Transmission of Sarcocystis leporum from a cottontail rabbit to domestic cats.

Muscle tissue containing grossly visible cysts of Sarcocystis leporum from a cottontail rabbit (Sylvilagus floridanus) was fed to laboratory cats. Sporocysts averaging 13.2 x 9.7 micron were detected in the feces 14 days post-infection and were found until 69 days post-infection.     

Transmission of feline immunodeficiency virus in domestic cats via artificial insemination.

The objective of this study was to determine whether semen from male domestic cats infected with feline immunodeficiency virus (FIV) can transmit virus to females. Twelve inseminations were performed by an intrauterine laparoscopic technique with fresh or cryopreserved electroejaculates from asymptomatic males chronically infected with the NCSU1 strain of FIV. Of six inseminations performed with fresh semen, three resulted in infection of queens, as indicated by seroconversion, expression of FIV gag provirus in peripheral blood leukocytes, and reduced peripheral CD4+/CD8+ T-lymphocyte ratios. None of the six inseminates with thawed cryopreserved semen resulted in infection. Two infected queens and one uninfected queen became pregnant. Virus was not evident in the seven offspring. We conclude that FIV can be transmitted horizontally by artificial insemination with fresh semen.     

Infection and Rapid Transmission of SARS-CoV-2 in Ferrets

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Transmission from vaccinated individuals in a large SARS-CoV-2 Delta variant outbreak

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Transmission of Toxoplasma gondii in an urban population of domestic cats (Felis catus)

Toxoplasma gondii is a protozoan parasite that infects humans and animal species worldwide. The relative importance of each potential transmission route in the complex life cycle of this coccidia is largely unknown, due to the lack of studies taking into account all routes simultaneously. In this study, we analyzed the transmission of T. gondii in an urban population of stray cats captured between 1993 and 2004. Analyzing prevalence, our aim was to determine which factors influence transmission in this population. Specific anti-T. gondii IgG antibodies were detected using the modified agglutination test. Firstly, we analyzed the kinetics of antibody titers in cats captured several times, using mixed linear models and correspondence analysis. We showed that antibody titers did not vary significantly with time and that titer 40 was the best threshold to separate individuals into two serological groups. Overall, prevalence was only 18.6%, thus transmission of T. gondii is infrequent in this population. As expected, a highly significant association was detected between age and presence of IgG antibodies. Prevalence was lowest in kittens aged 3-4 months, suggesting that newborn kittens may carry maternal antibodies and that vertical transmission is rare. After taking into account the effect of age, logistic regression showed that antibody carriage was related to factors that possibly related to the survival of oocysts: localization in the study site, origin of the cats, maximal temperatures and rain. Our results suggest that in this population, vertical transmission is rare, low predation limits prevalence, and oocyst survival is a determining factor in the risk of infection. We discuss the more general importance of conditions determining oocyst survival in the life cycle of T. gondii.     

The daytime behaviour of domestic cats in a free-roaming population

The cats (Felis catus) of this study were found to fluctuate daily between solitary and group living. These temporal changes in behaviour were interpreted as reflecting adjustments made by the cats for maximum use of different food sources available at these times. The dependence on both a solitary and communal life style for food procurement prevented any intricacy of either pattern from evolving. The structure of each behavioural pattern is discussed.     

Natural Transmission and Experimental Models of SARS-CoV-2 Infection in Animals

Since the World Health Organization declared COVID-19 a pandemic in March 2020, millions of people have contracted SARS-CoV-2 and died from the infection. Several domestic and wild species have contracted the disease as well. From the beginning, scientists have been working to develop vaccines and establish therapies that can prevent disease development and improve the clinical outcome in infected people. To understand various aspects of viral pathogenesis and infection dynamics and to support preclinical evaluation of vaccines and therapeutics, a diverse number of animal species have been evaluated for use as models of the disease and infection in humans. Here, we discuss natural SARS-CoV-2 infection of domestic and captive wild animals, as well as the susceptibility of several species to experimental infection with this virus.

In December 2019, several health facilities in China reported cases of patients with pneumonia of unknown cause. Epidemiologic studies linked the majority of the affected patients with a seafood and wet-animal wholesale market in Wuhan, China.⁹⁴ The patients presented with fever, cough, and chest discomfort; 2 of the first 3 patients recovered, whereas the remaining one died. RNA extracted from the bronchoalveolar-lavage fluid of one patient was sequenced, and a viral sequence that had 85% identity with a SARS-related coronavirus isolated from a bat was identified. The same specimen was used for viral isolation, and the isolate was originally named 2019-nCoV. Genomic and phylogenetic analysis revealed similarities of the newly identified virus with bat coronaviruses and differences from severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). The newly isolated virus belongs to a clade within the subgenus Sarbecovirus and differs from SARS-CoV and other SARS-related virus strains. Because the sequence identity in the 1ab open reading frame (conserved replicase domain) was less than 90% between 2019-nCoV and other betacoronaviruses, the virus was classified as a novel betacoronavirus, subgenus Sarbecovirus, family Coronaviridae.⁸⁴ The virus has since been officially renamed by the International Committee on Taxonomy of Viruses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with the disease caused by SARS-CoV-2 called COVID-19.¹⁷ As of 13 September 2021, more than 330 million cases of COVID-19 have occurred, and the disease has claimed more than 4.6 million human lives worldwide.⁸⁶SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) as the cellular receptor for virus binding.³⁴ The interaction between the virus spike protein and the host-cell ACE2 protein is mediated by the receptor binding domain (RBD) present in the spike protein. The RBD of the spike protein is highly variable among coronaviruses, and is under constant selection pressure. The affinity of the RBD of the spike protein with the cellular receptor determines the host range of coronaviruses.²⁵ Unlike the spike protein of SARS-CoV, the spike protein of SARS-CoV-2 is preactivated by the proprotein convertase furin prior to cell entry; the cell-surface protease transmembrane serine protease 2 and lysosomal cathepsin protease also participate in cell entry. The SARS-CoV-2 RBD binds to human ACE2 (hACE2) with higher affinity than does SARS-CoV. In contrast, the spike protein as a whole has lower affinity for hACE2, suggesting that the SARS-CoV-2 RBD provides a way to evade the immune system while still allowing efficient cell entry.^66,67The current coronavirus outbreak represents the third transmission of coronaviruses from animals to humans in the last 2 decades. In 2002, an outbreak of SARS-CoV in China caused 916 deaths (case fatality rate of 11%).^12,21 In 2012, another related coronavirus, Middle East Respiratory Syndrome coronavirus (MERS-CoV), emerged in Middle Eastern countries, with a mortality rate of 34%.^86,88 Several studies on the evolution of these viruses^18,25,26 and more recently on SARS-CoV-2¹ point to bats as the origin of infection for all 3 viruses.As for SARS-CoV and MERS-CoV, SARS-CoV-2 likely moved from bat reservoirs to a yet-unknown intermediate host and then to humans.^1,92 Masked civet cats and dromedary camels have been identified as the intermediate host for SARS-CoV and MERS-CoV, respectively.^73,89 Notably, several animal species seem to be naturally susceptible to SARS-CoV-2 infection, mainly due to the highly conserved nature of the ACE2 protein among diverse animal species, especially mammals. Pangolins,⁴⁴ dogs⁵⁸ and snakes⁴⁶ were under investigation as potential intermediate hosts for SARS-CoV-2. However, the animal species that enabled transmission to humans has yet to be determined. Natural infections have been reported in dogs, domestic cats, wild felids, gorillas, minks, ferrets, and white-tailed deer.^{3,14,22,28,50,54,55,72} (One source, Chandler JC and colleagues has not been peer reviewed). Several studies have been conducted to establish animal models for SARS-CoV-2 infection, including hACE2 mice, hamsters, NHP, cats, and ferrets.In this review, we discuss the natural occurrence of SARS-CoV-2 in animals and available animal models of SARS-CoV-2 infection and pathogenesis.     

Mitochondrial gene segregation in mammals: is the bottleneck always narrow?

Summary The segregation of a heteroplasmic silent polymorphism in the mitochondrial ND6 gene has been followed in a human maternal lineage comprising eight individuals and spanning three generations. Heteroplasmy persisted in all eight maternally related family members. More importantly, the frequencies of the two alleles showed relatively little variation among individuals or between generations. In contrast to the findings in other mammalian lineages, the present results indicate relatively slow mitochondrial gene segregation. A narrow bottleneck in the number of mitochondrial DNA (mtDNA) molecules, which occurs at some stage of oogenesis, has been advanced to explain rapid mammalian mitochondrial gene segregation. It is suggested here that the segregation of mitochondrial genes may be more complex than initially envisaged, and that models need to be developed that account for both rapid and slow segregation. One possibility, which reconciles both physical and genetic studies of mammalian mtDNA, is that the unit of mitochondrial segregation is the organelle itself, each containing multiple mtDNA molecules.     

Dominance relations in pairs of domestic cats

The dominance relationships in a group of adult male cats were studied by means of paired encounters in an observation arena which was equally familiar to both animals.In order to develop a good operational technique a pilot study was undertaken. Dominance relationships were determined by using criteria based upon approach/withdrawal or threatening postures similar to those described by Leyhausen (1973).During the encounters two conflicting tendencies seemed to appear: efforts to avoid confrontation and agonistic interactions. The intensity of the reaction varied from pair to pair.Some kinds of behaviour, not considered to be agonistic (such as exploration and, to a lesser extent, rubbing and urine marking), were performed more frequently by the dominant male.Furthermore it was shown that in the course of the experiments, the number of encounters in which no dominance could be assessed increased, probably due to increasing familiarity.The results of a pilot study on the effect of castration and testosterone treatment upon dominance relationships are also presented.     

Evidence of population bottleneck in Astragalus michauxii (Fabaceae), a narrow endemic of the southeastern United States

Genetic factors such as decreased genetic diversity and increased homozygosity can have detrimental effects on rare species, and may ultimately limit potential adaptation and exacerbate population declines. The Gulf and Atlantic Coastal Plain physiographic region has the second highest level of endemism in the continental USA, but habitat fragmentation and land use changes have resulted in catastrophic population declines for many species. Astragalus michauxii (Fabaceae) is an herbaceous plant endemic to the region that is considered vulnerable to extinction, with populations generally consisting of fewer than 20 individuals. We developed eight polymorphic microsatellites and genotyped 355 individuals from 24 populations. We characterized the population genetic diversity and structure, tested for evidence of past bottlenecks, and identified evidence of contemporary gene flow between populations. The mean ratios of the number of alleles to the allelic range (M ratio) across loci for A. michauxii populations were well below the threshold of 0.68 identified as indicative of a past genetic bottleneck. Genetic diversity estimates were similar across regions and populations, and comparable to other long-lived perennial species. Within-population genetic variation accounted for 92 % of the total genetic variation found in the species. Finally, there is evidence for contemporary gene flow among the populations in North Carolina. Although genetic factors can threaten rare species, maintaining habitats through prescribed burning, in concert with other interventions such as population augmentation or (re)introduction, are likely most critical to the long term survival of A. michauxii.     

Expression and activity of a novel cathelicidin from domestic cats

Cathelicidins are small cationic antimicrobial peptides found in many species including primates, mammals, marsupials, birds and even more primitive vertebrates, such as the hagfish. Some animals encode multiple cathelicidins in their genome, whereas others have only one. This report identifies and characterizes feline cathelicidin (feCath) as the sole cathelicidin in domestic cats (Felis catus). Expression of feCath is predominantly found in the bone marrow, with lower levels of expression in the gastrointestinal tract and skin. By immunocytochemistry, feCath localizes to the cytoplasm of neutrophils in feline peripheral blood. Structurally, the mature feCath sequence is most similar to a subgroup of cathelicidins that form linear α-helices. feCath possesses antimicrobial activity against E. coli D31, Salmonella enterica serovar Typhimurium (IR715), Listeria monocytogenes and Staphylococcus pseudintermedius (clinical isolate) similar to that of the human ortholog, LL-37. In contrast, feCath lacks the DNA binding activity seen with LL-37. Given its similarity in sequence, structure, tissue expression, and antimicrobial activity, the cathelicidin encoded by cats, feCath, belongs to the subgroup of linear cathelicidins found not only in humans, but also non-human primates, dogs, mice, and rats.     

Mutant allele frequencies in domestic cats of Taiwan

Preliminary data for Taiwanese cats generally agree with previous findings in far eastern populations, especially Vladivostok. However, surveys are still too few in number to achieve any detailed perspective for this vast region.     

Histopathology of feline panleukopenia in domestic cats.

Histopathological observations were carried out on 17 domestic cats naturally affected with feline panleukopenia. Principal lesions were found in the intestine, bone marrow, and lymphoid organs. Intestinal lesions were characterized by degenerative changes accompanied by the appearance of intranuclear inclusion bodies in the epithelial cells of the crypts. In contrast to the crypts, the villi were seldom involved. Hypoplasia, parenchymal degeneration, and activation of the reticuloendothelial system were observed in the bone marrow and lymphoid organs. Intranuclear inclusion bodies were found occasionally also in the reticular and parenchymal cells of the bone marrow, lymphoid organs, liver, adrenals, and pancreas. Most of the inclusion bodies were amphophilic when stained with hematoxylin and eosin and occupied the whole area of the nucleus without producing any zone of clear halo. While cells bearing inclusion bodies underwent degenerative changes constantly in the intestinal crypts, the formation of inclusion body was not accompanied by the degeneration of corresponding cells in any other organ. Pathological changes as mentioned above were considered to be closely related to the systemic infection of feline panleukopenia virus.     

Effect of GnRH analogs in postnatal domestic cats

The aim of this study was to reproductively assess the clinical and hormonal effects of a GnRH agonist (AG) and an antagonist (AN) administered during the postnatal period in domestic cats. Forty-eight male and female postnatal kittens were randomly assigned to deslorelin acetate 1.6 mg subcutaneous (AG; n = 16), acyline 33 μg/100 g subcutaneous weekly for 3 months (AN; n = 16), or control (CO; n = 16) which remained untreated. The cats were followed up (behavioral observation, physical examination, fecal sexual steroid determinations, mating test, and pregnancy diagnosis) up to puberty. Puberty was delayed (weeks) in the AG animals (62.9 ± 3.5; P < 0.01) but not in the AN (15.5 ± 1.7; P > 0.05) when they were compared with CO kittens (13.4 ± 0.4). Fifteen (15/16) of the AN and CO animals, and only 11 of 16 cats of the AG group were fertile (P > 0.1). No differences were found in body weight (P > 0.1) and measurements (P > 0.1), libido (P > 0.1) and in the appearance of side effects (P > 0.1; except a pyometra in an AG female) among groups. In both AG- and AN-treated males (testosterone; P < 0.01) and females (estradiol-17β; P < 0.01) fecal hormone concentrations were lower than in CO group during the first five postnatal weeks but not later. It is concluded that the neonatal administration of these AG and AN decreased fecal sexual steroids during the first postnatal weeks causing, the agonists but not the antagonist, a significant, reversible delay in puberty appearance.     

Transmission,infectivity, and neutralization of a spike L452R SARS-CoV-2 variant

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