Most Read Articles
4 days ago
A recent study has assessed the long-term safety of nine systemic medications for psoriasis, revealing the lowest incidence of adverse events with ustekinumab and secukinumab.
Jairia Dela Cruz, 4 days ago
Following vegan and vegetarian diets, which offer plenty of what is good for health, has been reported to have a downside: an increased risk of depression and anxiety, especially for younger adults.
Pearl Toh, 2 days ago
Taking 600 mg aspirin daily significantly reduces the risk of colon cancer over 10 years in people with Lynch syndrome — which genetically predisposes them to colon cancer, the CAPP*2 study shows.
30 Jun 2020
Patients with psoriatic arthritis (PsA) often suffer from liver abnormalities, which are associated with higher body mass index (BMI), daily consumption of alcohol, more severe disease, and some therapies, according to a recent study.

SARS-CoV-2 can infect through conjunctiva

Natalia Reoutova
02 Jun 2020
The conjunctival epithelium and conducting airways appear to be potential portals of infection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), according to a study in ex vivo cultures of human bronchus, lung and conjunctiva.

“SARS-CoV-2 can be detected in patients’ tears, conjunctiva, and anal swabs; thus, it is important to study the potential for experimental infection of extrapulmonary tissues,” wrote the study authors. [J Med Virol 2020;92:589-594; Emerg Microbes Infect 2020;9:386-389]

The researchers at The University of Hong Kong isolated SARS-CoV-2 from a patient with confirmed coronavirus disease 2019 (COVID-19) in January 2020. They used fresh non-tumour conjunctiva (n=3), bronchus (n=5), and lung (n=4) tissues obtained from patients undergoing elective surgery to assess the tropism and replication competence of the virus in these tissues and compare it with that of the Middle East respiratory syndrome coronavirus (MERS-CoV), SARS-CoV and H1N1pdm. [Lancet Respir Med 2020, doi: 10.1016/S2213-2600(20)30193-4]

Human conjunctival explant cultures were more extensively infected by SARS-CoV-2 than by SARS-CoV, as shown by immunohistochemical (IHC) staining and higher infectious viral titres at 48 hours post-infection (hpi). “The demonstration of infection of conjunctiva suggests that the eye might be an additional route of infection, an observation that is crucially relevant for infection prevention and control,” wrote the researchers.

IHC staining also showed that SARS-CoV-2 extensively infected bronchial epithelium, with infection observed in ciliated cells, non-ciliated mucus secreting (goblet) cells, and club cells, but not basal cells. “The conjunctival epithelium and conducting airways appear to be potential portals of infection of SARS-CoV-2,” commented the researchers.

The researchers also infected human colorectal carcinoma cells with SARS-CoV-2 and demonstrated infection and productive replication of the virus, which hints at virus infection and replication in the gastrointestinal tract and might indicate the possibility of oral-faecal transmission as an additional route.

Similar bronchus tissue tropism was observed between MERS-CoV, SARS-CoV, and H1N1pdm, while viral antigen staining was more extensive with SARS-CoV-2. SARS-CoV-2 replicated more efficiently than SARS-CoV in ex vivo cultures of human bronchus, with peak viral titres at 96 hpi. “Both SARS-CoV and SARS-CoV-2 replicated similarly in the alveolar epithelium, but SARS-CoV-2 replicated extensively in bronchial epithelium, which might explain the robust transmission of this pandemic coronavirus,” the researchers proposed.

The viral titres of SARS-CoV-2 at 24 hpi and 48 hpi were significantly lower than that of H1N1pdm. “This observation is compatible with the longer incubation period of SARS-CoV-2 than that of H1N1pdm. Virus shedding before symptom onset probably contributes to the difficulty of controlling the spread of SARS-CoV-2 by public health interventions – much more so than with SARS-CoV,” commented the researchers. [Engl J Med 2020;382:1177-1179; Lancet Infect Dis 2020;20:411-412]

In lung tissues, similar viral antigen staining was observed with SARS-CoV-2, SARS-CoV and H1N1pdm – all of which were less extensive than that with MERS-CoV. In the lung parenchyma, there was positive antigen staining for SARS-CoV-2 in the spindled, morphologically epithelial type 1 pneumocytes, which are crucial in the process of gas exchange between the alveoli and the capillaries. “Damage to type 1 pneumocytes might account for the acute lung injury of severe cases of COVID-19,” hypothesized the researchers.  

“Our findings support the notion that SARS-CoV-2 can be transmitted between humans via droplets deposited in the airways or eyes, and via fomite transmission when infectious virus is introduced to the eyes via contaminated hands,” concluded the researchers.
Editor's Recommendations
Most Read Articles
4 days ago
A recent study has assessed the long-term safety of nine systemic medications for psoriasis, revealing the lowest incidence of adverse events with ustekinumab and secukinumab.
Jairia Dela Cruz, 4 days ago
Following vegan and vegetarian diets, which offer plenty of what is good for health, has been reported to have a downside: an increased risk of depression and anxiety, especially for younger adults.
Pearl Toh, 2 days ago
Taking 600 mg aspirin daily significantly reduces the risk of colon cancer over 10 years in people with Lynch syndrome — which genetically predisposes them to colon cancer, the CAPP*2 study shows.
30 Jun 2020
Patients with psoriatic arthritis (PsA) often suffer from liver abnormalities, which are associated with higher body mass index (BMI), daily consumption of alcohol, more severe disease, and some therapies, according to a recent study.