Background

Camel filariasis induced variable clinical syndromes characterized by fever, lethargy, localized dermal lesions, loss of condition, and testicular and scrotal swelling. The objective of the present work focused on clarifying the diagnostic importance of clinical findings, serum testosterone, and semen analysis as well as blood smear and testicular histopathology as a differential tool between only balanoposthitis without filariasis male camels group (OnlyBp^gr) and balanoposthitis-filariasis infected male camels group (BpFl^gr). The study also monitored the associations between the severity of ticks’ infestations in investigated male camels and the occurrence of balanoposthitis only or balanoposthitis with filariasis.

Results and conclusions

The study reported significant correlation between serum testosterone, serum cortisol, and sperm vitality and abnormalities percentages. The study included male camels (n = 250) classified into three groups: healthy control group (Cont^gr; n = 30), OnlyBp^gr (n = 210), and BpFl^gr (n = 10). These male camels were clinically and laboratory examined, and skin scraping tests and testicular histopathology were conducted. The study confirmed the association of the changes in clinical findings, whole blood picture, serum testosterone, serum cortisol, and semen analysis, with OnlyBp^gr and BpFl^gr. These changes were more prominent in BpFl^gr than in OnlyBp^gr. Skin scraping test results revealed a higher severity of live ticks’ infestation in BpFl^gr than in OnlyBp^gr because, unlike OnlyBp^gr, all camels in BpFl^gr (n = 10) were suffering from live ticks’ infestation. It also concluded the higher efficacy of histopathology of testicular tissues in male camels as a diagnostic tool for adult filaria in balanoposthitis-affected male camels than blood smear because all cases of camel filariasis in the current work were negative for microfilaria on microscopic examination of diurnal blood smear as well as testicular histopathology revealed detection of adult filaria in all camel filariasis associated with balanoposthitis. Strong correlation relationships were demonstrated between serum testosterone, serum cortisol, and semen analysis results. Positive correlations were reported between serum testosterone levels and sperm vitality percentages. However, negative correlations were stated between serum testosterone and each of serum cortisol and sperm abnormalities either in Cont^gr, OnlyBp^gr, or BpFl^gr.

Many domestic and wild animals are susceptible to malignant catarrhal fever (MCF), which is a lymphoproliferative, multisystemic, and fatal disease. The present study was conducted on 47 cattle. The clinical examination findings revealed a persistent high fever, enlargement of superficial lymph nodes, corneal opacity, respiratory symptoms, oral lesions, and ulcerative skin lesions. Buffy coat samples were collected for laboratory analysis. Semi-nested polymerase chain reaction (PCR) assay has been used. Ovine herpesvirus-2 (OvHV-2) Deoxyribonucleic acid (DNA) was detected in the buffy coat of 21 cattle. DNA sequencing and phylogenetic analysis of OvHV-2 were performed in our study. The phylogenetic analysis of the PCR product of the Egyptian strain of OvHV-2 (Assiut) showed close similarity with OvHV-2 strains of different governorates (Beni-suef, Giza and Fayoum) of Egypt, India, Turkey, Iraq, Italy, Brazil and United Kingdom. There was no significant variation (P<0.05) between the percentages of MCF infection and the sex, age, and breed (native and mixed breed) of molecularly tested cattle. According to the climatologic conditions of Assiut governorate, there is no discernible difference (P<0.05) between the MCF infection rate and the cold and hot months. To date, this is the first report of OvHV-2 in Assiut Governorate, so it is advisable to separate susceptible cattle from sheep, especially during lambing, and to euthanize any animals that are clinically infected with MCF.

Twenty-four adult molly fish (Poecilia sphenops, Valenciennes 1846) were collected to study
the morphology and distribution of ganglia using histological, immunohistochemical, and electron
microscopy and focusing on their relation to the immune cells. The ganglia were classified spatially
into cranial and spinal, and functionally into sensory and autonomic. Spinal ganglia (dorsal root
ganglia, DRG) contained large close ganglionic cells, enclosed by satellite cells, as well as bundles of
both myelinated and non-myelinated nerve fibers. There are glial cells, immune cells and telocytes
close to the ganglion. In addition, oligodendrocytes were closely related to myelinated axons. Glial
fibrillary acidic protein (GFAP) expression was confined to the glia cells and the nerve fibers in
the cervical ganglia next to the gills, and surprisingly, in the large ganglionic cells of the DRG. The
vestibular ganglia were large, connected to the hind brain, and contained numerous neurons packed
in columns. The cervical ganglia were large and observed around the pseudobranch, head kidney,
and thymus. Their neurons are randomly distributed, and nerve fibers are peripherally situated.
CD3-positive T-lymphocytes, dendritic cells, and CD68-positive macrophages were in close contact
with the ganglia. Furthermore, the ganglia around the head kidney showed positive Iba1-expressing
cells. Most ganglion cells and nerve fibers in the DRG, autonomic, and vestibular ganglia showed
moderate to strong S-100 immunoreactivity. The enteric glia, CD68-expressing macrophages, and
acetylcholine (Ach)-expressing neurons were observed along the muscular layer of the intestinal wall.
In conclusion, different ganglia of molly fish displayed direct communication with immune cells
which support and maintain healthy ganglionic cells.

This study identified the cellular compositions of the gills in molly fish and their role
in immunity using light-, electron- microscopy, and immunohistochemistry. The molly fish gills
consisted of four holobranchs spaced between five branchial slits. Each hemibranch carried many
fine primary and secondary gill lamellae. The gill arch was a curved cartilaginous structure, from
which radiated the bony supports of the primary lamellae. The gill arch contained the afferent and
efferent brachial arteries. The gill arch was covered by epidermal tissue rich with mucous cells. The
primary lamella had a central cartilaginous support and efferent and afferent arterioles and was
covered with pavement cells (PVC), salt-secreting chloride cells, and pale-staining mucous cells.
These chloride cells contained abundant mitochondria and tubulovesicular system and are involved
in ionic transport with a potential role in detoxification. The surface of the secondary lamellae (site of
gaseous exchange) consisted of overlapping or interdigitating PVC supported and separated by pillar
cells. Other cells were found within the gill epithelium and interstitial connective tissues, including
lymphocytes, macrophages, monocytes, telocytes, stem cells, astrocytes, and neuroepithelial cells.
The immunohistochemical analysis revealed that APG-5, iNOS-2, IL-1, NF-B, and TGF-B showed
positive immunoreactivity in macrophages. The epithelium of the primary gill lamellae contained
positive-GFAP astrocytes and S100 protein—chloride cells. The stem cells expressed SOX9, myostatin,
and Nrf2. Neuroendocrine cells expressed S100 protein. In conclusion, the current work suggests
that the gills of molly fish are multifunctional organs and are involved in immune reactions.

The liver of fish is considered an ideal model for studying the collaboration between environmental agents and the
health state of the fish, where it gives good indications about aquatic ecosystem status. Therefore, this study presented
immune roles for the liver in molly fish (Poecilia sphenops), using immunohistochemistry and transmission
electron microscopy (TEM). The hepatocytes’ sinusoidal structures of molly fish livers had taken two different forms;
cord-like and tubular, while the biliary tract system showed two different types: isolated and biliary venous tract. The
TEM showed that the hepatocytes possessed well-developed cytoplasmic organelles and numerous glycogen and
lipid droplets of different sizes. Kupffer cells, Ito cells, aggregation of intrahepatic macrophages and melanomacrophages
were also recognized. Melanomacrophages contained numerous phagosomes, many lysosomes, cytoplasmic
vacuoles, and melanin pigments. Hepatocytes and Kupffer cells expressed immunoreactivity to APG5, indicating
that these cells were involved in the process of autophagy. Telocytes (TCs) were also recognized in the liver of molly
fish, and they shared the same morphological characteristics as those in mammals. However, TCs expressed strong
immunoreactivity to APG5, TGF-β, and Nrf2, suggesting their possible role in cellular differentiation and regeneration,
in addition to phagocytosis and autophagy. Both IL-1β and NF-KB showed immunoreactivity in the hepatocytes and
in inflammatory cells (including intrahepatic macrophages and melanomacrophage center). Nrf2 and SOX9 showed
immunoreactivity in hepatocytes, stem cells, and macrophages. The present study showed the spatial distribution of
hepatic vascular-biliary tracts in molly fish. The liver of molly fish has unique functions in phagocytosis, autophagy,
and cell regeneration. The expression of APG5 in hepatocytes, Kupffer cells, melanomacrophages, and telocytes supports
the role of the liver in lymphocyte development and proliferation. The expression of TGF-β and NF-κB in hepatocytes,
Kupffer cells, telocytes, and macrophages suggests the role of the liver in regulation of cell proliferation and
immune response suppression. The expression of IL-1β and Sox9 in macrophages and melanomacrophages suggests
the role of the liver in regulation of both innate and adaptive immunity, cell proliferation and apoptosis, in addition to
stem cell maintenance.

The pseudobranch is a gill-like structure that exhibits great variations in structure and function
among fish species, and therefore, it has remained a topic of investigation for a long time. This
study was conducted on adult Molly fish (Poecilia sphenops) to investigate the potential functions of
their pseudobranch using histological, histochemical, immunohistochemical analysis, and scanning
electron microscopy. The pseudobranch of Molly fish was of embedded type. It comprised many rows
of parallel lamellae that were fused completely throughout their length by a thin connective tissue.
These lamellae consisted of a central blood capillary, surrounded by large secretory pseudobranch
cells (PSCs). Immunohistochemical analysis revealed the expression of PSCs for CD3, CD45,
iNOS-2, and NF-κB, confirming their role in immunity. Furthermore, T-lymphocytes-positive CD3,
leucocytes-positive CD45, and dendritic cells-positive CD-8 and macrophage- positive APG-5 could
be distinguished. Moreover, myogenin and TGF-β-positive PSCs were identified, in addition to nests
of stem cells- positive SOX-9 were detected. Melanocytes, telocytes, and GFAP-positive astrocytes
were also demonstrated. Scanning electron microscopy revealed that the PSCs were covered by
microridges, which may increase the surface area for ionic exchange. In conclusion, pseudobranch
is a highly specialized structure that may be involved in immune response, ion transport, acid–base
balance, as well as cell proliferation and regeneration.