MK) animal reservoir, OIE, RFI 20160201.3985175
MERS-CoV (11): Saudi Arabia, animal reservoir, camel, vaccination, comment 20160126.3966528
MERS-CoV (09): Saudi Arabia, animal reservoir, camel, vaccination considered 20160125.3963370
2015
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MERS-CoV (163): Saudi Arabia, animal reservoir, camel, research, vaccine 20151219.3873486
MERS-CoV (155): animal reservoir, camel, research, RFI 20151110.3781744
MERS-CoV (154): Saudi Arabia, animal reservoir, camel, case control 20151105.3768115
MERS-CoV (146): Saudi Arabia (Hufoof) new cases, vaccine 20151020.3730169
MERS-CoV (143): Kenya, animal reservoir, camel, serosurveillance 20151017.3722887
MERS-CoV (141): Saudi Arabia, animal reservoir, camel debated, RFI 20151016.3720479
MERS-CoV (131): Saudi Arabia, animal reservoir, camels, Hajj, RFI 20150914.3643612
MERS-CoV (130): Saudi Arabia, animal reservoir, camels, Hajj 20150912.3641457
MERS-CoV (114): Saudi Arabia, animal reservoir, camels, Hajj 20150823.3597358
MERS-CoV (113): Saudi Arabia, experimental vaccine, inc. cases 20150822.3596073
MERS-CoV (104): Saudi Arabia, animal reservoir, camel debate 20150810.3569207
MERS-CoV (63): animal reservoir, bat 20150612.3432410
MERS-CoV (48): UAE (Dubai) animal reservoir, camel 20150527.3386738
MERS-CoV (29): UAE (Dubai) animal reservoir, camel 20150303.3204214
MERS-CoV (27): Saudi Arabia, animal reservoir, camel 20150302.3200502
MERS-CoV (12): animal reservoir, camels debated, case-control study, RFI 20150122.3109335
MERS-CoV (09): Saudi Arabia, animal reservoir, camels debated 20150117.3098294
2014
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MERS-CoV (67): Iran (SB) animal reservoir, camel, ex Pakistan, RFI 20141219.3039497
MERS-CoV (49): Iran (SB), animal reservoir, camel conf, OIE 20141029.2912385
MERS-CoV (46): animal reservoir, camel, S.Arabia, vaccination, Iran susp, RFI 20141027.2904032
MERS-CoV (40): animal reservoir, camel, milk susp, RFI 20141022.2889778
MERS-CoV (24): animal reservoir, camel, experimental infection 20140929.2813981
MERS-CoV (09): animal reservoir, update, OIE, WHO 20140818.2700879
MERS-CoV (07): animal reservoir, camel, bat 20140720.2623848
MERS-CoV - Eastern Mediterranean (79): Qatar (OIE) Kuwait (susp) animal res, RFI 20140611.2533756
MERS-CoV - Eastern Mediterranean (77): S Arabia, Qatar, animal res, control, RFI 20140607.2525113
MERS-CoV - Eastern Mediterranean (75): Animal res, camel, zoonotic aspects 20140604.2518134
MERS-CoV - Eastern Mediterranean (66): Oman (SH), camel conf, OIE 20140523.2493556
MERS-CoV - Eastern Mediterranean (62): Saudi Arabia, Africa, animal res., camel 20140517.2478989
MERS-CoV - Eastern Mediterranean (46): Saudi Arabia, animal reservoir, camel 20140430.2440228
MERS-CoV - Eastern Mediterranean (41): Oman, animal reservoir, camel 20140426.2432011
MERS-CoV - Eastern Mediterranean (39): Qatar (RY) animal res., camel, OIE 20140424.2426491
MERS-CoV - Eastern Mediterranean (34): animal reservoir, camel, Saudi Arabia, RFI 20140419.2414479
MERS-CoV - Eastern Mediterranean (19): Saudi Arabia, UAE, WHO 20140325.2356854
MERS-CoV - Eastern Mediterranean (10): camel, Sudan, Ethiopia 20140228.2307254
MERS-CoV - Eastern Mediterranean (09): animal reservoir, camel, Saudi Arabia 20140227.2303420
MERS-CoV - Eastern Mediterranean (02): animal reservoir, camel, UAE, serology 20140104.2151807
2013
---
MERS-CoV - Eastern Mediterranean (106): animal reservoir, camel, Qatar, OIE 20131231.2145606
MERS-CoV - Eastern Mediterranean (101): animal reservoir, camel, goat 20131217.2120936
MERS-CoV - Eastern Mediterranean (98): animal reserv/camel, Jordan, Saudi Arabia 20131213.2114362
MERS-CoV - Eastern Mediterranean (95): animal reservoir, camel, Qatar 20131129.2082942
MERS-CoV - Eastern Mediterranean (94): UAE (Abu Dhabi), Qatar 20131129.2082330
MERS-CoV - Eastern Mediterranean (93): animal res., camel conf, Qatar (RY) OIE 20131129.2082115
MERS-CoV - Eastern Mediterranean (87): animal res. camel susp. precautions 20131113.2053932
MERS-CoV - Eastern Mediterranean (85): animal reservoir, camel, susp. official 20131112.2051424
MERS-CoV - Eastern Mediterranean (83): animal reservoir, camel, susp., RFI 20131112.2050868
MERS-CoV - Eastern Mediterranean (75): role of bats in emergence, Saudi Arabia new cases 20131011.1996687
MERS-CoV - Eastern Mediterranean (68): animal reservoir, camel, research 20130907.1929762
MERS-CoV - Eastern Mediterranean (66): animal reservoir, discussion 20130904.1922998
MERS-CoV - Eastern Mediterranean (61): animal reservoir, bat, comment 20130828.1907567
MERS-CoV - Eastern Mediterranean (57): animal reservoir, bats 20130822.1895035
MERS-CoV - Eastern Mediterranean (53): animal reservoir, serology, FAO 20130811.1875301
MERS-CoV - Eastern Mediterranean (52): animal reservoir, research, serology 20130809.1872008
MERS-CoV - Eastern Mediterranean (50): animal reservoir, OIE 20130727.1849047
MERS-CoV - Eastern Mediterranean (48): animal reservoir, bat susp. 20130725.1844412
MERS-CoV - Eastern Mediterranean (39): animal reservoir, research 20130706.1810714
MERS-CoV - Eastern Mediterranean (25): Saudi Arabia, genome 20130612.1768944
MERS-CoV - Eastern Mediterranean (10): animal reservoir, research 20130524.1735984
MERS-CoV - Eastern Mediterranean (03): animal reservoir, RFI 20130519.1723544
MERS-CoV - Eastern Mediterranean (02): WHO summary, ECDC risk assessments 20130518.1721873
Novel coronavirus - Eastern Mediterranean (15): camel exposure 20130405.1623188
Novel coronavirus - Eastern Mediterranean: bat reservoir 20130122.1508656
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