Zika virus can persist in the male reproductive system and negatively impact fertility. A recent study in mice found that Zika virus infected the testes, sperm, and epididymis up to 21 days after infection. This led to testicular damage, lower sperm counts, decreased testosterone production, and impaired fertility as female mice mated with infected males had lower rates of pregnancy. The study suggests Zika virus prefers cells involved in sperm formation and disrupts the function of Sertoli cells, leading to germ cell death and destruction of seminiferous tubules, indicating Zika infection has the potential to reduce male fertility in humans.

1. LOVELY PROFESSIONAL UNIVERSITY,PHAGWARA
Zika virus
Impact on male fertility
Chetana rai
11/3/2017
( RZ1652A03 )
Abstract : Zika virus is a arbovirus which belongs to genus flavivirus and family
Flaviviridae and transmitted to humans via the bite of infected mosquitoes.It is
known to cause microcephaly in infants and Guillain-Barré syndrome and
meningoencephalitis in adults.A recent study shows it also had a great impact
on male fertility which is nowadays a concern.

2. 1
S.No INDEX Page No.
1. Introduction 2
2. Classification 2
3. Genome 2
4. History 3
5. Epidemology 4-5
6. Structure 6-7
7. Transmission 8
8. Clinical manifestation 9
9. Methods 9
10. Results 10
11. How Zika virus effect male fertility 11
12. Conclusion of study 11
13. References 12

3. 2
KEYWORDS: Flavivirus, Microcephaly, Semen, Fertility
INTRODUCTION
Zika virus is a arbovirus belong to genus Flavivirus and the family Flaviviridae.The
flavivirus comprised of 52 viral species which include dengue, Saint Louis encephalitis,West
Nile viruses and Yellow fever.The flavivirus are a family of positive sense,enveloped,non-
segmented,single stranded RNA viruses which is approximately 11kb in length.
Zika virus is a causative agent of Zika virus Diseases i.e microcephaly, Guillain-Barré
syndrome and meningoencephalitis. The diseases is primarily spread by different species of
Aedes mosquitoes which is also vector for dengue fever and chikungunya virus. Zika virus
named so becuase it was found in the Zika forest of Uganda which mean “overgrown” in the
Luganda language.
BALTIMORE CLASSIFICATION OF ZIKA VIRUS
Group IV: (+) Positive sense, single-stranded RNA virus
Order = Unassigned
Family = Flaviviridae
Genus = Flavivirus
Species = Zika virus
GENOME OF ZIKA VIRUS
The genomic RNA of Zika virus is 10794 bp long which has a open reading frame which is
flanked by 5′ and 3′ non-coding regions. The genome is translated into a single poly-protein
that is later cleaved by viral as well as host cell enzymes, resulting in 3 structural proteins
that form the virion (made up of capsid, envelope and membrane) and 7 non-structural
protein which are NS1, NS2a, NS2b, NS3, NS4a, NS4b and NS5.

4. 3
HISTORY
Zika virus was first identified in Uganda in 1947.It was first isolated from the serum of
sentinel Rhesus monkey while study the cause of transmission of yellow fever. Then it was
isolated from the same forest from a pool of Aedes africanus mosquitoes in 1948. It was later
identified in human in 1952. Zika virus is primarily transmitted to human through bite of an
infected mosquito from Aedes genus mainly Aedes aegypti.

5. 4
EPIDEMOLOGY
1947 Routine surveillance for Yellow fever in the Zika forest of
Uganda, ZIKV was isolated in sample taken from the capitive
sentinel rhesus monkey.
1954 The virus is isolated from a girl in Eastern Nigeria.
1964 A researcher in Uganda who fell ill while working with Zika
strains isolated from mosquitoes provides the first proof, by
virus isolation and re-isolation, that Zika virus causes human
disease. Since then, Zika virus is known to be causing
sporadic human infections in Africa and Asia.
1969-1983 Geographical distribution of Zika expands to equatorial Asia
(India, Malaysia, Indonesia, and Pakistan), where the virus is
detected in mosquito.
2007 First large outbreak in humans on the pacific island of Yap. An
estimated 73% of Yap residents over 3years of age were
infected with Zika virus. The first major outbreak, with 185
confirmed cases, was reported
2013-2014 Outbreaks in 4 other groups of Pacific island: French Polynesia,
Easter Island, the Cook Islands and New Caledonia
Oct 2015 There are 3174 cases and 38 deaths from microcephaly in
Brazil and there has been reported total death of 152 in the
world. Outbreak in French Polynesia is intensively investigated
Nov 2015-
Jan 2016
The results are reported to WHO. These reports indicate a
possible association between Zika virus infection and cogenital
malformations and severe neurological and autoimmune
complications.
Feb,2015 Brazil detect cases of fever and rashe which are expected
because of Zika virus.
May 2015 Cases of fever and rashes that were confirmed to be Zika virus.
Feb 2016 The public health authorities of another 30 countries and
territories in the Americas also reported the indigenous
circulation of ZIKV.
This is the largest ZIKV outbreak which is ever recorded.

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7. 6
STRUCTURE
In the older days,to resolve the structure of zika virus was a big deal.The first virus tructure
was solved by X-ray crystallography but Zika virus structure was difficult to explored by X-
ray crystallography so it was done by cryo-electron microscopy(cryo-EM) which is
comparatively easier and faster than X-ray crystallography.To know structures by
cryoelectron microscopy, virus sample after purified are rapidly frozen and photographed
with an electron microscope at very low temperatures. It preserves its native structure, and
allows visualize the contrast induced by the virus particle.Then the photographs of number
of virus particles - each in a slightly different orientation - are taken and processing
computationally to create a 3D image.
Fig.. Structure of Zika virus
The cryo-EM structure of Zika virus shows that Its structure consist of a membrane
surrounding the capsid, which carries the viral RNA genome. . The structure had first two
carbohydrates sugar attached to an aspargine aminoacid in the envelop protein The membrane
composed of phospholipid cholestrol which is taken from host cell endoplasmic
reticulum.The membrane of virus particle consists of 180 copies of the viral proteins E and
M. Each protein is glycosylated and had a loop that is embedded into membrane via their
transmembrane region.
The E proteins are the major protein which involved in fusion and binding with receptor of
host cell. The M proteins are minor proteins that enclosed by the E protein layer.These minor
protein are important for proper assembly of E proteins. The E and M proteins are arranged to
form a icosahedral symmetry which made up of 60 repeating units, and each unit contains 3
individual E proteins i.e molecules A, B and C. The E proteins are arranged to form dimers,
which had 3 dimers arranged parallel to each other to form a raft like structure.There are 30
such rafts covering the viral surface. The ectodomain of E proteins contains 3 domains i.e
DI, DII and DIII in which DI acts as a link in between DII and DIII. The initial point of DII
contains a fusion loop, that can interacts with the endosomal membrane during fusion. The
DI-DII hinge regions of E domain is important for flipping out DII so that it can expose the
fusion loop during the fusion event. The DI-DIII hinge is rigid at neutral pH.

8. 7

9. 8
TRANSMISSION
Zika virus is primarily spread through bite of an infected female mosquito,commonly by
Aedes aegypti species.Zika virus RNA also been isolatedin urine,saliva,amniotic fluid and
placental tissue which highlight the possibility its other modes of transmission. It can
transmitted
 Through mosquito bites- It is the primary way to transmission of Zika
virus,which occur through bite os an infected female mosquito during blood feed.
 Rarely from mother to child- Pregnant woman are on high risk of Zika virus . It
pass from a mother to her fetus if she is infected during pregnancy which lead to
microcephaly in newborn.
 Through sexual contact.- Strains of ZIKV also found in semen of patient several
weeks after the acute phase of the Zika virus diseases.There are also some cases
of sexual transmission has reported.
 Through blood transfusion- ZIKV present in blood stream of infected person
which can transmitted through transfusion.

10. 9
CLINICAL MANIFESTATION
Most of the cases are subclinical or asymptomatic. In symptomatic cases, symptoms are last
for few days .The most common symptoms are maculopapular rash, prostration, headache,
back pain, low grade fever.
In severe condition of ZIKV diseases complications arises like Lymphadenopathy,
Haematospermia, Guillain-Barre syndrome (a condition in which your immune system
attacks part of nervous system), birth defects such as microcephaly,( a condition where a
baby’s head is much smaller than expected and can cause developmental delays).
Previously it was thought that the virus, which is passed on through mosquito bites, was only
dangerous for pregnant women, because it can lead to babies being born with shrunken heads
and brain damage, a condition known as microcephaly. In rare cases it can also lead to
Guillain-Barre syndrome which can cause paralysis and lead to death.
‘The recent research shows that virus might persist in semen longer than in blood and
can cause infertility to male.’
METHODS
Mostly researches are done to understand the consequences of Zika virus infection which
mainly focused on that how the virus affects pregnant women and how it can causes severe
birth defects in their developing fetuses.But a recent study which made on experimental
animal i.e mice suggests that Zika infection also may have alarming consequences for men
that is related to interference with their ability to have children i.e effect male fertility.
In a new mouse study, a team of investigators led by Kelle Moley and Michael Diamond has
shown that ZIKV persists in the testes, sperm and epididymis of mice 21 days after infection
and that persistence of the virus is associated with testicular damage, oligospermia and
severely impaired male fertility.
The team infected wild-type C57BL/6 mice with mouse-adapted African ZIKV (strain Dakar
41519) or the closely related Dengue virus (DENV) (strain D2S20).
To facilitate infection and dissemination of the viruses, mice were also administered a single
dose of a blocking monoclonal antibody that suppressed IFN α/β receptor 1 signalling.
 Within 7 days of infection, viral RNA and infectious particles were detected in all
tissues of the male reproductive tract of mice infected with ZIKV but not in those
infected with DENV.
 By day 14, the blood–testis barrier was breached and the virus was detected
throughout the testes in ZIKV-infected mice. Marked infiltration of CD45+ cells and
testicular cell death were also noted.

11. 10
 Persistence of the virus at day 21 was accompanied by progressive destruction of the
testes (noticeably reduced size and weight), reduced production of testosterone and
inhibin-β, and decreased sperm counts (both total and motile). Crucially, fecundity
was lower in female mice mated with ZIKV-infected male mice than in female mice
mated with uninfected controls.
Caption: Immunofluorescence staining showing that the testes of Zika-free mice
(left) are full of developing sperm (pink), while the testes of Zika-infected mice (right) contain
very few sperm.
RESULT OF STUDY
The consequences of infection in the male reproductive tract of mice was evaluated by a team
of scientists by using a mouse which have invitro adapted Zika virus strain(Dakar 41519).
They observed that Zika virus persist again, but it was not the closely related to dengue virus,
in the epididymid and testes of male mice, and this was associated with tissue injury that
caused diminished testosterone and oligospermia and can also inhibin B levels. ZIKV
preferably infected formation of sperms,spermatogonia, primary spermatocytes and damage
Sertoli cells in the testis,which resulting in cell death and destruction of the seminiferous
tubules.

12. 11
HOW ZIKA VIRUS AFFECT MALE FERTILITY
 ZIKV is found mainly in Sertoli cells (the cells which nourishing developing sperm
cells), mitotic cells,and midmeiotic cells in the testis. The viral load in epididymal
spermatozoa is already significant after 7 days of infection. This observation
indicates that ZIKV can infect spermatozoa directly and efficiently in the epididymal
lumen.
ZIKV preferably infect Sertoli cells,spermatogonia,and primary spermatocytes in the
testis which resulting in cell death and finally lead to destruction of the seminiferous
tubules.
 The testicular interstitial cells mostly consists of the steroidogenic Leydig cells and
leukocytes which are virus-free up to day 21 postinfection, but Sertoli cells seems to
be particularly susceptible to ZIKV infectionAlthough the Sertoli cells are fairly
robust, impairment of their function can quickly accelerate and magnify the extent of
spermatogenic damage, as each Sertoli cell sustains dozens of germ cells at different
stages of their development.
CONCLUSION
All previously researches are made to understand the consequences of Zika virus
infection on pregnant women and its causes severe birth defects in their developing
fetuses.
But Recent research has shown that the mosquito-borne Zika virus has the potential to
cause impact on male fertility.
This study on mice suggest that men might face low testosterone levels and low sperm
count after Zika infection which affect their fertility.
“The more we learn about the Zika virus, the more interesting
and alarming it becomes’’.

13. 12
REFERENCES
 http://dx.doi.org/10.1038/nature20556 (2016)
 http://www.nature.com/nrendo/journal/v13/n1/full/nrendo.2
016.191.html
 https://directorsblog.nih.gov/2016/11/08/could-zika-virus-
have-lasting-impact-on-male-fertility/
 https://www.niaid.nih.gov/diseases-conditions/zika-virus
 http://www.telegraph.co.uk/science/2016/10/31/zika-virus-
could-cause-infertility-in-men-new-study-suggests/
 http://www.nature.com/nature/journal/v540/n7633/full/natu
re20556.htm
 https://www.sciencedaily.com/releases/2017/01/17012309472
6.htm
 http://www.ncbi.nlm.nih.gov/pubmed/26914735