|Year : 2018 | Volume
| Issue : 1 | Page : 113-115
Molecular epidemiology of circulating human adenovirus types in acute conjunctivitis cases in Chandigarh, North India
Mini P Singh1, Jagat Ram2, Archit Kumar1, Tripti Rungta1, Amit Gupta2, Jasmine Khurana1, Radha Kanta Ratho1
1 Department of Virology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
|Date of Web Publication||2-May-2018|
Dr. Mini P Singh
Department of Virology, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
Human adenovirus (HAdV) is a major cause of viral conjunctivitis. The various serotypes implicated in the causation are 3, 4, 8, 19 and 37. The present study aimed to know the circulating types of HAdV causing acute conjunctivitis in North India. A total of 23 conjunctival swabs were collected from patients with clinically suspected acute viral conjunctivitis during 2014–2015. The HAdV was implicated in the etiology in 65.2% of cases. The sequencing of representative samples using hexon gene suggests the presence of serotype 8 and 4. The serotype eight sequences showed 99%–100% similarity with other Indian strains. The phylogenetic analysis showed that the current circulating serotypes, responsible for conjunctivitis, belonged to epidemic keratoconjunctivitis strains.
Keywords: Conjunctivitis, human adenovirus, molecular epidemiology
|How to cite this article:|
Singh MP, Ram J, Kumar A, Rungta T, Gupta A, Khurana J, Ratho RK. Molecular epidemiology of circulating human adenovirus types in acute conjunctivitis cases in Chandigarh, North India. Indian J Med Microbiol 2018;36:113-5
|How to cite this URL:|
Singh MP, Ram J, Kumar A, Rungta T, Gupta A, Khurana J, Ratho RK. Molecular epidemiology of circulating human adenovirus types in acute conjunctivitis cases in Chandigarh, North India. Indian J Med Microbiol [serial online] 2018 [cited 2019 Feb 23];36:113-5. Available from: http://www.ijmm.org/text.asp?2018/36/1/113/231663
| ~ Introduction|| |
Acute viral conjunctivitis is usually a self-limiting condition characterised by acute follicular conjunctival reaction and preauricular lymphadenopathy. The common etiological agents include adenovirus, herpes simplex virus, varicella-zoster virus, enterovirus 70, coxsackie A24 and human immunodeficiency virus., Human adenovirus (HAdV) is the most common agent involved in viral conjunctivitis accounting for 65%–90% of the cases. HAdVs belong to the genus Mastadenovirus, containing seven species HAdV-A to HAdV-G with 85 genotypes. HAdV Types 3, 4, 8, 37, 54, 56 and 64 are the ones implicated in keratoconjunctivitis., The latter usually occurs in epidemics and is highly contagious and patients present with red-eye, severe chemosis and mucus discharge. The main route of the transmission of the virus is through direct contact with infected secretions and also through fomites.
Worldwide, various outbreaks of keratoconjunctivitis associated with HAdV have been reported of which the Type 8 is mainly responsible. The studies from India have reported the presence of Type 2, 3, 4, 6, 7, 8 and 37.,,,, The molecular epidemiology of the circulating strains is important to understand the virus transmission worldwide. The aim of the present study was to identify the circulating types of HAdV in acute conjunctivitis cases in Chandigarh, North India.
| ~ Materials and Methods|| |
The conjunctival swabs were collected from 23 sporadic cases with clinically suspected adenoviral conjunctivitis visiting Advanced Eye Center, PGIMER, Chandigarh in 2014–15, after obtaining informed written consent. The study was approved by Institute ethics committee as per national guidelines. The disease was clinically graded as mild, moderate and severe based on the presence of chemosis and mucus discharge by JR and AG.
The samples obtained were transported to the virology laboratory in viral transport medium in the cold chain. The DNA was extracted using the commercially available kit as per the manufacturer's instructions (Qiagen, Germany) and subjected to nested polymerase chain reaction (PCR) targeting hexon gene of HAdV. The amplification was carried out in 25 μl reaction containing 10 mM Tris, 1.5 mM MgCl2, 0.5 μM of each primer  and 1U Taq polymerase (Genei, Bangalore). The cycling conditions were: Initial denaturation at 94°C for 5 min, followed by 35 cycles of 94°C for 1 min, 55°C for 1 min, 72°C for 2 min and final extension at 72°C for 7 min. The amplified products from the 1st round were used for 2nd round amplification by using the same amplification reactions as above. The outer primer sequences were forward = 5'GCCACCTTCTTCCCCATGGC3' and reverse = 5'GTAGCGTTGCCGGCCGAGAA3' and the forward and reverse nested primer sequences were 5' TTCCCCATGGCCCACAACAC 3' and 5' GCCTCGATGACGCCGCGCTG 3', respectively.
The representative samples were processed for type identification. The products of 916 bp were separated by agarose gel electrophoresis, followed by gel elution using Qiagen Gel Extraction Kit (Qiagen, Germany). These products were then sequenced using Sanger method followed by BLAST confirmation. The sequences were then aligned by using ClustalX2.0.11 software (University College Dublin, Dublin, Ireland), and phylogenetic tree was constructed by using Neighbor-Joining algorithm with bootstrap 1000 replicate by using MEGA6.0 software (Center for Evolutionary Medicine and Informatics, Tempe, USA).
| ~ Results and Discussion|| |
The mean age of the patients was found to be 43.9 ± 17.7 years with male:female ratio of 3.6:1. The conjunctivitis was unilateral in 12 patients (52.2%) and bilateral in 11 patients (47.8%). The disease was graded as mild, moderate and severe-based on the presence of chemosis in 9 (39.1%), 13 (56.5%) and 1 (4.4%) patient, respectively. A total of 16 (69.6%) and 7 (30.4%) patients reported mild and moderate mucus discharge, respectively.
Out of 23 samples collected, 15 (65.2%) were found to be positive for HAdV by nested PCR. A total of 7 representative samples were subjected to sequencing, out of which 6 were found to be Type 8 and 1 of Type 4. The sequences were submitted to Genbank vide accession numbers KX431315–18, KX4313120–22. The BLAST analysis showed a sequence identity of 99%–100% for Type 8 with sequences from Hyderabad, New York, Tunisia. For Type 4, 100% identity was observed with Tunisian and Chinese sequences. In the phylogenetic analysis, Type 8 and Type 4 clustered with similar types under Group D and E, respectively [Figure 1].
|Figure 1: Phylogenetic analysis of Postgraduate Institute of Medical Education and Research isolates along with various other types of human adenovirus|
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In the present study, positivity of 65% was observed for HAdV among patients with acute conjunctivitis. The previous studies from India have shown the positivity of 13.8%–66.6% for HAdV among the patients with keratoconjunctivitis.,,, Among the various species of HAdV (A-G), B, D and E are more commonly involved in conjunctivitis. In the present study, the authors identified the presence of HAdV Types 8 and 4 belonging to the Group D and E, respectively, by using primers targeting the hexon region. Worldwide, the Genotype 8 is more prevalent (involved in up to 44%–100% of epidemic keratoconjunctivitis outbreaks), whereas Type 4 is implicated in 7%–11% of outbreaks. In the present study, Type 8 was involved in 6/7 (85.7%) and Type 4 in 1/7 (14.3%) of represented samples. The studies from India have previously reported the presence of Type 8 from Pune and Puducherry in 78.6% and 100% of cases, respectively, and Type 4 from Chennai and Pune (7.2%).,
In the present study, the phylogenetics relatedness was not possible with sequences from Pune as latter was sequenced using penton and fibre gene. However, sequence identity of 99%–100% was observed for Type 8 to that of other Indian strains from Hyderabad (KR303745, KR303748–50) and Puducherry (KR150657–667). The present study suggests the predominance of Type 8 strains and their similar circulating patterns in India.
It is important to carry out the sequencing and phylogenetics analysis to identify any variation in circulating types. Only a few countries, such as the US and Japan, are doing appropriate surveillance of HAdV. Limited literature is available from North India concerning the molecular identification and genotyping of HAdV. The present study adds up to the knowledge of existing circulating strains of HAdV from North India. Further molecular studies will help to the identification and origin of outbreaks and development of control programmes.
The study was funded by Department of Science and Technology (U. T.), Chandigarh vide the sanction number SandT/SANC/09/2013/1091–1096 Dated 9/9/13.
As mentioned in acknowledgment.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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