Seroprevalence of
Hepatitis A virus infection in non-human primates in Assam, India
B.G. Nath 1, A.
Chakraborty 2, D.K. Sarma 3, T. Rahman 4& P.K. Boro 5
1 ICAR-Research Complex for NEH
Region, Sikkim Centre, Tadong, Sikkim 737102, India
2 Director of Research
(Veterinary), 3 Department of Microbiology, 4 Department
of Pathology, College of Veterinary Science, Assam Agricultural University,
Khanapara, Guwahati, Assam 781022, India
5 State Veterinary Dispensary, Bokakhat, Assam, India
3 Present address:
Director, National Research Centre (NRC) on Pig, ICAR, Rani, Guwahati, Assam
781131, India
1 drbichitra.nath@gmail.com
(corresponding author), 2 drapurba2@gmail.com,
3 dksarma1956@sify.com, 4 dr.taibur.rahman@gmail.com,5 boropk@rediffmail.com
doi: http://dx.doi.org/10.11609/JoTT.o3121.4722-4
Editor: Ulrike Streicher, Wildlife
Veterinarian, Danang, Vietnam. Date of publication: 26 August 2013 (online & print)
Manuscript details: Ms #
o3121 | Received 12 March 2012 | Final received 09 August 2013 | Finally
accepted 10 August 2013
Citation: Nath, B.G., A. Chakraborty,
D.K. Sarma, T. Rahman & P.K. Boro (2013). Seroprevalence
of Hepatitis A virus infection in non-human primates in Assam, India. Journal
of Threatened Taxa 5(12): 4722–4724; http://dx.doi.org/10.11609/JoTT.o3121.4722-4
Copyright: © Nath et al. 2013. Creative Commons Attribution 3.0 Unported License. JoTT
allows unrestricted use of this article in any medium, reproduction and
distribution by providing adequate credit to the authors and the source of
publication.
Funding: There is no funding agency.
This is a part of first author’s MVSc thesis.
Competing Interest: Authors
declare no competing interest.
Acknowledgements: The
authors are grateful to the authority of Assam State Zoo and Department of
Forest and Environment, Government of Assam for the materials and to the Head,
Department of Pathology, College of Veterinary Science, Assam Agricultural
University, Khanapara for providing the facilities.
For image, table -- click here
Hepatitis viruses have long
been assumed to be highly host-specific. However, among primates they seem to frequently cross between species.
For example infections of nonhuman primates occur due to inoculation with or
exposure to human viruses (Robertson 2001). Hepatitis A virus (HAV) is known to be
capable of infecting various species of primates, but new molecular biology
techniques have necessitated a re-evaluation of the ecology of this agent and
the role of non-human primates as natural hosts. Hepatitis A virus infection was reported
in wild-caught Chacma baboons (Smith et al. 1980), wild-caught Panamanian owl
monkeys (Lemon et al. 1982) and wild Cynomolgus macaques (Burke & Heisey
1984; Slighter et al. 1988). Enterically transmitted hepatitis viruses (hepatitis A virus and
hepatitis E virus) can induce hepatitis in a number of old world and new world
monkey species. The host range of
primates susceptible to hepatitis viruses transmitted by the parenteral route
is restricted to a few species of old world monkeys and apes (Vitral et al.
1998). The present study investigated
the seroprevalence of hepatitis A virus infection in non-human primates in
Assam.
Materials and Methods: From December 2007 to
November 2009, 37 serum samples of non-human primates were collected from Assam
State Zoo and Department of Forest and Environment, Government of Assam. A comprehensive data collection form
focused on possible risk factors including age, sex and living status
(household or free roaming) was prepared when sampling was carried out. Out of 37 sampled non-human
primates, 23 (62.16%) were males and 14 (37.83%) were females. Ten non-human primates were captive and
27 were free living. An additional
four serum samples were collected from animal keepers of Assam State Zoo
working with non-human primates.
Competitive ELISA was performed
using hepatitis A virus ELISA kit (Wanti Hep. AV) to detect
hepatitis A virus antibodies. Serum samples from the non-human primates
and humans were added in the appropriate wells of the ELISA plate precoated
with hepatitis A virus antigen. Monoclonal antibody linked with horse radish peroxidase conjugate was added simultaneously
after adding the serum samples. Serum and monoclonal antibody enzyme conjugate were allowed to react for
60 minutes at 370C. ELISA plate was washed five times with washed buffer supplied along with
the kit and after diluting 10 times with distilled water as recommended in the
kit. Substrate and chromogen
solution A consisting of urea peroxide solution and tetramethyl benzidine (TMB)
solution in citric acid was added to each of the wells of the ELISA plate and
allowed to react for 15 minutes at 370C. The reaction was stopped with 2M H2SO4and the reading of the plate was taken in ELISA reader (Multiscan Ex) using 450
nm filter. Blank, negative control and positive control were kept in the ELISA
plate as recommended in the kit.
The optical density (OD)
value for the positive serum control and negative serum control for detectable
antibodies were 0.101 and 1.349 respectively. The prevalence was estimated from
the ratio of positive results to the total number of animals examined. Assessment of association between
seroprevalence of anti-hepatitis A virus
antibodies in non-human primates and selected risk factors were made by
chi-square test by using SPSS 16 software.
Results: In the present investigation,
10 of 37 (27.02%) non-human primates and 3 of 4 (75%) human were found positive
for hepatitis A (VAH) infection as indicated by the serum titre (Image 1). The OD value recorded for positive
non-human primates samples were 0.130, 0.401, 0.498, 0.151, 0.334, 0.169, 0.156
0.434, 0.375, 0.168 and for zoo animal keepers were 0.163, 0.122, 0.127. From 10 non-human primates serum samples
with detectable antibodies, six (60%) were males and four (40%) were females
(Table 1). Statistical analysis
using chi-square test showed no correlation between hepatitis A virus infection
and gender (P=0.86). To investigate
the role of living condition in occurrence of infection, positively reacted
serum samples were compared between captive and free living non-human
primates. Infection rate had
significant difference between free living non-human
primates and captive non-human primates (P<0.05) (Table 1).
Discussion: Previously it was widely
accepted that the natural infection with HAV is limited to humans, although
several nonhuman primate species, including Chimpanzee, tamarins and owl
monkeys were susceptible to experimental infection. Serological evidence of infection had
been found in various species on non-human primates, including Rhesus and Crab-eating
Macaque, African Green Monkeys, baboons and owl monkeys (Dienstag et al.
1976). In the present study viral
hepatitis A infection rate in non-human primates was almost similar with the
infection rate recorded by Slighter et al. (1988) and Smith et al. (1980).
Comparison of infection rate
between two sexes showed no significant differences between males and females,
i.e., sex was excluded from possible risk factors of hepatitis A virus infection. A positive association was seen between
hepatitis A virus seropositivity and free livingnon-human primates. No infection in
captive non-human primate may be due to the lower chance of exposure, i.e.,
free living is a possible risk factor for hepatitis A virus infection. Presence of infected non-human primates
without clinical signs (even with high titers) indicates the importance of
these animals as possible carriers of the virus. The present study could not give any
statistical sense for the prevalence of hepatitis A infection in human as less
number of samples was examined. The
present study indicated the need for screening of a large number of non-human
primates and human samples particularly from zoo animal keepers to understand
the role of non-human primates in spreading hepatitis A virus infection.
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