Coronavirus – Credit CDC PHIL
# 7821
A dispatch, published today in the CDC’s EID Journal, describes the search for MERS coronavirus neutralizing antibodies – which would suggest prior exposure to the virus - in blood samples drawn from two groups. Group one, 158 children hospitalized with respiratory infections in Saudi Arabia’s Eastern Province between May 2010–May 2011, and Group Two from 110 Adults at the same hospital who donated blood in December of 2012.
The results - obtained using a recently developed serological test employing a lentiviral vector system bearing the spike protein from the MERS virus - were that none of the 268 blood and serum samples tested positive for neutralizing antibodies to the MERS coronavirus.
First a link to the dispatch, and some excerpts, then I’ll return with a bit more.
Lack of MERS Coronavirus Neutralizing Antibodies in Humans, Eastern Province, Saudi Arabia
Stefanie Gierer1, Heike Hofmann-Winkler1, Waleed H. Albuali, Stephanie Bertram, Abdullah M. Al-Rubaish, Abdullah A. Yousef, Awatif N. Al-Nafaie, Amein K. Al-Ali, Obeid E. Obeid, Khaled R. Alkharsah, and Stefan Pöhlmann1
Abstract
We used a lentiviral vector bearing the viral spike protein to detect neutralizing antibodies against Middle East respiratory syndrome coronavirus (MERS-CoV) in persons from the Eastern Province of Saudi Arabia. None of the 268 samples tested displayed neutralizing activity, which suggests that MERS-CoV infections in humans are infrequent in this province.
The emergence of the Middle East respiratory syndrome coronavirus (MERS-CoV, formerly termed EMC coronavirus [1]) could pose a serious threat to public health (2). As of September 2013, a total of 108 laboratory-confirmed infections (with 50 deaths) caused by MERS-CoV have been reported to the World Health Organization (WHO), most from Saudi Arabia (3), but data are limited on MERS-CoV seroprevalence in humans (4).
<SNIP>
Conclusions
Our results suggest that the estimated MERS-CoV seroprevalence in the area served by King Fahd Hospital was <2.3% in children during 2010–2011 and <3.3% in male adults in 2012 (upper limits of the 95% CIs for 0/158 and 0/110, respectively, by Fisher exact test). Our analysis of samples from children might have underestimated seroprevalence because if they were hospitalized for MERS-CoV infection, a virus-specific antibody response might have developed after sample collection. Moreover, although infection of young children has been reported (8), the average age of MERS patients is 50 years. Our findings using samples from adult men argue against the extensive spread of MERS-CoV within this group in the Eastern Province of Saudi Arabia during 2012, which is noteworthy given recent reports of asymptomatic MERS-CoV infections (9,10).
We cannot rule out that other diagnostic methods that are not limited to detection of neutralizing antibodies might have identified positive samples in our collection. Future analyses are required to determine MERS-CoV seroprevalence in larger patient collectives and in animal species, such as dromedary camels, that could transmit the virus to humans (4,11).
The lack of positives among children whose blood was taken in prior to May of 2011 is consistent with both the demographics of infection that we’ve seen (primarily affecting older adults), and with recent studies (see Lancet Article) that estimate of the emergence of MERS-CoV around as being around July, 2011 (95% HPD July, 2007, to June, 2012).
The authors also point out that the blood samples drawn from hospitalized children may have been collected early in their illness, before a virus antibody response had been generated.
The lack of positives among adult males, collected in December of 2012 is a bit more telling, as these samples were obtained 7 months after the first known outbreak in Jordan. However, at the time these blood samples were collected, only 7 laboratory confirmed cases of MERS had been detected in the Kingdom of Saudi Arabia.
While not conclusive, this study suggests that the MERS-CoV wasn’t circulating widely in the Eastern Province of Saudi Arabia prior to December of last year. Which supports the idea that this virus is probably a recent arrival to the human population, and not something that’s been infecting people, but going undiagnosed for years.
